Multiple osteochondromas

A Novel Pathogenic Large Duplication in EXT1 Identified in a Family with Multiple Osteochondromas

Multiple osteochondromas (MO) is an autosomal dominant disorder and the most common genetic skeletal dysplasia, characterized by the growth of bone outgrowths capped by cartilage, called osteochondromas. Most MO cases are caused by mutations in the exostosin-1 (EXT1) and exostosin-2 (EXT2) genes. Only 5% of MO-causative variants are represented by single or multiple exon deletions; to date, no pathogenic large duplication has been described in the literature. In the present study, we describe the novel in-tandem intragenic duplication c.(1128_1202)_(1284+29_1344)dup involving exon 4 of EXT1 (NM_000127.2), detected in a three-generation family with MO. The variant has been detected by MLPA (multiplex ligation-dependent probe amplification) and then confirmed with qPCR (quantitative PCR). Our finding expands the spectrum of MO-causing variants describing a pathogenic large duplication, underlying the importance of quantitative analysis in patients with negative sequencing.

Cases report: Mosaic structural variants of the EXT1 gene in previously genetically unconfirmed multiple osteochondromas

Multiple osteochondromas (MO) is a rare autosomal dominant skeletal disorder characterized by the development of multiple benign tumors known as osteochondromas. The condition is predominantly caused by loss-of-function variants in the EXT1 or EXT2 genes, facilitating relatively precise clinical diagnosis through established diagnostic criteria. Despite this, a notable percentage of MO cases (10%-20%) remains unresolved after sequencing coding regions and copy number analysis of both genes. In our study, we identified mosaic structural variants in two patients who initially yielded negative results on standard genetic analysis for MO. Specifically, mosaic deletions affecting exons 8-11 and exons 2-11 in the EXT1 gene were detected. RNA analysis was performed in one case, while both cases underwent genome sequencing. To date, only six mosaic copy number variations have been reported in association with MO, representing a minority among known variants in both genes. Our report provides a detailed analysis of these findings, highlighting the significance of advanced genetic testing techniques in detecting mosaic variants in the EXT1/2 genes.

Uncommon Expression of Osteochondroma in the Wrist: A Case Report

Introduction

Osteochondroma (OC) is a common benign bone tumor that usually arises from the metaphyseal region of long bones. Rarely, it can present in atypical locations such as the wrist and posing diagnostic challenges.

Case Report

We present a 42-year-old female with an incidental finding of OC on the volar aspect of the right wrist. The patient was referred for a musculoskeletal assessment due to a painful swelling, which was slowly increasing in size over 2 years, following mild trauma. With a suspicion of ganglion, investigations including X-ray and ultrasound led to surgical excision and histological examination, which confirmed a diagnosis of a benign OC.

Conclusion

The case emphasizes the importance of considering OC in the differential diagnosis of wrist swellings and highlights the effectiveness of surgical intervention in resolving symptoms.

Fluoride exposure and prevalence of osteochondroma in drinking water Endemic fluorosis areas of Heilongjiang Province, China: a cross-sectional study

To investigate the relationship between fluoride exposure and Osteochondroma (OC) prevalence, a cross-sectional study was conducted in drinking water endemic fluorosis areas of Heilongjiang Province, China. Our study first reported that the prevalence of OC was 2.3% in drinking water endemic fluorosis areas of Heilongjiang Province, China, and no difference in gender. Logistic regression analysis found that compared to 1st quartile participants, the prevalence of OC was 73% lower in the 2nd quartile participants of WF (Water fluoride), and 3.4 times higher among the 2nd quartile UF (Urinary fluoride) participants. Our study suggests that 0.259-0.420 mg/L of WF may be considered an appropriate level for reducing OC prevalence, while UF (≥0.750 mg/L) could slightly increase the prevalence of OC. In summary, the link between fluoride and OC prevalence is complicated and needs to be further investigated in a cohort population.

Paediatric Calcaneal Osteochondroma: A Case Report and a Literature Review

BACKGROUND

Heel pain in children is a common condition. The aetiology can be ascribed to fractures, osteochondrosis, tendinitis, calcaneal-navicular or talo-calcaneal coalition, osteomyelitis, rheumatic diseases, anatomic variants, malignant tumours (osteosarcoma, Ewing's sarcoma), and benign lesions (bone cyst, aneurismal bone cyst, osteoid osteoma, or exostosis). In particular, this manuscript focuses on a case of calcaneal exostosis in the paediatric age, aiming to highlight its rarity. Osteochondromas are benign tumours of the surface of the bone and the overlying cartilage. They grow until skeletal maturity and can cause stiffness, pain, cosmetic alterations, tendinitis, and neuro-vascular compression. The calcaneus is an extremely rare site for these tumours. Only two case reports of paediatric exostosis of the calcaneus bone are available.

METHODS

We describe a case of a girl of 16 years of age, affected by multiple cartilaginous exostosis, who presented with a painful mass on the inferior margin of the foot in the calcaneal region, which was diagnosed as an exostosis. The neoformation was excised, and the girl underwent clinical follow-up.

RESULTS

The patient was promptly discharged in good condition, and on the 25th postoperative day, she was completely pain-free and allowed weight bearing.

CONCLUSIONS

In the case of heel pain resistant to conservative treatment, the presence of an osteochondroma should be considered after excluding more common causes. If symptomatic, calcaneal osteochondromas could require surgical excision.

Peroneal Nerve Decompression in Patients with Multiple Hereditary Exostoses: Indications, Complications, and Recurrence

BACKGROUND

To our knowledge, there have been no studies examining peroneal nerve decompression and proximal fibular osteochondroma excision exclusively in patients with multiple hereditary exostoses (MHE). The purpose of this study was to evaluate the indications, complications, and recurrence associated with nerve decompression and proximal fibular osteochondroma excision in patients with MHE.

METHODS

The records on patients with MHE undergoing peroneal nerve decompression from 2009 to 2023 were retrospectively reviewed. Indications, clinical status, surgical technique, recurrence, and complications were recorded and were analyzed using the Fisher exact test, logistic regression, and the Kaplan-Meier method.

RESULTS

There were 126 limbs identified in patients with MHE who underwent peroneal nerve decompression. The most common indications were pain over the proximal fibula, tibialis anterior and/or extensor hallucis longus weakness, and dysesthesias and/or neuropathic pain. Seven cases experienced postoperative foot drop as a complication of the decompression and osteochondroma excision. Logistic regression found significant relationships between complications and excision of anterior osteochondromas (odds ratio [OR], 5.21; p = 0.0062), proximal fibular excision (OR, 14.73; p = 0.0051), and previous decompression (OR, 5.77; p = 0.0124). The recurrence rate was 13.8%, and all recurrences occurred in patients who were skeletally immature at the index procedure. The probability of skeletally immature patients not experiencing recurrence was 88% at 3 years postoperatively and 73% at 6 years postoperatively.

CONCLUSIONS

Indications for peroneal nerve decompression included neurologic symptoms and pain. The odds of a complication increased with excision of anterior osteochondromas and previous decompression. Recurrence of symptoms following decompression and osteochondroma excision was found exclusively in skeletally immature patients.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

The impact of inversions across 33,924 families with rare disease from a national genome sequencing project

Detection of structural variants (SVs) is currently biased toward those that alter copy number. The relative contribution of inversions toward genetic disease is unclear. In this study, we analyzed genome sequencing data for 33,924 families with rare disease from the 100,000 Genomes Project. From a database hosting >500 million SVs, we focused on 351 genes where haploinsufficiency is a confirmed disease mechanism and identified 47 ultra-rare rearrangements that included an inversion (24 bp to 36.4 Mb, 20/47 de novo). Validation utilized a number of orthogonal approaches, including retrospective exome analysis. RNA-seq data supported the respective diagnoses for six participants. Phenotypic blending was apparent in four probands. Diagnostic odysseys were a common theme (>50 years for one individual), and targeted analysis for the specific gene had already been performed for 30% of these individuals but with no findings. We provide formal confirmation of a European founder origin for an intragenic MSH2 inversion. For two individuals with complex SVs involving the MECP2 mutational hotspot, ambiguous SV structures were resolved using long-read sequencing, influencing clinical interpretation. A de novo inversion of HOXD11-13 was uncovered in a family with Kantaputra-type mesomelic dysplasia. Lastly, a complex translocation disrupting APC and involving nine rearranged segments confirmed a clinical diagnosis for three family members and resolved a conundrum for a sibling with a single polyp. Overall, inversions play a small but notable role in rare disease, likely explaining the etiology in around 1/750 families across heterogeneous clinical cohorts.

Pedunculated Osteochondroma Presenting as Verruca Vulgaris: A Diagnosis Requiring a High Index of Suspicion: Case Report

Introduction

Osteochondromas are the most common benign tumors of the bone and can be sessile or pedunculated. Although osteochondromas are typically seen in the long bones, they are rarely seen in the small bones of the hand or foot. Verruca vulgaris, also known as the common wart, is one of the most common skin conditions presenting to physicians and must be distinguished either clinically or histologically from other hyperkeratotic conditions, including bone conditions such as bone tumors that can place pressure on the skin and cause callus formation that can mimic a wart or create skin deformity. A high index of suspicion for underlying bone mass or tumor should be entertained when evaluating patients for skin conditions, particularly of the hand or foot, with failure to improve with treatment.

Case Report

This case report presents a 20-year-old male with a pedunculated osteochondroma of the left fourth distal phalanx with hyperkeratotic skin overlying the mass at the end of the toe. He was initially treated by a family doctor and podiatrist for verruca vulgaris for over 5 years with two treatments of liquid nitrogen cryotherapy and surgical excision of the mass when the treating podiatrist encountered bone and recommended radiographs. The family requested follow-up with our practice several days later after they were told the patient had a bone tumor. The patient requested surgical excision of the osteochondroma secondary to pain with activities and difficulties with his vocation as a pilot.

Conclusion

All physicians must be mindful of an underlying bone tumor or mass in patients presenting with skin changes, particularly about the foot or hand. Knowledge that an underlying bone tumor can present as a verruca vulgaris may prevent a delay in diagnosis or unnecessary treatment when evaluating and treating a patient with a skin lesion. Fortunately, our case was a benign osteochondroma; a malignant tumor with a delay in diagnosis could lead to loss of limb or life.

Pediatric diaphragmatic hernia induced by a rib osteochondroma

Diaphragmatic hernia in children is uncommon, especially when not congenital. We present a case of an 11-year old boy with a diaphragmatic hernia caused by a rib osteochondroma. The osteochondroma was surgically removed and the laceration in the diaphragm was repaired. This case shows the importance of being familiar with acquired diaphragmatic hernia in children, to recognize and prevent possible complications in an early stage.

Health-related quality of life and associated risk factors in patients with Multiple Osteochondromas: a cross-sectional study

PURPOSE

To evaluate the health-related quality of life and associated risk factors for Multiple Osteochondromas patients.

METHODS

A cross-sectional, observational study was conducted from May to December 2022 during the routine visit to the referral center for rare skeletal disorders. All patients with Multiple Osteochondromas aged ≥ 3 years were included. EuroQol 5-dimension questionnaires, and demographic, clinical, and surgical history data were collected. Descriptive statistics, Fisher's exact test, One-sample t-test, Spearman's correlation, and multiple linear and logistic regression were performed to analyze the data. Results are reported following STROBE guidelines.

RESULTS

A total of 128 patients were included in the study, with a mean age of 14 [SD, 10] years. The mean EQ-5D Index Value was 0.863 [SD, 0.200] and the EQ-VAS was 84 [SD, 19] with a positive correlation between two scores [r = 0.541, p < 0.001]. Patients frequently referred problems in pain/discomfort [78.8%], anxiety/depression [50%], and usual activities [38.8%] dimensions. Increasing age was the common risk factor for health-related quality of life [p < 0.000], as well as Index Value and VAS scores were significantly lower in surgical patients [p = 0.001 and p < 0.001, respectively].

CONCLUSION

Increasing age and surgical procedures were found highly associated with reduced health-related quality of life in Multiple Osteochondromas patients. Our findings provide relevant information to support the establishment of patient-centered healthcare pathways and pave the way for further research into medical and non-medical therapeutic strategies for these patients.

Multiple Hereditary Exostoses instigating a popliteal pseudoaneurysm in a young Middle Eastern male: A case report and literature review

INTRODUCTION AND IMPORTANCE

Multiple Hereditary Exostoses is a rare autosomal dominant bone disorder that predominantly affects males at an incidence of (1:50,000 to 1:100,000) in Western populations. The etiology is owed to mutations in the EXT gene group, specifically EXT1 and EXT2 which cause the formation of Osteochondromas. Diagnosis is typically established in childhood. Nevertheless, vascular complications are extremely rare while being potentially fatal. Therefore, timely diagnosis and treatment are vital for such patients.

CASE PRESENTATION

We present the case of a 37-year-old Middle Eastern male with Multiple Hereditary Exostoses who experienced sudden-onset left lower limb pain persisting for a month prior to admission. It was associated with coldness and paresthesia of the ipsilateral lower limb. The presurgical radiological workup uncovered a popliteal pseudoaneurysm subsequent to Multiple Hereditary Exostoses.

CLINICAL DISCUSSION

Through open surgery, the vascular perfusion was successfully restored, and a subsequent supra- to infra-geniculate popliteal artery anastomosis via saphenous vein grafting was done. Furthermore, the Osteochondroma was utterly resected to limit recurrence of another vascular injury. The following histopathological analysis confirmed the diagnosis of an Osteochondroma as a result of MHE.

CONCLUSION

Multiple Hereditary Exostoses is a rare occurrence leading to pseudoaneurysms. This event underscores the need for further documentation to aid in establishing a prompt diagnosis and carrying out suitable interventions. Considering this pathology in a multidisciplinary approach ensures proper treatment. Following a comprehensive literature review, our case stands as the first case in the published literature from our country which emphasizes its value and rarity.

Extensive Osteochondroma of the Talus Presenting As Syndesmotic Joint Extension and Posterior Inferior Tibiofibular Ligament Rupture: A Reportof a Rare Case and a Review of the Literature

This case report describes a rare occurrence of talar osteochondroma extending into syndesmosis, causing disruption of the interosseous membrane and the posterior inferior tibiofibular ligament (PITFL). This type of presentation for a talar osteochondroma is the first of its kind reported in the literature based on current knowledge. A detailed preoperative radiological assessment was crucial in planning the surgical approach and preparing for syndesmotic stabilization during the excision. The patient underwent successful and complete excision of the osteochondroma, and the syndesmosis was stabilized using a cortical screw along with anatomical repair of the PITFL. Apart from delayed wound healing, the patient exhibited good functional outcomes in terms of gait and ankle range of motion at the six-month follow-up. This case serves as a valuable reference for similar presentations in the future, emphasizing the importance of thorough preoperative assessment and appropriate treatment planning.

Secondary peripheral chondrosarcoma in multiple osteochondromas: a retrospective single-institution case series

BACKGROUND

Multiple osteochondromas is genetic disorder characterized by the formation of multiple benign cartilage-capped bone tumors, named osteochondromas, during skeletal development. The most feared complication is the secondary peripheral chondrosarcoma, a malignant cartilaginous neoplasm that arises from the chondroid cap of pre-existent osteochondromas. We conducted a retrospective cohort study on patients diagnosed and followed up from 1960 to 2019 to describe the clinical and pathological features of individuals affected by peripheral chondrosarcoma in multiple osteochondromas, to evaluate follow up information and individual outcome and to compare the results with literature. Data, including age, gender, site, histological grade, cartilage cap thickness, surgical treatments, surgical margins, genotype mutational status as well as treatment details were captured from the hospital electronic health records and from Registry of Multiple Osteochondromas. In addition, a complete histological review of all hematoxylin and eosin (H&E)-stained sections has been performed by expert pathologists.

RESULTS

One hundred five of the screened cases were included in the present study. The age at diagnosis of SPC ranges from 13 to 63, with median age at diagnosis of 34 years. The site most frequently affected by malignant degeneration was the pelvis (46 patients, 44%) with higher incidence in male patients (32 males vs.14 females). The second one was lower limbs (including femur, fibula, or tibia), identified in 35 patients. Histological information - available for 103 patients - showed: 59 patients with grade 1; 40 patients had a grade 2 and 4 patients had a grade 3. The most common surgical treatment was the complete resection, followed by debulking, amputation and partial resection. Most of cases did not have recurrence of the disease. Outcome in disease-free survival highlights that a worse course of the disease was associated with histological grade 2 or 3, and partial resection surgery. In most of analyzed cases (94%) a pathogenic variant was identified.

CONCLUSIONS

In conclusion, the present study gives an overview of the secondary peripheral chondrosarcomas, confirming that this disease represents an impacting complication for multiple osteochondromas patients and suggests that malignant transformation can occur also in younger patient, in a not irrelevant number of cases.

Medullary Compression by a Cervical Osteochondroma in a Patient with Multiple Hereditary Exostoses: A Case Report

CASE

A 19-year-old man with Multiple Hereditary Exostoses presented with cervical pain without neurological symptoms and/or signs. Magnetic resonance revealed a large C2 osteochondroma, occupying a part of the medullary canal. He was submitted to an en bloc resection with hemilaminectomy without fusion. At the 1-year follow-up, he presented resolution of pain and no neurological symptoms or signs, without cervical instability or radiological signs of disease recurrence.

CONCLUSION

Cervical osteochondroma is usually asymptomatic. Neurological compression and differentiation to chondrosarcoma are the main concerns. Surgical excision allows the local cure of the disease and is usually performed without fusion.

Is total-body MRI useful as a screening tool to rule out malignant progression in patients with multiple osteochondromas? Results in a single-center cohort of 319 adult patients

PURPOSE

To evaluate the results of total-body (TB) MRI used as a screening tool for assessment or exclusion of malignant transformation in patients with hereditary multiple osteochondromas (HMO).

PATIENTS AND METHODS

In a single-institute cohort of MO patients, 366 TB-MRI examinations, including T1-weighted and STIR images, were performed for screening and follow-up purposes to rule out the malignant transformation, and retrospectively analyzed. In each patient, the presence and location of osteochondromas in the axial and appendicular bones were recorded. Forty-seven patients underwent a second TB surveillance in this period. STIR sequences were used to identify sites of increased signal intensity that could represent suspicious thickened cartilage caps or indeterminate reactive changes related to osteochondromas.

RESULTS

In 82% of patients, one or more OC locations were determined in one or more flat bones. In 366 exams, nine OC (2,5 %) with suspicious imaging features were identified. These proved to be peripheral chondrosarcomas after targeted MRI and resection were performed. All nine malignant lesions were in flat bones (pelvis 5, ribs 3, scapula 1). Three of these patients were 19 years of age. In 12 patients who had peripheral or intraosseous low-grade chondrosarcoma in their history, before their first TB-MRI, no new lesions were identified. Twenty-three additional TB-MRI exams, demonstrating focal high T2 signal intensity, also gave rise to performing additional targeted MRI. One OC of the distal femur was excised and appeared benign. No suspicious cartilage caps were depicted on the remaining 22 targeted MRI exams but instead increased T2 signal was clarified by reactive changes (frictional bursitis, soft tissue edema) in close relation with benign osteochondromas. No malignant lesions were found in 47 patients who had a second TB surveillance (mean interval between exams 3.2 years, range 2-5 years).

CONCLUSION

TB-MRI can identify malignant transformation of osteochondromas in HMO patients. All peripheral chondrosarcomas occurred in flat bones (ribs, scapula, pelvis) in our study. TB-MRI might assist in triage between higher risk patients with a high burden of OC, including the location of OC in main flat bones vs lower risk patients without OC of the flat bones.

Chondrosarcoma secondary to hereditary multiple osteochondromas with spinal cord compression: A case report and systematic review

Background

Hereditary multiple osteochondromas (HMOs) are a rare genetic disorder characterized by the formation of multiple benign osteochondromas that can undergo malignant transformation into chondrosarcoma.

Case Description

A 24-year-old male with a history of HMO and osteochondroma surgery 4 years ago, presented with back pain and paresthesias. The magnetic resonance showed a right paravertebral infiltrating mass at the T12-L1 level causing spinal cord compression. Following en bloc resection of the tumor, the patient's symptoms/ signs resolved. The final pathological diagnosis was consistent with a chondrosarcoma.

Conclusion

Chondrosarcomas secondary to HMO with spinal cord compression are rare. These patients often presenting with significant myelopathy/cord compression should undergo gross total resection where feasible to achieve the best outcomes.

Limb Salvage Surgery in an Enormously Large Pelvic Malignant Bone Tumor

Introduction

Malignant transformation of pelvic osteochondroma is a rare entity. Large size and late presentation impose threat to life as well as limb. We report a case of limb salvage surgery in an enormously large secondary chondrosarcoma arising from pelvic bone.

Case Report

A 60-year-old male presented with a colossal swelling at groin reaching up to distal thigh. He was walking with a wide-based gait due to pain and discomfort. 30 year back, the patient first reported this swelling of pea size, for which he was advised surgery but due to fear of surgery and economic reason he refused. Swelling gradually increased in size and reached up to distal thigh in the past 30 years. It was hard and non-tender up to 6 months back, when suddenly a change in consistency from hard to soft in distal area was noticed. On examination, a large soft cystic swelling was hanging from his pubic area. Tumor was fixed at base on proximal end. On magnetic resonance imaging, size of tumor was 281 mm in length, 263 mm in width, and 250 mm in anteroposterior diameter. Tumor was arising from superior and ischiopubic rami. However, no intra-articular extension was seen. A radiographic skeletal survey and bone scan did not reveal any other lesion. On biopsy, chondrogenic tumor composed of lobules of chondroid material with no cellular atypia or evidence of malignancy was reported. Considering the age of patient, rapid progression in recent months, size and duration of tumor, and type 3 pelvic resection was planned. Using utilitarian pelvic incision with perineal extension, separating long adductor muscles and deep femoral artery tumor, tumor excised with osteotomy at pubic symphysis, and on superior and inferior pubic rami. With minor wound complications, wound healed in 3 weeks. Post-operative biopsy reported as Grade 1 chondrosarcoma. At 3-year follow-up, the patient has no complains and no sign of recurrence noticed.

Conclusion

Limb salvage surgery is a suitable option even in enormously large musculoskeletal malignancy. Proper counseling and tracking of patients are must to avoid future complications.

Modified gradual ulnar lengthening for treatment of Masada type IIb forearm deformity in children with hereditary multiple osteochondromas

Objective

To investigate the effect of modified gradual ulnar lengthening in the treatment of Masada type IIb forearm deformity in children with hereditary multiple osteochondromas (HMO).

Patients and methods

From May 2015 to October 2020, 12 children with Masada type IIb forearm deformity caused by HMO underwent modified gradual ulnar lengthening in our hospital. Clinical and imaging data were retrospectively analyzed. Clinical evaluation included wrist flexion and extension, wrist ulnar and radial deviation, forearm pronation and supination, and elbow range of motion. The radiographic parameters measured included the radial articular angle, carpal slip, and relative ulnar shortening.

Results

The mean operative age of the 12 patients (9 male, 3 female) was 8.5 ± 2.7 years, the mean follow-up was 31.5 ± 5.7 months, and the mean ulnar lengthening was 43.3 ± 9.9 mm. There was no significant difference in the radial articular angle between the preoperative period and the last follow-up (from 36.5° ± 9.2° to 33.8° ± 5.1°, p > 0.05). However, significant changes were found in carpal slip (from 61.3% ± 18.8% to 33.8% ± 20.8%) and relative ulnar shortening (from 5.8 ± 3.5 mm to -0.9 ± 4.85 mm) (p < 0.05). The range of motion significantly improved after modified gradual ulnar lengthening, including wrist flexion (from 38.3° ± 6.2° to 55.8° ± 9.0°), wrist extension (from 45.0° ± 9.8° to 61.7° ± 8.1°), wrist ulnar deviation (from 41.3° ± 8.6° to 29.6° ± 7.8°), wrist radial deviation (from 18.3° ± 6.2° to 30.0° ± 5.6°), forearm pronation (from 44.6° ± 7.2° to 62.1° ± 8.6°), forearm supination (from 50.0° ± 7.1° to 52.9° ± 6.6°), and elbow range of motion (from 117.1° ± 10.1° to 127.9° ± 5.4°) (all p < 0.05). During follow-up, there was one case of needle tract infection and one case of bone nonunion.

Conclusion

Modified gradual ulnar lengthening can effectively treat Masada type IIb forearm deformity caused by HMO and improve forearm function.

Sacroiliac joint involvement in osteochondromatosis: identifying its prevalence and characteristics from cross-sectional imaging

PURPOSE

Apart from a few case reports, sacroiliac joint (SIJ) involvement in osteochondromatosis has not been studied. We aimed to determine the prevalence and characteristics of such involvement using cross-sectional imaging.

METHODS

In this retrospective study, three observers (one junior radiologist and two musculoskeletal radiologists) independently reviewed computed tomography (CT) or magnetic resonance imaging (MRI) of patients in our database who had osteochondromatosis (≥2 osteochondromas across the skeleton) for SIJ involvement. The final decision was reached by the consensus of the two musculoskeletal radiologists in a later joint session.

RESULTS

Of the 36 patients with osteochondromatosis in our database, 22 (61%) had cross-sectional imaging covering SIJs (14 females, 8 males; age range 7-66 years; mean age 23 years; 13 MRI, 9 CT). Of these, 16 (73%) had intra-articular osteochondromas. For identifying SIJ osteochondromas on cross-sectional imaging, interobserver agreement was substantial [κ = 0.67; 95% confidence interval (CI): 0.34, 1.00] between the musculoskeletal radiologists and moderate (κ = 0.59; 95% CI: 0.23, 0.94) between the junior radiologist and the final consensus decision of the two musculoskeletal radiologists. In the cohort with cross-sectional imaging, the anatomical variations of the accessory SIJ (n = 6, 27%) and iliosacral complex (n = 2, 9%) were identified in six different patients with (n = 2) and without (n = 4) sacroiliac osteochondromas.

CONCLUSION

Cross-sectional imaging shows frequent (73%) SIJ involvement in osteochondromatosis, which, although a rare disorder, nevertheless needs to be considered in the differential diagnosis of such SIJ anatomical variants as the accessory SIJ and iliosacral complex. Differentiating these variants from osteochondromas is challenging in patients with osteochondromatosis.

Concurrent intraosseous cartilaginous lesions in patients with multiple osteochondromas identified on total-body MR imaging

PURPOSE

To assess the prevalence of intraosseous cartilaginous lesions in patients with multiple osteochondromas based on total-body (TB) MRI examinations, used for screening purposes.

SUBJECTS AND METHODS

Between 2013 and 2020, TB-MRI examinations were performed in 366 patients with proven multiple osteochondromas syndrome, to rule out malignant progression. For this study, presence, or absence of intraosseous central or eccentrical chondroid lesions, defined as lobulated lesions with low signal intensity on T1-weighted images, replacing bone marrow and high signal intensity equal to fluid on T2-weighted images in the bone marrow of the meta-diaphysis of (one of) the long bones, were recorded in the long bones as part of a TB-MRI protocol.

RESULTS

In 62 patients out of the 366 MO patients (17%), one or more intraosseous chondroid lesions (either enchondroma or atypical cartilaginous tumor) were detected. The age of the patients at time of diagnosis ranged from 17 to 61 years (mean, 36). Size of the lesions varied from 4 to 69 mm (mean, 16.3 mm). The most common location was the proximal femur (n = 29), followed by the distal femur and proximal humerus (n = 18 and n = 10, respectively). In nine of the patients with an intraosseous chondroid lesion, a second and/or third TB-MRI were available during the period of evaluation (mean interval, 2.7 years between the exams). In none of these patients increase of these intraosseous lesions was noticed.

CONCLUSION

Intraosseous chondroid lesions (enchondroma and ACT) appear to occur more frequently in MO patients than in the general population. TB-MRI allows to detect these, besides the identification of OC with suspicious features.

Thin Cartilage Cap May Be Related to the Spontaneous Regression in Pediatric Patients with Osteochondroma

BACKGROUND

The spontaneous regression of osteochondromas is rare, and only a few cases have been reported. Furthermore, the precise mechanism underlying spontaneous regression is unknown. This study aimed to examine the radiological findings of osteochondromas that had spontaneous regression and to identify potential indicators of this uncommon phenomenon in skeletally immature patients with osteochondromas.

METHODS

We included 28 patients (15 males and 13 females) who met the eligibility criteria between 2002 and 2019. The mean age at initial diagnosis was 9.7 years old (2-16 years). The mean follow-up period was 6.4 years (3-16 years).

RESULTS

Of the 28 patients, 10 (35.7%) had osteochondroma resolution. The osteochondroma resolved in one patient and regressed in nine. Tumor shrinkage is related to the thickness of the cartilage cap. The thickness of the cartilage cap did not correlate with age.

CONCLUSIONS

Tumor shrinkage is associated with a thinner cartilage cap on magnetic resonance imaging. The thickness of the cartilage cap may be an important predictor of spontaneous regression in pediatric patients with osteochondroma.

Osteochondroma of the Scapula: A Case Report and Literature Review

Osteochondromas are bone lesions composed of medullary and cartilaginous bone covered by a cap of hyaline cartilage. The presence of medullary and cortical bone with the continuity of the tumor is pathognomonic for osteochondroma and aid in establishing the diagnosis. We report a case of a two-year-old girl who presented to our clinic following her mother noticing a palpable, growing, and painful mass on her left scapula. There was no limitation in the range of motion. A clear-cut mass was seen on the dorsal aspect and palpated measuring around 2.5x3 cm. Surgical excision of the mass followed by histologic examination confirmed osteochondroma. Upon follow-up, the patient had no pain and had a full range of left shoulder motion without discomfort or pain. In conclusion, scapular exostoses are very rare and more so when they present dorsally. Symptomatic lesions can be managed effectively with surgical excision of exostosis.

Genetic analysis of seven pateints with Hereditary Multiple Osteochondromas (HMO)

BACKGROUND

HMO (Hereditary Multiple Osteochondroma), an uncommon autosomal dominant disorder, is characterized by the development of multiple osteochondromas, which are nonmalignant cartilage-capped bone tumors growing outwards from long bone metaphyses.

METHODS

The present work retrospectively analyzed seven children with HMO who were enrolled for routine clinical diagnosis and treatment, including X-ray examination. Subsequent genetic detection was carried out using whole exome sequencing (WES). In addition, this work applied Sanger sequencing to be the validation approach. Moreover, this work also examined amino acid (AA) evolutionary conservatism under the influence of certain missense variants.

RESULTS

The clinical indications of all seven patients and their family members were thoroughly indexed. WES identified diagnostic variants in the EXT1 or EXT2 gene in these patients. In these variants, four were reported for the first time, namely EXT1: c.1285-2A>T, EXT2: c.1139delT, EXT1: c.203G>A, and EXT1: c.1645_1673del. Familial validation revealed that three of the variants were hereditary, while the other four were de novo, which was consistent with the phenotype in each case.

CONCLUSION

Our results expanded HMO variation spectrum, and laid certain foundations for the precise counseling of those affected families.

Hemothorax caused by costal exostosis injuring diaphragm: a case report and literature review

Background

Osteochondromas, also known as exostoses, are the most common benign tumors of bone and can be classified into isolated and multiple osteochondromas. A great majority of osteochondromas is asymptomatic, painless, slow-growing mass, and incidentally found. However, osteochondromas occurring in adolescence or in adult patients can grow in size and become symptomatic as a result of mechanical irritation of the surrounding soft tissues or peripheral nerves, spinal cord compression, or vascular injury.

Case presentation

We present a case of a 13-year-old girl with spontaneous hemothorax, the cause of which was identified by limited thoracotomy with the aid of video-assisted thoracic surgery to be bleeding from a diaphragmatic laceration incurred by a costal exostosis on the left sixth rib. Preoperative chest computed tomography (CT) depicted a bony projection arising from the rib and bloody effusion in the intrathoracic cavity, but was unable to discern the bleeding cause from the lung or the diaphragm. This case will highlight our awareness that costal exostosis possibly results in bloody pleural effusion. Meanwhile, English literatures about solitary costal exostosis associated with hemothorax were searched in PubMed and nineteen case reports were obtained. Combined our present case with available literature, a comprehensive understanding of this rare disease entity will further be strengthened.

Conclusions

Injury to the diaphragm is the primary cause of hemothorax caused by costal osteochondroma, including the present case. Thoracic CT scan can help establish a diagnosis of preoperative diagnosis of costal osteochondroma. Surgical intervention should be considered for those patients with symptomatic osteochondroma of the rib. Combined with our case and literature, prophylactic surgical removal of intrathoracic exostosis should be advocated even in asymptomatic patients with the presentation of an inward bony spiculation.

Update on the imaging features of the enchondromatosis syndromes

Ollier disease and Maffucci syndrome are the commonest enchondromatosis subtypes, arising from non-hereditary mutations in the IDH1 and IDH2 genes, presenting in childhood and being characterised by multiple enchondromas. Maffucci syndrome also includes multiple soft tissue haemangiomas. Aside from developing bony masses, osseous deformity and pathological fracture, ~ 40% of these patients develop secondary central chondrosarcoma, and there is increased risk of non-skeletal malignancies such as gliomas and mesenchymal ovarian tumours. In this review, we outline the molecular genetics, pathology and multimodality imaging features of solitary enchondroma, Ollier disease and Maffucci syndrome, along with their associated skeletal complications, in particular secondary chondrosarcoma. Given the lifelong risk of malignancy, imaging follow-up will also be explored. Metachondromatosis, a rare enchondromatosis subtype characterised by enchondromas and exostoses, will also be briefly outlined.

Mutations in the heparan sulfate backbone elongating enzymes EXT1 and EXT2 have no major effect on endothelial glycocalyx and the glomerular filtration barrier

In this study, the effect of heterozygous germline mutations in the heparan sulfate (HS) glycosaminoglycan chain co-polymerases EXT1 and EXT2 on glomerular barrier function and the endothelial glycocalyx in humans is investigated. Heparan sulfate (HS) glycosaminoglycans are deemed essential to the glomerular filtration barrier, including the glomerular endothelial glycocalyx. Animal studies have shown that loss of HS results in a thinner glycocalyx. Also, decreased glomerular HS expression is observed in various proteinuric renal diseases in humans. A case report of a patient with an EXT1 mutation indicated that this could result in a specific renal phenotype. This patient suffered from multiple osteochondromas, an autosomal dominant disease caused by mono-allelic germline mutations in the EXT1 or EXT2 gene. These studies imply that HS is indeed essential to the glomerular filtration barrier. However, loss of HS did not lead to proteinuria in various animal models. We demonstrate that multiple osteochondroma patients do not have more microalbuminuria or altered glycocalyx properties compared to age-matched controls (n = 19). A search for all Dutch patients registered with both osteochondroma and kidney biopsy (n = 39) showed that an EXT1 or EXT2 mutation does not necessarily lead to specific glomerular morphological phenotypic changes. In conclusion, this study shows that a heterozygous mutation in the HS backbone elongating enzymes EXT1 and EXT2 in humans does not result in (micro)albuminuria, a specific renal phenotype or changes to the endothelial glycocalyx, adding to the growing knowledge on the role of EXT1 and EXT2 genes in pathophysiology.

Persistent Atraumatic Knee Pain in a Teenage Female with Bony Protuberance Secondary to Hook-Shaped Osteochrondroma

A 13-year-old female presented at her pediatrician's office with a complaint of sharp, intermittent, right-sided knee pain that had been present for the previous three days without any known trauma and no association with activity. Her medical history was significant for fractures, and on physical exam, there was a hard mass palpated on the medial aspect of her distal thigh that was nontender, nonmobile, and without overlying skin changes. The plain radiograph findings were consistent with a hook-shaped osteochondroma of the right medial distal metaphysis. Orthopedics recommended conservative management with continued ibuprofen for pain and six-week follow-up with repeat radiograph to evaluate for progression. The follow-up radiograph showed no interval growth. However, due to continued pain, the patient had surgical excision of the osteochondroma six months after initial presentation, allowing her to finish her current soccer season. The surgery was successful, and the patient did well after operation with no residual pain.

Hereditary Multiple Exostoses-A Review of the Molecular Background, Diagnostics, and Potential Therapeutic Strategies

Hereditary multiple exostoses (HMEs) syndrome, also known as multiple osteochondromas, represents a rare and severe human skeletal disorder. The disease is characterized by multiple benign cartilage-capped bony outgrowths, termed exostoses or osteochondromas, that locate most commonly in the juxta-epiphyseal portions of long bones. Affected individuals usually complain of persistent pain caused by the pressure on neighboring tissues, disturbance of blood circulation, or rarely by spinal cord compression. However, the most severe complication of this condition is malignant transformation into chondrosarcoma, occurring in up to 3.9% of HMEs patients. The disease results mainly from heterozygous loss-of-function alterations in the EXT1 or EXT2 genes, encoding Golgi-associated glycosyltransferases, responsible for heparan sulfate biosynthesis. Some of the patients with HMEs do not carry pathogenic variants in those genes, hence the presence of somatic mutations, deep intronic variants, or another genes/loci is suggested. This review presents the systematic analysis of current cellular and molecular concepts of HMEs along with clinical characteristics, clinical and molecular diagnostic methods, differential diagnosis, and potential treatment options.

Unusual location of osteochondroma in the temporal region in a patient with functional pituitary adenoma

Osteochondromas are common in the long bones and relatively rare in the head and neck regions. We herein report a case of a solitary temporal bone osteochondroma associated with a functional pituitary adenoma hypersecreting prolactin. The patient was a 48-year-old man with progressive, painless temporal swelling associated with gradual visual loss, gynaecomastia, erectile dysfunction, and loss of libido. A brain computed tomography scan with bone windows showed right temporal sessile bony expansion and a pituitary tumour. A pituitary function test revealed hyperprolactinaemia. His symptoms resolved with medical management, and excisional biopsy of the temporal tumour confirmed an osteochondroma. To the best of our knowledge, this is the first reported case of a solitary temporal bone osteochondroma with a functional pituitary adenoma hypersecreting prolactin.

A Solitary Ventral Scapular Osteochondroma causing Pseudo-winging of Scapula: A Case Report

Introduction:

Winging of scapula is defined as a failure of dynamic stabilizing structures that anchor the scapula to the chest wall, leading to prominence of the medial border of scapula. It could be primary, secondary, or voluntary. Primary winging could be true winging due to neuromuscular causes or pseudo-winging due to osseous or soft-tissue masses. A scapular osteochondroma is a very rare presentation site and causes pseudo-winging leading to pushing away of the scapula away from the chest wall presenting as medial border prominence. Here, we are reporting a rare case of a scapular osteochondroma causing a pseudo-winging of the scapula.

Case Report:

A 2-year-old male child presented with painless, immobile, and non-fluctuant swelling over the left scapular region, insidious in onset and progressive in nature. On examination, a non-tender, immobile swelling was palpable with a painless and unrestricted range of motion at the shoulder joint. After evaluating radiographs and CT scan, the patient was diagnosed to have a ventral scapular osteochondroma leading to pseudo-winging of the scapula.

Conclusion:

Despite the rarity, a differential diagnosis of a scapular osteochondroma should be kept in mind while examining a young child presenting with a winged scapula.

Spontaneous pneumothorax in a 17-year-old male patient with multiple exostoses: A case report and review of the literature

BACKGROUND

Multiple exostoses generally develop in the first decade of life. They most frequently arise from the distal femur, proximal tibia, fibula, and proximal humerus. Costal exostoses are rare, contributing to 1%–2% of all exostoses in hereditary multiple exostoses (HME). They are usually asymptomatic, but a few cases have resulted in severe thoracic injuries. Pneumothorax caused by costal exostoses is rare, with only 13 previously reported cases. We report a new case of pneumothorax caused by costal exostoses.

CASE SUMMARY

A 17-year-old male with HME underwent surgery for removal of exostoses around his right knee. Four months following the operation, he felt chest pain when he was playing the trumpet; however, he did not stop playing for a week. He was referred to our hospital with a chief complaint of chest pain. The computed tomography (CT) scan revealed right pneumothorax and multiple exostoses in his right ribs. The CT scan also revealed visceral pleura thickness and damaged lung tissues facing the exostosis of the seventh rib. We diagnosed that exostosis of the seventh rib induced pneumothorax. Costal exostosis resection was performed by video-assisted thoracoscopic surgery (VATS) 2 wk after the onset. The patient’s postoperative course was uneventful, and there was no recurrence of pneumothorax for 2 years.

CONCLUSION

Costal exostoses causing thoracic injuries should be resected regardless of age. VATS must be considered in cases with apparently benign and relatively small exostoses or HME.

Benign Cartilage-forming Tumors

Although uncommon in many pathology practices, cartilage-forming tumors represent some of the most frequent primary bone tumors. Diagnosis can be challenging given their variable histologic spectrum and the presence of overlapping morphologic, immunohistochemical, and genetic features between benign and malignant entities, particularly low-grade malignancies. Correlation with clinical findings and radiographic features is crucial for achieving an accurate diagnosis and appropriate clinical management, ranging from observation to excision. Tumors can be characterized broadly by their location in relation to the bone (surface or intramedullary). In specific instances, ancillary testing may help.

Multiple Osteochondromas Comorbid With Enlarged Parietal Foramina, Elongated Styloid Processes, and Tibiofibular Synostosis

OBJECTIVES

This study investigates a unique case of multiple osteochondromas (MO) comorbid with enlarged parietal foramina and correlates the findings with the existing literature. The aim of this study is to provide a deeper understanding of anatomic variation for physicians.

METHODS

A 66-year-old White male donor was examined during a routine cadaveric dissection performed by medical students in an anatomy laboratory. Detailed exploration of the skeleton and organs was performed, and photographs were taken. Tissue samples were obtained from multiple outgrowths, and histopathologic examination was done.

RESULTS

Bilateral bony growths were noted rising from the long bones of the upper and lower extremities (femur, tibia, fibula, and radius). An accessory muscle was found to be associated with the left radial bony growth. Histopathologic examination was positive for osteochondroma. Inspection of the skull revealed enlarged parietal foramina. Other findings included tibiofibular synostosis, abnormally shaped vertebral bodies and ribs, and elongated styloid processes of the skull.

CONCLUSIONS

In combination with the histopathologic examination, the case report and literature review elucidate a more precise clinical picture for those affected with MO or similar disorders. This report also emphasizes the necessity of further investigation of the pathogenesis of MO and Potocki-Shaffer syndrome.

The Rizzoli Multiple Osteochondromas Classification revised: describing the phenotype to improve clinical practice

Multiple osteochondromas (MO) is a rare disorder, characterized by benign osteocartilaginous tumors (osteochondromas), arising from the perichondrium of bones. The osteochondromas increase during growth, frequently causing deformities and limitations. Our study aims to analyze the data captured by the Registry of Multiple Osteochondromas, to refine Istituto Ortopedico Rizzoli (IOR) Classification, providing a representative picture of the phenotypic manifestations throughout the lifespan. We conducted a single‐institution cross‐sectional study. Patients were categorized according to IOR Classification, which identifies three patients' classes on the presence/absence of deformities and/or limitations. The present dataset was compared with our previously published data, to refine the classification. Nine hundred sixty‐eight patients were included: 243 children (<10 years), 136 adolescents (10–15 years), and 589 adults. Of the entire population, half patients presented at least one deformity, and one quarter reported at least one limitation. Compared with our previous study, the amount of children was more than doubled and the percentage of mild/moderate cases was notably increased, giving a better disease overview throughout the lifespan and suggesting a different cut‐off for dividing Class II in subclasses. We confirmed that MO is characterized by phenotypic heterogeneity, suggesting that an early classification of the disease may offer a useful tool to follow disease pattern and evolution, to support clinical practice, and to propose timely interventions.

Identification of a novel EXT2 frameshift mutation in a family with hereditary multiple exostoses by whole-exome sequencing

BACKGROUND

Hereditary multiple exostoses (HME), also referred to as multiple osteochondromas, is an autosomal dominant skeletal disease characterized by the development of multiple overgrown benign bony tumors capped by cartilage and is associated with bone deformity, joint limitation, and short stature. Mutations in exostosin glycosyltransferase (EXT)1 and EXT2 genes, which are located on chromosomes 8q24.1 and 11p13, contribute to the pathogenesis of HME.

METHODS

In the present study, a genetic analysis of a four-generation Chinese family with HME was conducted using whole-exome sequencing (WES), followed by validation using Sanger sequencing.

RESULTS

A novel heterozygous frameshift mutation in exon 5 of EXT2 (c.944dupT, p.Leu316fs) was identified in all affected individuals but was not detected in any unaffected individuals. This mutation results in a frameshift that introduces a premature termination codon at position 318 (p.Leu316fs) with the ability to produce a truncated EXT2 protein that lacks the last 433 amino acids at its C-terminal to indicate a defective exostosin domain and the absence of the glycosyltransferase family 64 domain, or to lead to the degradation of mRNAs by nonsense-mediated mRNA decay, which is critical for the function of EXT2.

CONCLUSION

Our results indicate that WES is effective in extending the EXT mutational spectra and is advantageous for genetic counseling and the subsequent prenatal diagnosis.

Osteochondromas: An Updated Review of Epidemiology, Pathogenesis, Clinical Presentation, Radiological Features and Treatment Options

Osteochondroma, the most common benign bone tumor, is a projection on the external surface of the bone, which can be sessile or pedunculated. 85% of osteochondromas present as solitary lesions, while 15% occur in the context of hereditary multiple exostoses (HME), a genetic disorder that is inherited in an autosomal dominant manner. Although often asymptomatic, symptoms may eventuate from compression of adjacent vessels or nerves, fractures, osseous deformities, bursa formation, or malignant transformation. Cartilage cap thickness >2 cm in adults or >3 cm in children as well as new onset of pain or growth, or rapid growth of the lesion, especially after the closure of the growth plate, might reflect cancerous transformation. Surgical resection is indicated for symptomatic lesions, complications, cosmetic reasons or malignant transformation. Excision of the tumor with free margin is the treatment of choice. Local recurrence is less than 2% if complete resection is achieved.

Non-subungual presentation of osteochondroma in toes-A case report with review of literature

A 23-year-old male presented with long-standing swelling in the middle of the third toe right side with difficulty in wearing footwear. Clinical examination revealed it as bony hard fixed swelling moving with interphalangeal joint movements. Clinical diagnosis of benign bony swelling was made and radiological investigation demonstrated features suggestive of osteochondroma. En-mass excision of the lesion was done, with histo-pathological confirmation of osteochondroma. Although the subungual presentation of osteochondroma or exostosis in toes is quite common, the astounding non-subungual presentation should also be kept in mind as a plausible differential diagnosis of benign bony swelling in toes.

A novel mutation in ext2 caused hereditary multiple exostoses through reducing the synthesis of heparan sulfate

Hereditary multiple exostoses (HME) is a rare skeletal disorder characterized by the formation of multiple benign cartilage-capped tumors, usually in the metaphyseal region of the long bones. Over 70% of HME cases arise from monoallelic mutations in either of the two genes encoding the heparan sulfate (HS) synthesis enzymes, ext1 and ext2. To identify more HME-associated mutations, genomic DNA from members of five independent consanguineous families with HME was sequenced with whole exome sequencing (WES). A novel heterozygous splice site mutation (c.1173+2T>A) in ext2 was detected in all three affected members of family V. Further study showed that the novel mutation caused exon 7 of ext2 mRNA to be skipped during splicing and caused a frameshift after the codon for Arg360, which results in the appearance of new 43 codons, followed by a termination codon. Although the resulting truncated protein was still localized to the Golgi, similar to the full-length EXT2, its HS synthesis activity decreased by 40%. In this study, a novel splice site mutation in ext2 was identified and suggested to be a pathogenic mutation of HME, which may expand the genetic etiology spectrum of HME and may be helpful for clinical genetic counseling and prenatal diagnosis.

Outcomes of Temporary Hemiepiphyseal Stapling for Correcting Genu Valgum in Children with Multiple Osteochondromas: A Single Institution Study

Background: Multiple osteochondromas is a rare skeletal disorder characterized by the presence of osteocartilaginous protrusions causing bony deformities, especially around the knee. Guided growth by temporary hemiepiphyseal stapling is the treatment of choice to correct the deformity by modulating the residual physeal growth of the lower limbs. Although this procedure is increasingly practiced, inconclusive evidence exists regarding its effectiveness in children with multiple osteochondromas. The study aims to compare the outcomes of temporary hemiepiphyseal stapling for correcting genu valgum in children with multiple osteochondromas vs. idiopathic cases. Methods: In this retrospective cohort study, we included patients admitted at a single institution from 2008 to 2018. A total of 97 children (77 idiopathic, 20 multiple osteochondromas) were enclosed, accounting for 184 limbs treated by temporary hemiepiphyseal stapling. We investigated if children with multiple osteochondromas had a similar successful rate of correction, rate of complications, and correction velocity compared to children with idiopathic genu valgum. Results: Overall, 151 limbs (82%) achieved complete correction or overcorrection, with idiopathic cases having a significantly higher rate of success compared to pathologic cases (88% vs. 55%; p < 0.001). In addition, multiple osteochondromas children sustained a higher rate of major complications (p = 0.021) and showed significantly lower correction velocity (p = 0.029). Conclusion: Temporary hemiepiphyseal stapling is effective in both idiopathic and multiple osteochondromas children, although the latter often achieved incomplete correction, had a higher risk of complications, and required a longer time of stapling. We suggest to anticipate the timing of intervention; otherwise, children with multiple osteochondromas and severe valgus deformity, approaching skeletal maturity, could undergo combined femoral and tibial stapling.

The Incidence of Vertebral Exostoses in Multiple Hereditary Exostoses and Recommendations for Spinal Screening

BACKGROUND

Multiple hereditary exostoses (MHE) lead to the development of pedunculated or sessile osteocartilaginous lesions. Vertebral involvement occurs in MHE and encroaching intracanal exostoses can result in devastating consequences. Magnetic resonance imaging (MRI) of the entire spine has been used to screen for vertebral exostoses to detect high-risk patients. The primary purpose of this investigation is to determine the incidence of vertebral and encroaching intracanal exostoses in patients with MHE. A secondary purpose is to determine if pelvis and rib exostoses serve as "harbinger" lesions of vertebral involvement in MHE.

METHODS

A retrospective chart review was performed on 39 patients (21 male and 18 female individuals) with MHE who underwent routine spinal screening with noncontrast entire spine MRI. The average age at screening was 12.3 years (range, 3 to 17 y). Screening was ordered consecutively on patients seen during the study period who were between ages 8 and 18 years or had complaints that could be related to encroaching intracanal exostoses.

RESULTS

The incidence of vertebral exostoses in this cohort of 39 patients with MHE was 28% (11 total). An encroaching intracanal exostosis was seen in 3 patients (2 cervical, 1 thoracic). Nonencroaching vertebral exostoses were discovered in 8 patients. Sufficient pelvis and rib imaging to determine the presence of pelvis and rib exostoses was available in 8 of those with vertebral exostoses and 19 of those with no vertebral exostoses on screening MRI. In this cohort, the sensitivity and specificity of the presence of both pelvis and rib exostoses for determining the presence of spinal involvement in MHE are 88% and 5%, respectively.

CONCLUSIONS

Based on the results of this cohort, vertebral exostoses are common in MHE, and screening MRI of the entire spine can be used to determine which patients need close observation. If a more selective screening protocol is utilized, an entire spine MRI could be obtained for patients who desire increased physical activity levels or for patients with both pelvis and rib exostoses. At a minimum, treating physicians should monitor patients with MHE closely for neurological symptoms and have a low threshold to obtain advanced spinal imaging.

LEVEL OF EVIDENCE

Level III-diagnostic.

Mutation spectrum of EXT1 and EXT2 in the Saudi patients with hereditary multiple exostoses

BACKGROUND

Hereditary Multiple Exostoses (HME), also known as Multiple Osteochondromas (MO) is a rare genetic disorder characterized by multiple benign cartilaginous bone tumors, which are caused by mutations in the genes for exostosin glycosyltransferase 1 (EXT1) and exostosin glycosyltransferase 2 (EXT2). The genetic defects have not been studied in the Saudi patients.

AIM OF STUDY

We investigated mutation spectrum of EXT1 and EXT2 in 22 patients from 17 unrelated families.

METHODS

Genomic DNA was extracted from peripheral leucocytes. The coding regions and intron-exon boundaries of both EXT1 and EXT2 genes were screened for mutations by PCR-sequencing analysis. Gross deletions were analyzed by MLPA analysis.

RESULTS

EXT1 mutations were detected in 6 families (35%) and 3 were novel mutations: c.739G > T (p. E247*), c.1319delG (p.R440Lfs*4), and c.1786delA (p.S596Afs*25). EXT2 mutations were detected in 7 families (41%) and 3 were novel mutations: c.541delG (p.D181Ifs*89), c.583delG (p.G195Vfs*75), and a gross deletion of approximately 10 kb including promoter and exon 1. Five patients from different families had no family history and carried de novo mutations (29%, 5/17). No EXT1 and EXT2 mutations were found in the remaining four families. In total, EXT1 and EXT2 mutations were found in 77% (13/17) of Saudi HME patients.

CONCLUSION

EXT1 and EXT2 mutations contribute significantly to the pathogenesis of HME in the Saudi population. In contrast to high mutation rate in EXT 1 (65%) and low mutation rate in EXT2 (25%) in other populations, the frequency of EXT2 mutations are much higher (41%) and comparable to that of EXT1 among Saudi patients. De novo mutations are also common and the six novel EXT1/EXT2 mutations further expands the mutation spectrum of HME.

Diagnosis, Management, and Treatment Options: A Cervical Spine Osteochondroma Meta-Analysis

Osteochondroma is described as a capped benign bony neoplasm that forms on the outer surface of bone. These tumors affect nearly 6 million people per year. Although osteochondromas most often involve the appendicular skeleton, many involve the spine, with many cases located in the cervical spine. When osteochondromas involve the spine, they can present with a variety of symptoms, including pain, radiculopathy, and myelopathy, which may necessitate surgical treatment. Spinal osteochondromas can be classified into 2 types: multiple osteochondromas in the context of patients with multiple hereditary exostosis (MHE) and solitary osteochondroma or solitary exostosis (SE). Previous reviews have captured only some of the available literature on cervical osteochondromas and have generally focused on either SE or those associated with MHE. The purpose of our review was to provide an extensive review of all previously reported cervical osteochondromas and to compare osteochondroma characteristics, clinical presentation, and outcomes in the context of MHE and SE.

Phalangeal Intra-Articular Osteochondroma Caused a Rare Clinodactyly Deformity in Children: Case Series and Literature Review

BACKGROUND

Various factors are discovered in the development of clinodactyly. The purpose of this retrospective study was to present a group of children with a rare clinodactyly deformity caused by phalangeal intra-articular osteochondroma and evaluate the efficacy of various treatment methods.

METHODS

All child patients that were treated for finger problems in our center between Jan 2017 and Dec 2020 were reviewed. A detailed analysis was made of the diagnosis and treatment methods in eight rare cases. X-rays and histopathology were applied.

RESULTS

A preliminary analysis of 405 patients in total was performed, and we included eight cases in our final analysis. This cohort consisted of 2 girls and 6 boys, with a mean age of 5.74 ± 3.22 years (range: 2y5m to 11y). Overall, four patients had their right hand affected and four patients had their left hand affected. One patient was diagnosed as having hereditary multiple osteochondroma (HMO) while the other seven patients were all grouped into solitary osteochondroma. Osteochondroma was proven in all of them by histopathology examination. Preoperative X-rays were used to allow identification and surgery planning in all cases. All osteochondromas were intra-articular and in the distal end of the phalanges, which is located opposite the epiphyseal growth area. All of the osteochondromas developed in half side of the phalanges. The angulation in the finger long axis was measured, and resulted in a mean angulation of 34.63 ± 24.93 degree (range: 10.16-88.91 degree). All of them received surgery, resulting in good appearance and fingers straightening. No recurrence was recorded.

CONCLUSIONS

This retrospective analysis indicates that 10 degrees can be selected as the angulation level for diagnosis of clinodactyly deformities. What's more important, the abnormal mass proven by X-rays should be included as the classical direct sign for diagnosis. The first choice of treatment is surgery in symptomatic osteochondromas.

Hereditary multiple osteochondromas in Jordanian patients: Mutational and immunohistochemical analysis of EXT1 and EXT2 genes

The aim of the present study was to investigate the molecular characteristics of hereditary multiple osteochondromas (HMO) in a subset of Jordanian patients with a focus on the genetic variants of exostosin (EXT1)/(EXT2) and their protein expression. Patients with HMO and their family members were included. Recorded clinical characteristics included age, sex, tumors number and location, joint deformities and associated functional limitations. Mutational analysis of EXT1 and EXT2 exonic regions was performed. Immunohistochemical staining for EXT1 and EXT2 was performed manually using two different commercially available rabbit anti-human EXT1 and EXT2 antibodies. A total of 16 patients with HMO from nine unrelated families were included, with a mean age of 13.9 years. A total of 75% (12/16) of the patients were male and (69%) (11/16) had a mild disease (class I). EXT mutation analysis revealed only EXT1 gene mutations in 13 patients. Seven variants were detected, among which three were novel: c.1019G>A, p. (Arg340His), c.962+1G>A and c.1469del, p. (Leu490Argfs*9). Of the 16 patients, 3 did not harbor any mutations for either EXT1 or EXT2. Immunohistochemical examination revealed decreased expression of EXT1 protein in all patients with EXT1 mutation. Surprisingly, EXT2 protein was not detected in these patients, although none had EXT2 mutations. The majority of Jordanian patients with HMO, who may represent an ethnic group that is infrequently investigated, were males and had a mild clinical disease course; whereas most patients with EXT1 gene mutations were not necessarily associated with a severe clinical disease course. The role of EXT2 gene remains a subject of debate, since patients with EXT1 mutations alone did not express the non-mutated EXT2 gene.

EXT1 and EXT2 Variants in 22 Chinese Families With Multiple Osteochondromas: Seven New Variants and Potentiation of Preimplantation Genetic Testing and Prenatal Diagnosis

Multiple osteochondromas (MO), the most common type of benign bone tumor, is an autosomal dominant skeletal disorder characterized by multiple cartilage-capped bony protuberances. In most cases, EXT1 and EXT2, which encode glycosyltransferases involved in the biosynthesis of heparan sulfate, are the genes responsible. Here we describe the clinical, phenotypic and genetic characterization of MO in 22 unrelated Chinese families involving a total of 60 patients. Variant detection was performed by means of a battery of different techniques including Sanger sequencing and whole-exome sequencing (WES). The pathogenicity of the missense and splicing variants was explored by means of in silico prediction algorithms. Sixteen unique pathogenic variants, including 10 in the EXT1 gene and 6 in the EXT2 gene, were identified in 18 (82%) of the 22 families. Fourteen (88%) of the 16 variants were predicted to give rise to truncated proteins whereas the remaining two were missense. Seven variants were newly described here, further expanding the spectrum of MO-causing variants in the EXT1 and EXT2 genes. More importantly, the identification of causative variants allowed us to provide genetic counseling to 8 MO patients in terms either of preimplantation genetic testing (PGT) or prenatal diagnosis, thereby preventing the reoccurrence of MO in the corresponding families. This study is the first to report the successful implementation of PGT in MO families and describes the largest number of subjects undergoing prenatal diagnosis to date.

Osteochondroma of the talus: three varying cases

Osteochondroma of the talus is a rare entity that can cause pain, swelling, restriction of movements, synovitis and tarsal tunnel syndrome (TTS). We present three such cases with varying presentation. Case 1 presented with synovitis of the ankle along with a bifocal origin of the talar osteochondroma. Case 2 presented with TTS as a result of compression of the posterior tibial nerve. Case 3 presented with deformity of the foot. In all the three cases, the mass was excised en bloc and histologically proven to be osteochondroma. In case 3, the ankle joint was reconstructed with plate, bone graft and arthrodesis of the inferior tibiofibular joint. All the three cases had good clinical outcomes.

An unusual diagnosis for an usual test

Background

Hereditary multiple osteochondromas (HMO) is a genetic condition characterized by the presence of multiple osteochondromas, usually at the lateral side of the most active growth plate of a long bone. These lesions may persist, be asymptomatic during childhood, and may increase in number and size until growth plates close. Therefore, diagnosis of HMO in children and young people can be challenging; while short stature can be more evident at the onset of puberty, asymptomatic ostheocondromas can progress into different degrees of orthopedic deformity. Moreover, multiple complications may arise due to the presence of osteochondromas, including tendon and compression muscle pain, neurovascular disorders, obstetric problems, scoliosis and malignant transformation into secondary peripheral chondrosarcoma in adulthood.

Case presentation

We report the case of a girl admitted to our Institute for growth delay. While laboratory tests, including growth hormone stimulation test, were normal, left hand X-ray revealed multiple osteochondromas, suggestive for HMO. The genetic test for EXT1 and EXT2 genes confirmed the radiological diagnosis, with a mutation inherited from the mother who displayed the same radiological abnormalities along with recurrent limb pain episodes.

Conclusions

HMO is a genetic condition whose diagnosis can be challenging, especially in females. Every pediatricians should consider a skeletal dysplasia in case of unexplained growth delay and a skeletal survey might be fundamental in reaching a diagnosis.

An analysis of osteoporosis in patients with hereditary multiple exostoses

We analyzed osteoporosis in 20 HME patients. According to the T-score of BMD, 30% and 67.5% of the patients fell in the range of osteopenia in the lumbar spine and femoral neck. Our results indicate HME patients have low bone mass. They do not have abnormal bone metabolism.

INTRODUCTION

There are few reports of osteoporosis in hereditary multiple exostoses (HME) patients. Therefore, the purpose of this study was to analyze osteoporosis in HME patients.

METHODS

This retrospective cohort study included 20 patients diagnosed with HME. Patients underwent bone mineral density (BMD) measurement of the lumbar spine (n = 20) and femoral neck (n = 40). Bone metabolic parameters, including serum osteocalcin and urinary cross-linked N-telopeptide of type 1 collagen (NTx), were analyzed in all subjects. EXT1 and EXT2 genes were sequenced using genomic DNA. We also examined the correlation between genotype and BMD Z-score and T-score.

RESULTS

The mean BMD values of the lumbar spine were 1.085 ± 0.116 g/cm² (n = 11) in male and 1.108 ± 0.088 g/cm² (n = 9) in female. The mean BMD values of the femoral neck area were 0.759 ± 0.125 g/cm² (n = 22) in male and 0.749 ± 0.115 g/cm² (n = 18) in female. Z-score of most HME patients show < 0, indicating that these patients tend to have low bone mass compared with the age-matched population. According to the T-score of BMD, 30% (6 of 20) and 67.5% (27 of 40) of the patients fell in the range of osteopenia in the lumbar spine and femoral neck areas, respectively. Serum osteocalcin and urinary NTx were in the normal range in most patients. There was no significant correlation between genotypes and Z-score.

CONCLUSION

HME patients have low bone mass, especially in the femoral neck area. They do not have abnormal bone metabolism, and there was no correlation between genotypes and Z-score.

Brachymetacarpia and Brachymetatarsia in Patients with Multiple Hereditary Exostosis

Background

Multiple hereditary exostosis is a common autosomal dominant inherited musculoskeletal disorder that manifests with multiple osteochondromas. The clinical manifestations and pathological characteristics of osteochondromas found in the long bone and genetic alterations related to multiple hereditary exostosis have been widely reported. In this study, we investigated the characteristics of brachymetacarpia and brachymetatarsia associated with multiple hereditary exostosis.

Methods

Of the 133 patients with a diagnosis of multiple hereditary exostosis who were recruited from 2005 to 2018, 101 patients who underwent plain radiography after 10 years of age were included. There were 55 male (54.5%) and 46 female (45.5%) patients. Brachymetacarpia or brachymetatarsia was diagnosed when disruption of the Lièvre parabola connecting the metacarpal or metatarsal heads was observed on plain radiographs. Three orthopedic surgeons individually reviewed hand and foot plain radiographs.

Results

Of the 101 patients, 41 patients (40.6%) had more than 1 brachymetacarpia (88 cases) or brachymetatarsia (81 cases). Among 41 cases, 22 (53.7%) were male and 19 (46.3%) were female. The mean age at the time of radiographic evaluation of the hands and feet was 14.6 years (range, 10–63 years). Shortening was most commonly found in the 3rd and 4th metacarpal or metatarsal bones.

Conclusions

We found a relatively high incidence of brachymetacarpia and brachymetatarsia in our patients. Physicians should suspect the presence of brachymetacarpia and brachymetatarsia when treating patients with multiple hereditary exostosis.

Radiographic characteristics of the hip joint in skeletally mature patients with multiple hereditary exostoses

OBJECTIVE

To elucidate the radiological characteristics of the hips, especially in proximal femur, of skeletally mature patients with multiple hereditary exostoses (MHE).

MATERIALS AND METHODS

Fifty eligible patients (100 hips) were included in the study and assigned to the MHE group. The control group included age- and sex-matched individuals, and the radiographs of 100 hips were used as controls. We examined the anatomical characteristics of the acetabulum and the proximal femur, including the acetabular depth-width ratio (ADR), Sharp's angle, femoral neck-shaft angle (NSA), Wiberg's centre-edge angle (CEA), femoral neck axis length (FNAL), femoral head diameter, (FHD), femoral neck width (FNW), femoral shaft width (FSW), femoral neck-shaft angle (NSA), and femoral head-neck ratio (FHNR = FHD/FNW). p value < 0.05 was considered significant.

RESULTS

Osteochondroma was frequently observed in the medial femoral neck (79%), but it was rarely found in the femoral head (1%). ADR and Sharp's angle were not significantly different between the MHE and control groups (p = 0.2056, p = 0.5025). CEA was significantly different between the two groups (p < 0.0001). FNW was significantly larger in the MHE group than in the control group (p < 0.0001). FHNR was significantly different between the two groups (p < 0.0001). NSA was significantly larger than the MHE group (141.8° ± 9.7° vs 129.5° ± 5.6°, p < 0.0001).

CONCLUSIONS

Hip dysplasia in the pelvic side was not commonly observed in skeletally mature MHE patients. However, they showed femoral neck widening and coxa valga. The occurrence of osteochondroma around the femoral neck affects the degree of valgus deformity. These facts could be useful for orthopaedic surgeons treating MHE patients.