Myositis Ossificans

Bizarre parosteal osteochondromatous proliferation in the distal ulna where the lesion is continuous with the medullary cavity: a case report

BACKGROUND

Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare benign bone tumor, it is also called "Nora's lesion". The lesion is characterized by heterotopic ossification of the normal bone cortex or parosteal bone. The etiology of BPOP is unclear and may be related to trauma. In most BPOPs, the lesion is not connected to the medullary cavity. Here we report an atypical case, characterized by reversed features compared to the typical BPOP, which demonstrated continuity of the lesion with the cavity.

CASE PRESENTATION

An 11-year-old female child had a slow-growing mass on her right wrist for 8 months with forearm rotation dysfunction. Plain X-rays showed an irregular calcified mass on the right distal ulna, and computed tomography (CT) showed a pedunculated mass resembling a mushroom protruding into the soft tissue at the distal ulna. The medulla of this lesion is continuous with the medulla of the ulna. A surgical resection of the lesion, together with a portion of the ulnar bone cortex below the tumor was performed, and the final pathology confirmed BPOP. After the surgery, the child's forearm rotation function improved significantly, and there was no sign of a recurrence at 1-year follow-up.

CONCLUSION

It is scarce for BPOP lesions to communicate with the medullary cavity. However, under-recognition of these rare cases may result in misdiagnosis or inappropriate treatment thereby increasing the risk of recurrence. Therefore, special cases where BPOP lesions are continuous with the medulla are even more important to be studied to understand better and master these lesions. Although BPOP is a benign tumor with no evidence of malignant transformation, the recurrence rate of surgical resection is high. We considered the possibility of this particular disease prior to surgery and performed a surgical resection with adequate safety margins. Regular postoperative follow-up is of utmost importance, without a doubt.

Animal models of tendon calcification: Past, present, and future

Tendon calcification is a common clinical condition that frequently occurs as a complication after tendon injury and surgery, or as an expression of fibrodysplasia ossificans progressiva. This condition can be referred to by various names in clinical practice and literature, including tendon ossification, tendon mineralization, heterotopic ossification, and calcific tendonitis. The exact pathogenesis of tendon calcification remains uncertain, but current mainstream research suggests that calcification is mostly cell mediated. To further elucidate the pathogenesis of tendon calcification and to better simulate the overall process, selecting appropriate experimental animal models is important. Numerous animal models have been utilized in various clinical studies, each with its own set of advantages and limitations. In this review, we have discussed the advancements made in research on animal models of tendon calcification, with a focus on the selection of experimental animals, the sites of injury in these models, and the methods employed for modeling.

Ultrasound of palpable lesions: a pictorial review

Ultrasound (US) is the imaging modality of choice for evaluation of superficial palpable lesions. A large proportion of these lesions have characteristic sonographic appearance and can be confidently diagnosed with US without the need for biopsy or other intervention. The Society of Radiologists in Ultrasound (SRU) recently published a Consensus Conference Statement on superficial soft tissue masses. The goal of this manuscript is (a) to serve as a sonographic pictorial review for palpable lesions based on the SRU statement, (b) present the typical sonographic features of palpable lesions that can be confidently diagnosed with US, and (c) provide an overview of other palpable lesions with a framework to interpret the US studies and advise on appropriate further management.

Genetic regulation of injury-induced heterotopic ossification in adult zebrafish

Heterotopic ossification is the inappropriate formation of bone in soft tissues of the body. It can manifest spontaneously in rare genetic conditions or as a response to injury, known as acquired heterotopic ossification. There are several experimental models for studying acquired heterotopic ossification from different sources of damage. However, their tenuous mechanistic relevance to the human condition, invasive and laborious nature and/or lack of amenability to chemical and genetic screens, limit their utility. To address these limitations, we developed a simple zebrafish injury model that manifests heterotopic ossification with high penetrance in response to clinically emulating injuries, as observed in human myositis ossificans traumatica. Using this model, we defined the transcriptional response to trauma, identifying differentially regulated genes. Mutant analyses revealed that an increase in the activity of the potassium channel Kcnk5b potentiates injury response, whereas loss of function of the interleukin 11 receptor paralogue (Il11ra) resulted in a drastically reduced ossification response. Based on these findings, we postulate that enhanced ionic signalling, specifically through Kcnk5b, regulates the intensity of the skeletogenic injury response, which, in part, requires immune response regulated by Il11ra.

Myositis Ossificans Traumatica of Bilateral Sternocleidomastoid Muscles After Chiropractor Adjustment: A Case Report

A woman in her 20s with a past medical history of surgical debulking of a right neck mass presented to the hospital for persistent and worsening right shoulder pain. The shoulder pain was associated with trismus and back and neck pain. A CT scan of the neck with contrast revealed post-surgical changes with increased heterotopic ossification throughout the surgical site extending to the supraclavicular soft tissues and the left sternocleidomastoid muscle, suggesting muscle ossification. A biopsy was performed, and the patient was diagnosed with myositis ossificans (MO). Initial treatment began with the administration of steroids and analgesics. She was scheduled for a follow-up with orthopedics, rheumatology, and genetics, but she was lost for follow-up. MO is a very rare medical condition usually associated with trauma, and in our patient, the symptoms started after a chiropractic adjustment.

Ossifying fasciitis of the proximal lower extremity

Ossifying fasciitis is a rare benign tumor of heterotopic bone formation within fascial tissue. We present a case of a 23-year-old female with a nontraumatic painful mass of the left proximal thigh identified as ossifying fasciitis, a lesion that must be considered in the differential diagnosis of soft tissue tumors.

Imaging diagnosis and differential diagnosis of extraskeletal osteosarcoma

OBJECTIVE

The aim of this study was to investigate the clinical, imaging and pathological features of extraskeletal osteosarcoma (EOS) and to improve the understanding of this disease and other similar lesions.

METHODS

The data for 11 patients with pathologically confirmed extraosseous osteosarcoma, including tumour site and size and imaging and clinical manifestations, were analysed retrospectively.

RESULTS

Six patients were male (60%), and 5 were female (40%); patient age ranged from 23 to 76 years (average age 47.1 years). Among the 11 patients, 7 had clear calcifications or ossification with different morphologies, and 2 patients showed a massive mature bone tumour. MRI showed a mixed-signal mass with slightly longer T1 and T2 signals in the tumour parenchyma. Enhanced CT and MRI scans showed enhancement in the parenchyma. Ten patients had different degrees of necrosis and cystic degeneration in the mass, 2 of whom were complicated with haemorrhage, and MRI showed "fluid‒fluid level" signs. Of the 11 patients, five patients survived after surgery, and no obvious recurrence or metastasis was found on imaging examination. One patient died of lung metastasis after surgery, and 2 patients with open biopsy died of disease progression. One patient died of respiratory failure 2 months after operation. 2 patients had positive surgical margins, and 1 had lung metastasis 6 months after operation and died 19 months after operation. Another patient had recurrence 2 months after surgery.

CONCLUSION

The diagnosis of EOS requires a combination of clinical, imaging and histological examinations. Cystic degeneration and necrosis; mineralization is common, especially thick and lumpy mineralization. Extended resection is still the first choice for localized lesions. For patients with positive surgical margins or metastases, adjuvant chemoradiotherapy is needed.

Myositis ossificans in the pediatric population: a systematic scoping review

Introduction

Circumscribed or pseudomalignant myositis ossificans (MO) is a rare and benign condition characterized by heterotopic bone formation in soft tissues. The clinical presentation of MO, imaging investigations, histological findings, and treatment strategies are unclear, especially in the pediatric population.

Materials and methods

A literature search was conducted in PubMed, Scopus, and Google Scholar electronic databases to identify original articles and reviews in English or French of traumatic and non-traumatic MO. Studies were selected by 2 independent reviewers following the PRISMA recommendation and descriptive data were extracted. We harvest in each case the sex, age at diagnosis, location, presence of initial trauma, pre-emptive diagnosis, modalities of imagery used, realized biopsy, treatment performed, and type of follow-up.

Results

Sixty pediatric cases of MO were identified between 2002 and 2023. Twenty-three patients (38.3%) were diagnosed with idiopathic/pseudomalignant and 37 patients (61.7%) with circumscribed. The mean age at diagnosis was 9.5 years (range 0.2-17 years), with a male-to-female ratio of 1:1. The initial pre-emptive diagnosis was neoplasia in 13 patients (21.7%). The biopsy was percutaneous in 9 patients (15%) and incisional in 7 patients (11.7%). Histological analysis was achieved in 35 cases (57%). Surgical excision was the first line treatment in 46.7% of patients, and non-surgical in the remaining patients. The follow-up strategy was clinical in 16 patients (26.7%) or based on imaging investigation in 23 patients (38.3%).

Discussion

Although MO in children is described as a rare pathology, identifying the benignity of the condition is essential to avoid unnecessary invasive treatment and to avoid delaying the treatment of a potentially life-threatening entity. It seems that there is no consensus established concerning the proper imaging for diagnosis. Clinicians should acknowledge that the absence of a triggering trauma tends to direct the investigation and the management toward a surgical attitude. Conservative management is key, however, surgical excision can be proposed on matured lesions on a case-by-case basis. The absence of recurrence is not excluded. Therefore, a close clinical follow-up is suggested for all cases. The true benefit of a radiological is questioned in a question known to be self-resolving.

Broca's area, variation and taxic diversity in early Homo from Koobi Fora (Kenya)

Because brain tissues rarely fossilize, pinpointing when and how modern human cerebral traits emerged in the hominin lineage is particularly challenging. The fragmentary nature of the fossil material, coupled with the difficulty of characterizing such a complex organ, has been the source of long-standing debates. Prominent among them are the uncertainties around the derived or primitive state of the brain organization in the earliest representatives of the genus Homo, more particularly in key regions such as the Broca's area. By revisiting a particularly well-preserved fossil endocast from the Turkana basin (Kenya), here we confirm that early Homo in Africa had a primitive organization of the Broca's area ca. 1.9 million years ago. Additionally, our description of KNM-ER 3732 adds further information about the variation pattern of the inferior frontal gyrus in fossil hominins, with implications for early Homo taxic diversity (i.e. one or two Homo species at Koobi Fora) and the nature of the mechanisms involved in the emergence of derived cerebral traits.

Woven bone formation and mineralization by rat mesenchymal stromal cells imply increased expression of the intermediate filament desmin

Background

Disordered and hypomineralized woven bone formation by dysfunctional mesenchymal stromal cells (MSCs) characterize delayed fracture healing and endocrine -metabolic bone disorders like fibrous dysplasia and Paget disease of bone. To shed light on molecular players in osteoblast differentiation, woven bone formation, and mineralization by MSCs we looked at the intermediate filament desmin (DES) during the skeletogenic commitment of rat bone marrow MSCs (rBMSCs), where its bone-related action remains elusive.

Results

Monolayer cultures of immunophenotypically- and morphologically - characterized, adult male rBMSCs showed co-localization of desmin (DES) with vimentin, F-actin, and runx2 in all cell morphotypes, each contributing to sparse and dense colonies. Proteomic analysis of these cells revealed a topologically-relevant interactome, focused on cytoskeletal and related enzymes//chaperone/signalling molecules linking DES to runx2 and alkaline phosphatase (ALP). Osteogenic differentiation led to mineralized woven bone nodules confined to dense colonies, significantly smaller and more circular with respect to controls. It significantly increased also colony-forming efficiency and the number of DES-immunoreactive dense colonies, and immunostaining of co-localized DES/runx-2 and DES/ALP. These data confirmed pre-osteoblastic and osteoblastic differentiation, woven bone formation, and mineralization, supporting DES as a player in the molecular pathway leading to the osteogenic fate of rBMSCs.

Conclusion

Immunocytochemical and morphometric studies coupled with proteomic and bioinformatic analysis support the concept that DES may act as an upstream signal for the skeletogenic commitment of rBMSCs. Thus, we suggest that altered metabolism of osteoblasts, woven bone, and mineralization by dysfunctional BMSCs might early be revealed by changes in DES expression//levels. Non-union fractures and endocrine - metabolic bone disorders like fibrous dysplasia and Paget disease of bone might take advantage of this molecular evidence for their early diagnosis and follow-up.

Fibroblastic and Myofibroblastic Soft-Tissue Tumors: Imaging Spectrum and Radiologic-Pathologic Correlation

Fibroblastic and myofibroblastic tumors are a variable group of neoplasms ranging from benign to malignant. These lesions may affect patients of any age group but are more frequently encountered in the pediatric population. Patient clinical presentation depends on the location, growth pattern, adjacent soft-tissue involvement, and pathologic behavior of these neoplasms. In the 2020 update to the World Health Organization (WHO) classification system, these tumors are classified on the basis of their distinct biologic behavior, histomorphologic characteristics, and molecular profiles into four tumor categories: (a) benign (eg, fibrous hamartoma of infancy, nodular fasciitis, proliferative fasciitis, fibroma of the tendon sheath, calcifying aponeurotic fibroma); (b) intermediate, locally aggressive (eg, desmoid fibromatosis); (c) intermediate, rarely metastasizing (eg, dermatofibrosarcoma protuberans, myxoinflammatory fibroblastic sarcoma, low-grade myofibroblastic sarcoma, infantile fibrosarcoma); and (d) malignant (eg, sclerosing epithelioid fibrosarcomas; low-grade fibromyxoid sarcoma; myxofibrosarcoma; fibrosarcoma, not otherwise specified). Detection of various components of solid tumors at imaging can help in prediction of the presence of corresponding histopathologic variations, thus influencing diagnosis, prognosis, and treatment planning. For example, lesions with a greater myxoid matrix or necrotic components tend to show higher signal intensity on T2-weighted MR images, whereas lesions with hypercellularity and dense internal collagen content display low signal intensity. In addition, understanding the radiologic-pathologic correlation of soft-tissue tumors can help to increase the accuracy of percutaneous biopsy and allow unnecessary interventions to be avoided. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Osório CAB, Bitencourt AGV, Makdissi FBA, do Nascimento AG. Myositis Ossificans of the Breast Mimicking Breast Cancer: A Case Report

Myositis ossificans (MO) is an uncommon tumor characterized by a rapidly growing mass following a history of local trauma. Few cases of MO affecting the breast have been reported, and some were misdiagnosed as primary osteosarcoma of the breast or metaplastic breast carcinoma. The following case report presents a patient with a growing breast lump whose core biopsy result was suspicious for breast cancer. MO was diagnosed after analysis of the mastectomy specimen. This case highlights the importance of MO as a differential diagnosis of a growing soft-tissue mass after trauma to avoid unnecessary overtreatment. Keywords: Myositis Ossificans, Osteosarcoma, Breast Cancer, Mastectomy, Heterotopic Ossification © RSNA, 2023.

An Unusual Case of Severe Trismus After Craniotomy

Myositis ossificans Traumatica (MOT) is a non-neoplastic, heterotrophic ossifying disease process in muscle and soft tissue rarely involving the craniofacial area. Treatment depends on the extent of ossification and functional limitations. We present the first case of MOT of the temporalis muscle following neurosurgical intervention. This is the case of a 28-year-old male patient who underwent numerous neurosurgical interventions and reported progressive trismus following these interventions. Imaging demonstrated a right temporal region radio-opacity consistent with ossification of the temporalis muscle. The patient underwent coronoidectomy with excision of the ossified right temporalis muscle and reconstruction with an anterolateral thigh adipofascial vascular free flap. Postoperatively, he maintained intact function with increased incisal opening and no cosmetic defects. Limited mouth opening after the neurological procedure has a wide differential, and MOT must be considered. Surgical repair and reconstruction are multifaceted problems. Free flap reconstruction should be considered in multiple operated patients.

Myositis Ossificans of the Trapezius Muscle: A Case Report and Literature Review

Myositis ossificans (MO) is a benign, self-limiting, and nonneoplastic lesion involving the skeletal muscle or soft tissue, rarely occurring in the head and neck. It is relatively rare in clinical practice, and it is difficult to distinguish specific cases from musculoskeletal conditions, which poses unique challenges for clinical diagnosis and treatment. We reported that a 9-year-old boy suffered from local and nontraumatic MO of the trapezius muscle. Given the rarity of this case, the present article detailed the diagnosis and treatment of this rare case and reviewed the relevant literature on MO, focusing on the clinical, pathological, and radiographic characteristics of MO. Notably, these investigations aimed to enhance clinicians' understanding of the disease and improve diagnostic accuracy.

Painful and restricted hip due to myositis ossificans circumscripta of the pectineus muscle after pelvic fracture: A case report

RATIONALE

Myositis ossificans circumscripta (MOC) is a rare disorder that causes heterotopic bone formation in soft tissues. It usually occurs after trauma and affects large muscles of the extremities. MOC of the pectineus muscle is extremely rare and has not been reported to be treated surgically.

PATIENT CONCERNS

A 52-year-old woman presented with left hip pain and dysfunction 4 months after a traffic accident that caused pelvic and humeral fractures and cerebral hemorrhage.

DIAGNOSES

Radiological imaging revealed isolated ossification of the left pectineus muscle. The patient was diagnosed with MOC.

INTERVENTIONS

The patient underwent surgical resection of the ossified pectineus muscle followed by local radiation and medical therapy.

OUTCOMES

At 12 months postoperatively, she was asymptomatic and had normal hip function. No recurrence was observed on radiography.

LESSONS

MOC of the pectineus muscle is a rare condition that can cause severe hip dysfunction. Surgical resection combined with radiation and anti-inflammatory drugs can be an effective treatment option for patients who do not respond to conservative management.

A rare femoral heterotopic bone formation in a 14th-19th century female skeleton from Constância (Portugal)

OBJECTIVE

This paper aims to: (1) document a rare femoral heterotopic ossification (HO), and (2) discuss its aetiology and impact on the individual's locomotion and daily living activities.

MATERIALS

Adult female skeleton (SG.14-SK.7) from the village of Constância (Portugal), and dated from the 14th-19th centuries CE.

METHODS

The biological profile and the macroscopic analysis of the bone changes were assessed using standardized methods.

RESULTS

The macroscopic analysis revealed a large bony mass (8 cm length) located immediately inferior to the small trochanter of the right femur. The lesion exhibited a compact, tubular appearance located at the site of attachment of the pectineus muscle. No signs of bone fracture were observed.

CONCLUSIONS

The morphology of the SG.14-SK.7 femoral lesion is compatible with a probable case of myositis ossificans traumatica (MOT), secondary to acute trauma of the pectineus muscle. The underlying trauma episode, such as random accidental and/or occupation-related injury, is unknown. However, it is highly possible that this self-limiting condition significantly impaired the individual's daily life and mobility.

SIGNIFICANCE

Evidence of severe acute muscle trauma is a rare finding compared with HO secondary to bone trauma and other minor muscle injuries. Moreover, no cases of MOT affecting the pectineus muscle have been reported in the paleopathological literature to date.

LIMITATIONS

Although unlikely, a case of neurogenic or burn-related HO cannot be completely disregarded. It was not possible to undertake radiography as part of this study.

SUGGESTIONS FOR FURTHER RESEARCH

The use of imaging techniques to complement the paleopathological description is advised.

Multimodality imaging features of USP6-associated neoplasms

Since the discovery of USP6 gene rearrangements in aneurysmal bone cysts nearly 20 years ago, we have come to recognize that there is a family of USP6-driven mesenchymal neoplasms with overlapping clinical, morphologic, and imaging features. This family of neoplasms now includes myositis ossificans, aneurysmal bone cyst, nodular fasciitis, fibroma of tendon sheath, fibro-osseous pseudotumor of digits, and their associated variants. While generally benign and in many cases self-limiting, these lesions may undergo rapid growth, and be confused with malignant bone and soft tissue lesions, both clinically and on imaging. The purpose of this article is to review the imaging characteristics of the spectrum of USP6-driven neoplasms, highlight key features that allow distinction from malignant bone or soft tissue lesions, and discuss the role of imaging and molecular analysis in diagnosis.

Imaging of Muscle Injuries

Ultrasound (US) and MR imaging are the most common imaging modalities used to assess sports muscle injuries. The site of the muscle injury can be located at the peripheral aspect of the muscle (myofascial), within the muscle belly (musculotendinous), and with tendon involvement (intratendinous). Tears that affect the intramuscular tendon have a worse prognosis in terms of recovery time. US is an excellent method to evaluate muscle injuries, with high spatial and contrast resolution. MR imaging can be reserved for evaluation of professional athletes, surgical planning, differential diagnosis, and assessment of deep located and proximal muscle groups.

Interleukin 6 promotes BMP9-induced osteoblastic differentiation through Stat3/mTORC1 in mouse embryonic fibroblasts

Interleukin 6 (IL-6) plays a dual role in regulating bone metabolism, although the concrete mechanism is unclear. Bone morphogenetic protein 9 (BMP9) is one of the most potent osteogenic inducers, and a promising alternative for bone tissue engineering. The relationship between IL-6 and BMP9 in osteogenic differentiation remains to be elucidated, and the osteoblastic potential of BMP9 needs to be enhanced to overcome certain shortcomings of BMP9. In this study, we used real-time PCR, western blot, immunofluorescent stain, fetal limb culture and cranial defects repair model to explore the IL-6 role in BMP9-induced osteogenic differentiation in mouse embryonic fibroblasts (MEFs). We found that the rat serum level of IL-6 was increased in the dexamethasone-induced osteoporosis model, and IL-6 expression was detectable in several progenitor cells and MEFs. BMP9 upregulated IL-6 in MEFs, and the BMP9-induced osteoblastic markers were elevated by IL-6, but reduced by IL-6 knockdown. BMP9 and/or IL-6 both activated mTOR, and the IL-6 effect on BMP9-induced osteoblastic markers and bone formation were reduced greatly by mTOR inhibition. Raptor was up-regulated by IL-6 and/or BMP9 specifically, and the osteoblastic markers induced by IL-6 and/or BMP9 were reduced by Raptor knockdown. Meanwhile, Stat-3 was activated by IL-6 and/or BMP9, and the increase of Raptor or osteoblastic markers by IL-6 and/or BMP9 were reduced by Stat-3 inhibition. The Raptor promoter activity was regulated by p-Stat-3. Our finding suggested that IL-6 can promote the BMP9 osteoblastic potential, which may be mediated through activating Stat-3/mTORC1 pathway.

Case Report: Extraskeletal osteosarcoma with preceding myositis ossificans

Extraskeletal osteosarcoma (EO) is a soft tissue sarcoma characterized by the production of bone matrix by neoplastic cells. Benign osteoid in EO, leading to a diagnostic dilemma, is rarely encountered. Herein, for the first time, we present a case with cytogenetically confirmed EO combined with or preceding myositis ossificans (MO). A 21-year-old man had a mildly painful swelling in his left knee. Imaging studies demonstrated a 39-mm mass with peripheral mineralization and cystic change on the posterolateral side of the left fibular head. He was clinically suspected of having either MO or a malignancy, such that wide resection was performed. Macroscopically, the mass was grayish to brown. In the cut section, multiple cystic lesions in addition to solid components were noted. Histopathologically, the solid components demonstrated diffuse proliferation of pleomorphic tumor cells with osteoclast-like giant cells. The malignant tumor cells formed osteoid. In the periphery, the mass was benign, showing mature bone tissue and focally non-malignant woven bone with fibroblasts, compatible with zonation. Fluorescence in situ hybridization (FISH) demonstrated split signals of the USP6 gene. These findings suggested EO with preceding MO. Although the pathogenesis remains to be elucidated, the observed USP6 rearrangement might contribute to both the diagnosis of EO with preceding MO and an understanding of the underlying histopathology.

Myositis ossificans circumscripta after surgery and radiotherapy and during sunitinib treatment: a case report

BACKGROUND

Myositis ossificans circumscripta is a self-limiting, benign, ossifying lesion that can affect any type of soft tissue. It is most commonly found in muscles as a solitary lesion. A history of recent trauma has been reported in approximately 50% of cases. Clinically, MOC presents as a painful swelling, which rapidly increases in size. The pain and inflammatory symptoms spontaneously disappear after approximately 2-6 weeks, and the mass stabilizes or decreases. Radiologically, myositis ossificans circumscripta can be divided into two phases. The first is the acute phase, which is followed by the mature phase 2-6 weeks later. During the acute phase, the radiological aspect does not show any specific abnormality. In the mature phase, plain radiographs and computed tomography show blurred calcifications around a hypodense center. We describe here the first case of myositis ossificans circumscripta, with appropriate follow-up, occurring during sunitinib exposure.

CASE PRESENTATION

We report a case of myositis ossificans circumscripta in a 34-year-old man (ethnicity unknown) receiving sunitinib for metastatic alveolar soft part sarcoma of the left thigh after surgery and radiotherapy. Four months after the first dose of sunitinib, the patient experienced painful swelling in the surgical scar area. Magnetic resonance imaging showed diffuse and marked edema of the anterior compartment of the thigh, without nodular lesions circumscribing a central core, and without bone signal abnormality. The increased visibility of the intermuscular fascia and convergence of normal muscle fibers (black hole effect), without the displacement seen in tumors, were suggestive of myositis. Therefore, antiangiogenic treatment was discontinued, and the symptoms rapidly resolved within a few days. Three weeks after the discontinuation of sunitinib, the inflammatory findings completely disappeared. Two months after the diagnosis of myositis ossificans circumscripta, plain radiographs and computed tomography showed an extensive calcified mass measuring > 12 cm. The continuation of favorable clinical outcomes was confirmed.

CONCLUSIONS

To the best of our knowledge, this is the first case of myositis ossificans circumscripta with appropriate follow-up occurring during sunitinib exposure. Owing to multimodal treatment of sarcoma, we cannot rule out the radiotherapy and surgery causality.

Aggressive atraumatic myositis ossificans in a toddler

Myositis ossificans (MO) is a benign disorder where bone forms within muscles or other soft tissues. This condition usually follows trauma and is rare in pediatric patients. Here we present the case of a 2-year-old male who developed MO of his right elbow without obvious trauma to the area. Imaging of MO in the initial phase is highly unspecific and obtaining tissue samples through a biopsy can render misleading reports. In most cases MO is a self-limited process with complete resolution, however, some cases may present a diagnostic and therapeutic challenge.

Management of bilateral pterygoid myositis ossificans-like lesion in dogs

Myositis ossificans (MO) and myositis ossificans-like lesions have been rarely described within the veterinary literature, and are even less common in the maxillofacial region. When MO affects the muscles of mastication, it can result in complete or partial inability to open the mouth. As with other conditions resulting in decreased or restricted mandibular range of motion, severe and potentially fatal sequelae such as difficulty with prehension, swallowing, and air exchange are possible. Diagnostic imaging is essential in achieving an accurate diagnosis and in formulating an appropriate treatment plan. In this “method” manuscript, we provide a detailed description of our approach to diagnosis and surgical management of MO-like lesions of the pterygoid muscles and describe our experience with two young French bulldogs.

Case Report: Unable to Jump Like a Kangaroo Due to Myositis Ossificans Circumscripta

A male 10-year-old captive red kangaroo (Macropus rufus) was presented with a chronic progressive pelvic limb lameness and reluctance to jump. The general examination revealed a palpable induration of the lumbar epaxial muscles. Magnetic resonance imaging performed under general anesthesia revealed bilateral almost symmetric, well-circumscribed mass lesions in superficial erector spinae muscles. The lesions had irregular to multilobulated appearance with hyper-, hypo-, and isointense areas in T2- and T1-weighted (w) sequences without contrast enhancement. On computed tomography, a peripheral rim of mineralization was apparent. Histopathological analysis of a muscle biopsy showed osseous trabeculae with rare clusters of chondrocytes indicating metaplasia of muscle tissue to bone. No indications of inflammation or malignancy were visible. The clinical, histopathological, and imaging workup of this case was consistent with myositis ossificans circumscripta. This disorder is particularly well-known among human professional athletes such as basketball players, where excessive, chronic-repetitive force or blunt trauma causes microtrauma to the musculature. Metaplasia of muscle tissue due to abnormal regeneration processes causes heterotopic ossification. The kangaroo's clinical signs improved with cyto-reductive surgery, cage rest, weight reduction, and meloxicam without further relapse.

Non‐traumatic myositis ossificans circumscripta in the anterior abdominal wall of a seven‐year‐old Ugandan child: A case report

Myositis ossificans circumscripta (MOC) is a benign and self‐limiting heterotopic ossification in the subcutaneous fat, tendons, muscles, and nerves. It is commonly due to trauma and is frequently encountered in the arm, shoulder, thigh, and hand which are prone to trauma. Non‐traumatic MOC arising from the abdominal muscles is extremely rare. We report a case of 7‐year‐old male child with a three‐year history of progressive painless abdominal swelling in the left hypochondria region with no history of associated trauma. CT scan of the abdomen showed a well‐defined hyperdense mass in the left external oblique muscle. Histological diagnosis confirmed myositis ossificans of the external oblique muscle. The mass was removed surgically with no immediate or late complications.

Non‐traumatic MOC of the abdominal muscles is very rare. Radiological investigations are crucial in the diagnosis and for differentiating a MO lesion from other malignant soft‐tissue tumors as we demonstrated in this case report.

Oncological and Functional Outcomes after Hemicortical Resection and Biological Reconstruction Using Allograft for Parosteal Osteosarcoma of the Distal Femur

Background

Parosteal osteosarcoma (PAOS) is a surface osteosarcoma. Treatment options include wide excision and endoprosthetic or allograft. However, due to the low local recurrence and metastasis rate, when it appears in the posterior surface of the distal femur, the lesion can be managed with hemicortical wide resection and biological reconstruction with hemicortical allograft. The purpose of this study is to evaluate the oncological and functional outcomes of patients with parosteal osteosarcoma (PAOS) of the posterior cortex of the distal femur who underwent biological reconstruction after hemicortical resection.

Methods

Eleven patients who underwent wide tumor resection and defect reconstruction of the posterior surface of the distal femur using hemicortical allograft were retrospectively studied. Local recurrence, metastasis, complications, and the functional outcome using the Musculoskeletal Tumor Society (MSTS) scoring system were evaluated.

Results

The average postoperative follow-up period was 53.64 months (range, 30 to 84 months). At the latest follow-up, all patients had no evidence of disease without metastases. One patient with local recurrence underwent revision surgery with fibula autograft reconstruction. The mean MSTS score was 93.45 ± 3.56.

Conclusions

Treatment of patients with PAOS of the posterior aspect of the distal femur with hemicortical resection and allograft reconstruction has satisfactory oncological and functional outcome and low complication rates.

Giant nontraumatic myositis ossificans in a child: A case report

BACKGROUND

Nontraumatic myositis ossificans is a rare disease whose specific pathogenesis is unclear. Early diagnosis of this disease is very difficult in children because of difficulties in determining medical history and nonspecific early clinical manifestations, which may lead to the failure of timely and effective diagnosis and treatment in some patients. We report the diagnosis and treatment of a child with nontraumatic myositis ossificans and summarize the clinical characteristics and diagnosis and treatment of the disease.

CASE SUMMARY

An 8-year-old girl first came to our hospital for more than a week with pain in the right lower limb. There was no history of trauma or strenuous activities. On physical examination, no mass on the right thigh was found, and the movement of the right lower extremity was limited. Ultrasonography showed synovitis of the hip, and bed rest was recommended. Three days later, the child’s pain persisted and worsened, accompanied by fever and other discomforts. She came to our hospital again and a mass was found on the right thigh with redness and swelling on the surface. The images showed a soft tissue tumor on the right thigh with calcification. Routine blood tests revealed that the inflammation index was significantly increased. In case of infection, the patient was given antibiotics, and the pain was relieved soon after, without fever. However, the right thigh mass persisted and hardened. The patient underwent incision biopsy more than 1 mo later, and the postoperative pathology showed nontraumatic myositis ossificans. After approximately 9 mo of observation, the tumor still persisted, which affected the life of the child, and then resection was performed. Since follow-up, there has been no recurrence.

CONCLUSION

Due to the difficulty in discerning a child's medical history and the diverse early manifestations, it is difficult to diagnose nonossifying muscle disease in children in its early stage. Measures such as timely follow-up and periodic image monitoring are conducive to early diagnosis of the disease. The disease has a certain degree of self-limitation, and it can be observed and treated first. If the tumor persists in the later stage or affects functioning, then surgery is considered.

Giant nontraumatic myositis ossificans in a child: A case report

BACKGROUND

Nontraumatic myositis ossificans is a rare disease whose specific pathogenesis is unclear. Early diagnosis of this disease is very difficult in children because of difficulties in determining medical history and nonspecific early clinical manifestations, which may lead to the failure of timely and effective diagnosis and treatment in some patients. We report the diagnosis and treatment of a child with nontraumatic myositis ossificans and summarize the clinical characteristics and diagnosis and treatment of the disease.

CASE SUMMARY

An 8-year-old girl first came to our hospital for more than a week with pain in the right lower limb. There was no history of trauma or strenuous activities. On physical examination, no mass on the right thigh was found, and the movement of the right lower extremity was limited. Ultrasonography showed synovitis of the hip, and bed rest was recommended. Three days later, the child’s pain persisted and worsened, accompanied by fever and other discomforts. She came to our hospital again and a mass was found on the right thigh with redness and swelling on the surface. The images showed a soft tissue tumor on the right thigh with calcification. Routine blood tests revealed that the inflammation index was significantly increased. In case of infection, the patient was given antibiotics, and the pain was relieved soon after, without fever. However, the right thigh mass persisted and hardened. The patient underwent incision biopsy more than 1 mo later, and the postoperative pathology showed nontraumatic myositis ossificans. After approximately 9 mo of observation, the tumor still persisted, which affected the life of the child, and then resection was performed. Since follow-up, there has been no recurrence.

CONCLUSION

Due to the difficulty in discerning a child's medical history and the diverse early manifestations, it is difficult to diagnose nonossifying muscle disease in children in its early stage. Measures such as timely follow-up and periodic image monitoring are conducive to early diagnosis of the disease. The disease has a certain degree of self-limitation, and it can be observed and treated first. If the tumor persists in the later stage or affects functioning, then surgery is considered.

Management of anterior thigh injuries in soccer players: practical guide

Most of the anterior thigh injuries are contusions or strains, however, some of these injuries can be career ending. Early diagnosis and correct treatment are key to successful outcome. Analyzing injury mechanism and adding both clinical and imaging findings, clinicians can make the right treatment decisions already often in the acute phase of the injury. Low grade contusions and muscle strains are treated well with planned rehabilitation, but complete tendon injuries or avulsions can require operative treatment. Also, neglected minor injuries could lead to chronic disabilities and time lost from play. Typical clinical presentation of anterior thigh injury is swelling and pain during hip flexion or knee extension. In more severe cases a clear gap can be palpated. Imaging methods used are ultrasound and magnetic resonance imaging (MRI) which are helpful for clinicians to determine more exact the extent of injury. MRI can identify possible tendon retractions which may need surgery. Clinicians should also be aware of other traumatic lesions affecting anterior thigh area such as myositis ossificans formation. Optimal treatment should be coordinated including acute phase treatment with rest, ice, and compression together with designed return-to-play protocol. The anatomical structure involved lines the treatment pathway. This narrative review describes these more common reasons for outpatient clinical visits for anterior thigh pain and injuries among soccer players.

Periarticular calcifications

Periarticular calcification and ossification is a frequent finding on imaging and may sometimes pose a diagnostic challenge. The differential diagnoses for this radiological finding are wide and can be classified into broad groups such as idiopathic, developmental, trauma, burns, infection, tumor, connective tissue disease, crystalline, metabolic, vascular, and foreign bodies. With careful consideration of the clinical and imaging findings as well as awareness of mimickers of periarticular mineralization, the list of differential diagnoses can be narrowed down. This article aims to review the clinical-radiologic findings of periarticular calcified or ossified lesions with relevant imaging illustrations.

Return to play after treating acute muscle injuries in elite football players with radial extracorporeal shock wave therapy

Background

To compare lay-off times achieved by treating acute muscle injuries in elite football players with a multimodal therapy approach that includes a specific protocol of almost daily radial extracorporeal shock wave therapy (rESWT) with corresponding data reported in the literature.

Methods

We performed a retrospective analysis of treatments and recovery times of muscle injuries suffered by the players of an elite football team competing in the first/second German Bundesliga during one of the previous seasons.

Results

A total of 20 acute muscle injuries were diagnosed and treated in the aforementioned season, of which eight (40%) were diagnosed as Type 1a/muscular tightness injuries, five (25%) as Type 2b/muscle strain injuries, four (20%) as Type 3a/partial muscle tear injuries and three (15%) as contusions. All injuries were treated with the previously mentioned multimodal therapy approach. Compared with data reported by Ekstrand et al. (Br J Sports Med 47:769–774, 2013), lay-off times (median/mean) were shortened by 54% and 58%, respectively, in the case of Type 1a injuries, by 50% and 55%, respectively, in the case of Type 2b injuries as well as by 8% and 21%, respectively, in the case of Type 3a injuries. No adverse reactions were observed.

Conclusions

Overall, the multimodal therapy approach investigated in this study is a safe and effective treatment approach for treating Type 1a and 2b acute muscle injuries amongst elite football players and may help to prevent more severe, structural muscle injuries.

Fibro-Osseous Pseudotumor

Fibro-osseous pseudotumor is an extremely rare subcutaneous benign ossifying lesion associated with bone formation that is most commonly seen in the hands, followed by the toes. Because the tumor has a certain degree of invasiveness, it is often mistaken for malignancy, which leads to radical, excessive treatment. Our case involved a 32-year-old man with lesions on the left index finger. We documented the detailed data of diagnosis, treatment, and follow-up. We also conducted a review and summarized the published cases to advance our understanding of the disease, provide more accurate diagnostic criteria, and avoid inappropriate surgical procedures. [Orthopedics. 2021;44(6):e713-e718.].

Surface bone sarcomas: an update on current clinicopathological diagnosis and treatment

Surface bone sarcomas are rare malignant bone tumours. Osseous and cartilaginous surface bone sarcomas are the most common, with parosteal and periosteal osteosarcomas, periosteal chondrosarcomas and secondary peripheral chondrosarcomas being the most frequent.

Their clinical symptoms are non-specific and include pain for several months, swelling and limited range of motion of the adjacent joints.

Prompt diagnosis is important, as biological behaviour, imaging and histopathologic characteristics, treatment and prognosis differ considerably from their conventional intramedullary counterparts. Moreover, their imaging characteristics are not infrequently non-characteristic and may be misinterpreted as juxtacortical benign lesions leading to incorrect diagnosis and treatment, with life-threatening repercussions. Molecular studies and histopathological sampling are essential for accurate diagnosis.

There are still numerous issues regarding the biology, pathophysiology and treatment options of these entities due to their rarity.

Cite this article: EFORT Open Rev 2021;6:905-917. DOI: 10.1302/2058-5241.6.210064

Intramuscular desmoplastic fibroblastoma: a case report of extreme rarities in extremities

Soft tissue tumors are part of a wide and sometimes rare differential diagnostic landscape. Case description of these rare soft tissue masses helps the future differentiation and aids in preoperative multidisciplinary approach. Interpretation and staging, with the help of imaging, is key.

Bilateral Post Traumatic Myositis Ossificans of Adductor Longus in a Young Soccer Player: A Case Report and Literature Review

ABSTRACT

Myositis ossificans traumatica (MOT) is a self-limiting and self-resolving pathology. In most cases, conservative treatment is chosen as the first step. Surgical treatment is reserved for cases of failure of conservative treatment with persistence of pain and mass. The case presented concerns an 18-year-old soccer player suffering from bilateral adductor longus (AL) MOT results following two different sports injuries. The patient reports the appearance of swelling and palpable mass at the proximal and medial region of the thigh, about 2 cm from the pubic symphysis, along the course of the adductor magnus. The radiological investigation showed the presence of a calcification along the course of the right and left AL muscles. Surgical treatment was considered for the right thigh injury, being symptomatic 1 year after the onset and refractory to other treatments. At 3 months of follow-up, the patient was asymptomatic and completed the rehabilitation program for the recovery of muscle strength and range of motion (ROM). In cases where MOT manifests with resistant pain, ROM restriction and daily activity reduction, surgical excision is the preferred option.

Zygomaticocoronoid ankylosis with possible myositis ossificans: a very rare case

Ankylosis forming between the zygomatic arch and the coronoid process is a rarely encountered pathological extracapsular ankylosis. Its treatment protocol consists of surgical removal of the coronoid process with the ankylotic mass and jaw opening-closing exercises after surgery. Myositis ossificans (MO) is a self-limiting, benign ossifying lesion. It affects all types of soft tissues including subcutaneous adipose tissue, muscles, tendons and nerves. It is most frequently found in the muscle as a solitary lesion. The clinical appearance of MO is generally in the form of a mass characterized with an ossified soft tissue. When it develops alone, cross-sectional imaging might not be specific, and it may appear similar to worse etiologies. It is suggested multiple imaging modalities should be used in the assessment of a suspicious soft tissue mass. MO is a benign self-limiting disease. In this case report, in the radiographic examination of a 41-year-old female patient, ankylosis between the left coronoid process and the zygomatic bone accompanied by possible MO in the left medial pterygoid muscle was observed. Resection of the coronoid process with the ipsilateral route, resection of the ankylotic mass with the hemicoronal approach and resection of the contralateral coronoid process with the intraoral approach were performed, but the ossified formation in the medial pterygoid muscle was not touched.

Are open surgery and total resection good choices for traumatic myositis ossificans in children?

BACKGROUND

Traumatic myositis ossificans is a self-limited, non-neoplastic, ectopic bone formation in the soft tissues caused by trauma. Conservative treatment is the mainstay of management. However, open surgery and complete resection should be considered in patients with limited joint function and constant pain. Herein, we retrospectively analyzed the outcome of open surgical resection in children with myositis ossificans (MO).

METHODS

The data of patients diagnosed with MO between February 2010 and May 2019 were retrospectively analyzed. The clinical data included medical history, physical examination, and laboratory, imaging, and pathological findings. All patients underwent an open surgery and total resection. Radiography findings and joint function were evaluated. Patients with developing complications, such as recurrence and assessing joint function, were followed up. In total, 20 patients (sex, 15 male and 5 female patients; age, 8.1 ± 2.5 years) were included.

RESULTS

MO was located around the elbow, wrist, proximal humerus, and thigh in 13, one, one, and five patients, respectively. All patients were followed up for > 12 months. Two patients had partial recurrence after surgery. One patient with forearm MO had poor elbow function (Broberg-Morrey score of 70). Nineteen patients had good functional outcomes according to the Broberg-Morrey and Cooney methods.

CONCLUSION

Open surgical resection is an effective method for children with MO. The recurrence rate was low when the surgery was performed after the acute stage (1.5 months from disease presentation).

Non-traumatic myositis ossificans

Myositis ossificans (MO) is a benign, ossifying lesion that usually affects the skeletal muscle. The rare non-traumatic form of MO can cause diagnostic dilemma and management issues. These lesions, however, have similar radiology and histopathological characteristics described in the more frequently encountered traumatic forms. Depending on the stage of the lesion, the inherent feature of myositis ossificans varies, and so does the management of the lesion. We describe a non-traumatic MO occurring in latissimus dorsi of a young girl and discuss the review of literature on this rare subtype.

Post-traumatic myositis ossificans: a benign lesion that simulates malignant bone and soft tissue tumours

Myositis ossificans (MO) is a benign bone formation in an extra-skeletal location. The most common subtype of MO, the post-traumatic, usually develops in young males after a traumatic event or sports injury.MO may simulate malignant bone lesions such as extra-skeletal or surface osteosarcomas, or soft tissue sarcomas such as synovial sarcoma or undifferentiated pleomorphic sarcoma. In the early phase the diagnosis of MO is challenging because imaging and histopathological findings may be non-characteristic.Detailed medical history as well as clinical examination, follow-up imaging studies and histological assessment are crucial for a proper diagnosis. Early and accurate differential diagnosis between MO and malignant soft tissue and bone tumours is important to maximize. Cite this article: EFORT Open Rev 2021;6:572-583. DOI: 10.1302/2058-5241.6.210002.

Myositis ossificans of the hip joint causing sciatic nerve palsy following Guillain-barré syndrome: A case report

INTRODUCTION AND IMPORTANCE

Myositis ossificans of the hip is a rare entity caused by trauma and neurological conditions which lead to lamellar bone formation around the joint.

CASE PRESENTATION

We present a 47 years old patient with myositis ossificans of the left and the piriformis muscle following Guillain Barré syndrome causing sciatic nerve palsy (Piriformis syndrome).

CLINICAL DISCUSSION

Clinical assessment revealed global limitation of the left hip movements and palpable bony mass on the lateral aspect of the left hip. Radiographs and computed tomography showed extensive myositis ossificans of the left hip and non-bridging calcification noted on the asymptomatic right side. During initial medical management and physiotherapy patient developed sciatic nerve palsy due to piriformis syndrome and ankylosis of the hip on the left side. Surgical exploration of the sciatic nerve and debridement of the hip. The left hip was found ankylosed and not salvageable. Uncemented total hip arthroplasty was carried out in the session. The patient recovered completely from sciatic nerve palsy and regained the range of motion of the hip. He is under follow-up for the recurrence of myositis ossificans.

CONCLUSION

Guillain-barré syndrome causing piriformis syndrome is a rare entity. Extensive myositis ossificans causing sciatic nerve palsy is even rarer. An awareness of this entity, early detection, and intervention of this condition may help to preserve the native hip.

Imaging review of normal anatomy and pathological conditions involving the popliteus

Popliteus is an integral component of the posterolateral corner of the knee. We review the anatomy and various pathologies affecting the popliteus.

Endoscopic Treatment of Calcific Tendinitis of the Gluteus Maximus: A Case Report

CASE

Calcific tendinitis of the gluteus maximus is a rare condition with poorly described operative treatment options. We present a 51-year-old man with chronic left posterolateral hip pain because of gluteus maximus calcific tendinitis that was refractory to conservative treatment. Endoscopy was pursued given the severity and chronicity of his symptoms. The patient remains asymptomatic without recurrence.

CONCLUSION

This is the first description of endoscopic management of calcific tendinitis of the gluteus maximus. This is a minimally invasive, efficacious option for management of this pathology.

Myositis ossificans causing ulnar neuropathy: a case report

Myositis ossificans (MO) can compress peripheral nerves and cause neuropathy. We herein describe a patient with ulnar neuropathy caused by MO at the medial elbow. A 28-year-old man with a drowsy mentality and multiple organ damage following a traffic accident was admitted to our hospital. After 3 weeks of postoperative care, the patient’s mental status recovered. However, he complained of severe sharp pain in his left medial forearm and fourth and fifth fingers. He exhibited weak fifth finger abduction and wrist adduction. Severe elbow joint pain was elicited during range-of-motion testing of his left elbow. Ultrasound also showed an edematous, enlarged, hypoechoic ulnar nerve lying above the MO, and the MO outwardly displaced the ulnar nerve. Elbow radiographic examination, computed tomography, and magnetic resonance imaging revealed MO development and compression of the left ulnar nerve. The patient underwent surgery; the following day, his left medial forearm pain completely disappeared with slight improvement in the motor weakness of fifth finger abduction. Ultrasound is a useful tool to easily evaluate the presence of MO and compression of peripheral nerves caused by MO.