Melorheostosis: a Rare Sclerosing Bone Dysplasia

A focus on melorheostosis disease: a literature review and case report of femoral-acetabular impingement due to melorheostosis treated with surgical hip osteoplasty

OBJECTIVE

Melorheostosis is a rare, non-hereditary, benign bone disease characterized by abnormal bone growth. Generally, melorheostosis develops during childhood or adolescence and progresses gradually over time. This disease represents a true challenge to the physician because of its variability due to location, extension of the affected bone, and involvement of associated soft tissue. Pain management, physical therapy, and surgery may be recommended, depending on the individual case. This review aims to get an overview of the latest evidence relating to epidemiology, clinical and radiographic characteristics, diagnosis, and possible therapeutic strategies for melorheostosis and describe our experience through a clinical case.

METHODS

We designed a comprehensive literature search on melorheostosis in MEDLINE (via Pubmed) up to April 2023 and reviewed reports published in international journals.

RESULTS

The purpose is to highlight the importance of a multidisciplinary approach in the management of a rare disease such as melorheostosis. We discuss the role of different physicians, including genetists, rheumatologists, physiatrists, physical therapists, and orthopedic surgeons, in providing accurate diagnoses and effective treatments. We conducted a comprehensive review of the literature on the treatment of melorheostosis to support these findings. In addition, the article presents a case study of a patient suffering from melorheostosis, focusing on difficulties in reaching a correct diagnosis and attempts towards conservative and surgical interventions. The patient underwent hip arthroplasty, and the final result was an improvement in function and a reduction in pain.

CONCLUSIONS

Managing melorheostosis can be challenging, and there is no standardized treatment for this condition at the moment.

Bone Material Properties in Bone Diseases Affecting Children

PURPOSE OF REVIEW

Metabolic and genetic bone disorders affect not only bone mass but often also the bone material, including degree of mineralization, matrix organization, and lacunar porosity. The quality of juvenile bone is moreover highly influenced by skeletal growth. This review aims to provide a compact summary of the present knowledge on the complex interplay between bone modeling and remodeling during skeletal growth and to alert the reader to the complexity of bone tissue characteristics in children with bone disorders.

RECENT FINDINGS

We describe cellular events together with the characteristics of the different tissues and organic matrix organization (cartilage, woven and lamellar bone) occurring during linear growth. Subsequently, we present typical alterations thereof in disorders leading to over-mineralized bone matrix compared to those associated with low or normal mineral content based on bone biopsy studies. Growth spurts or growth retardation might amplify or mask disease-related alterations in bone material, which makes the interpretation of bone tissue findings in children complex and challenging.

Spinal Melorheostosis: A Rare Presentation

CASE

A 22-year-old female patient was referred to the orthopaedic department for further examination after a radiopaque area was observed in the T6 vertebra in her chest radiograph. Computed Tomography (CT) showed a sclerotic mass with smooth borders, involving the entire body of the T6 vertebra, left posterior elements, posterior of the rib past the left zygapophyseal joint, and a "flowing candle wax" image toward the T7 vertebra. Spinal melorheostosis was considered radiologically in the patient, but malignancy could not be completely excluded. Thereupon, open biopsy was performed under general anesthesia.

CONCLUSION

Spinal melorheostosis is a rare condition. Histological examination should be considered in cases where the diagnosis remains suspicious after clinical and radiological evaluations.

Occupational engagement, fatigue, and upper and lower extremity abilities in persons with melorheostosis

INTRODUCTION

Melorheostosis is a rare bone disorder with limited literature that describes the effect of this disease on functional and motor abilities. As part of a natural history study, four outcome measures were administered to better understand the burden this disease has on a person's ability to engage in basic and instrumental activities of daily living.

OBJECTIVE

To investigate the relationship between functional engagement, fatigue, and motor ability in patients with melorheostosis.

DESIGN

Cross-sectional data gathered from a longitudinal natural history observational study.

SETTING

Rehabilitation department within a single institution.

PARTICIPANTS

Forty-seven adult volunteers with melorheostosis were enrolled. Two participants were removed for failure to meet diagnosis eligibility. Thirty patients had lower extremity (LE) osteosclerotic bone lesions, 14 had upper extremity (UE) lesions, and one had lesions in both UEs and LEs.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Activity Card Sort, Second Edition (ACS); Multi-Dimensional Fatigue Inventory; Lower Extremity Functional Scale; Upper Extremity Functional Index.

RESULTS

On the ACS, high-demand leisure (HDL) activities were the least retained (p < .001). Of the activities rated most important, HDL activities were the most likely to have been given up (27%). General fatigue (μ = 11.8) and physical fatigue (μ = 11.0) were the two most limiting fatigue constructs. There were moderate negative correlations with HDL activities compared to physical fatigue (r = -0.524, p < .001) and reduced activity fatigue (r = -0.58, p = .001). LE lesions had a large effect on completing LE tasks (d = 0.95) and UE lesions had a medium effect on completing tasks involving the UE (d = 0.69).

CONCLUSIONS

Patients with melorheostosis experience fatigue and low engagement in HDL activities. The results of this study underscore the importance of acknowledging activity domain, fatigue constructs, and lesion location to support and provide targeted evidence-based rehabilitative therapy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02504879.

Melorheostosis: A Review of the Literature and a Case Report

Background and Objectives: Melorheostosis, also referred to in the literature as Leri's disease, is an unusual mesenchymal dysplasia with the clinical appearance of benign sclerosing bone dysplasia; it frequently occurs in late adolescence. Any bone in the skeletal system can be affected by this disease, though the long bones of the lower extremities are the most common, at any age. Melorheostosis has a chronic evolution, and symptoms are usually absent in the early stages. The etiopathogenesis is still unknown, however, numerous theories have been proposed that could explain the appearance of this lesion formation. An association with other benign or malignant bone lesions is also possible, and associations with osteosarcoma, malignant fibrous histiocytoma, or Buschke-Ollendorff syndrome have also been reported. There have also been reported cases of the malignant transformation of a pre-existing melorheostosis lesion into malignant fibrous histiocytoma or osteosarcoma. The diagnosis of melorheostosis can be made only based on radiological images, but, due to its polymorphism, additional imaging investigations are often necessary and sometimes only a biopsy can establish a definite diagnosis. Because there are currently no guidelines for treatment based on scientific evidence, due to the low number of cases diagnosed worldwide, our objective was to highlight the early recognition and specific surgical treatments for better prognosis and outcomes. Materials and Methods: We conducted a review of the literature consisting of original papers, case reports, and case series and presented the clinical and paraclinical characteristics of melorheostosis. We aimed to synthesize the treatment methods available in the literature as well as determine possible future directions related to the treatment of melorheostosis. Furthermore, we presented the results of a case of femoral melorheostosis admitted to the orthopedics department of the University Emergency Hospital of Bucharest in a 46-year-old female patient with severe pain in the left thigh and limitation of joint mobility. Following the clinical examination, the patient complained of pain in the middle third of the left thigh in the antero-medial compartment; the pain appeared spontaneously and was aggravated during physical activity. The pain started about two years prior, but the patient experienced complete pain relief after the administration of non-steroidal anti-inflammatory drugs. In the last six months, the patient presented an increase in pain intensity without significant improvement following the administration of non-steroidal anti-inflammatory drugs. The patient's symptoms were mainly determined by the increase in the volume of the tumor and the mass effect on the adjacent tissues, especially on the vessels and the femoral nerve. The CT examination and bone scintigraphy showed a unique lesion in the middle third of the left femur and no oncological changes in the thoracic, abdominal, and pelvic regions; however, at the level of the femoral shaft, there was a localized cortical and pericortical bone lesion formation that surrounded approximately 180 degrees of the femoral shaft (anterior, medial, and lateral). It had a predominantly sclerotic structure but was associated with lytic areas with thickening of the bone cortex and areas of periosteal reaction. The next therapeutic gesture was to perform an incisional biopsy using a lateral approach at the level of the thigh. The histopathological result supported the diagnosis of melorheostosis. Additionally, immunohistochemical tests completed the data obtained after the microscopic examination through the classic histopathological technique The patient was discharged and included in a full medical recovery program for eight weeks in a specialized medical center, during which she also received analgesic treatment in maximum doses, but without improvement regarding her symptoms. Taking into account the chronic evolution of the pain, the complete lack of response to conservative treatment after eight weeks, and the lack of treatment guidelines in the case of melorheostosis, a surgical approach needed to be considered. The surgical option in this case, considering the circumferential location of the lesion at the level of the femoral diaphysis, was a radical resection. The surgical approach consisted of segmental resection to healthy bone tissue and reconstruction of the remaining defect with a modular tumoral prosthesis. At the 45-day postoperative control, the patient no longer complained of pain in the operated-on limb and was mobile with full support without gait difficulties. The follow-up period was one year, and the patient presented complete pain relief and a very good functional outcome. Results: In the case of asymptomatic patients, conservative treatment seems to be a good option with optimal results. However, for benign tumors, it remains unclear whether radical surgery is a viable option. Conclusions: Melorheostosis remains an incompletely understood disease, given the limited number of cases worldwide, and thus, there is a lack of clinical guidelines regarding specialized treatment.

Buschke-Ollendorff Syndrome: A Rare Cause of Unilateral Genu Valgum

Buschke-Ollendorff syndrome is a rare, often benign, autosomal dominant skin disorder. This syndrome commonly presents with non-tender connective tissue nevi and sclerotic bony lesions. Characteristic skeletal findings such as melorheostosis and hyperostosis are usually present. Most cases are detected incidentally. Skin lesions appear first and become less noticeable with age. Bone lesions occur in the later decades of life. Another rarely associated symptom, melorheostosis, is manifested by the appearance of wax running through the cortex of the bone. Plain radiographs usually show cortical hyperostosis. This study aims to present a case report of Buschke-Ollendorff syndrome from an orthopedic aspect and emphasize the importance of the disease since it can be easily assessed as a bone tumor. Second, to the best of our knowledge, this is the first case presented with a unilateral genu valgum deformity with a long-term follow-up in the relevant literature.

Late-Onset Melorheostosis: A Case Report

Melorheostosis is a rare benign bone pathology involving bone dysplasia and hyperostosis. The disease can be recognized with a characteristic radiographic feature of radiopaque lesions dripping along a long bone's diaphysis. The aberrant bone formation and development manifests mainly as pain, edema, and paresthesia of the affected limb. Severe cases may report limb deformity as well as limited range of motion. Until now, there have been approximately 300 cases reported about melorheostosis worldwide and its diverse clinical picture and age distribution. In Vietnam, there is only one known case of melorheostosis discovered incidentally via radiography. The scarcity of cases presents a challenge within the medical community in recognizing and diagnosing the condition, and a delayed diagnosis can lead to severe contracture and compromised limb motility. In this article, we reported an 82-year-old case of polyostotic melorheostosis with late onset and predominant edema, affecting the sternum, the ribs, and multiple bones of the right extremities and presented our clinical approach for a geriatric patient with chronic limb edema. Our case is distinctive in terms of anatomical location as well as the predominant 20-year non-pitting edema. A prompt diagnosis was made upon the classic dripping candle wax radiographic features emphasizing the role of plain X-ray in establishing the diagnosis without extraneous utilization of other modalities and invasive procedures. Exclusion of other causes of chronic edema such as lymphadenopathy, malignancy as well as parasitic infection is of clinical importance.

Hereditary Metabolic Bone Diseases: A Review of Pathogenesis, Diagnosis and Management

Hereditary metabolic bone diseases are characterized by genetic abnormalities in skeletal homeostasis and encompass one of the most diverse groups among rare diseases. In this review, we examine 25 selected hereditary metabolic bone diseases and recognized genetic variations of 78 genes that represent each of the three groups, including sclerosing bone disorders, disorders of defective bone mineralization and disorder of bone matrix and cartilage formation. We also review pathophysiology, manifestation and treatment for each disease. Advances in molecular genetics and basic sciences has led to accurate genetic diagnosis and novel effective therapeutic strategies for some diseases. For other diseases, the genetic basis and pathophysiology remain unclear. Further researches are therefore crucial to innovate ways to overcome diagnostic challenges and develop effective treatment options for these orphan diseases.

Atypical presentation of melorheostosis with soft tissues involvement: a case report

Background

Melorheostosis is a skeletal disorder giving rise to a dripping wax appearance. The exact cause is still unclear, and the diagnosis is always challenging due to its wide differential diagnoses. Soft tissue involvement of melorheostosis has been reported in previous literatures but it is a rare phenomenon.

Case presentation

A 10-year-old child with melorheostosis presented with hematuria. Ultrasonography (USG) identified a cystic lesion in the right hemipelvis adjacent to the urinary bladder which was initially regarded as an ovarian cyst. Computed tomography (CT) confirmed the cystic lesion as a fusiform right internal iliac artery aneurysm, as well as multiple right retroperitoneal and right lower limb capillary hemangiomas with uterine involvement. Hence, the final diagnosis was atypical melorheostosis with vascular malformations. The patient was managed conservatively with Sirolimus therapy for the vascular anomalies.

Conclusion

Albeit the rare involvement of soft tissues, careful search for vascular malformation is recommended in melorheostosis.

Clinical and Histopathological Features of Scleroderma-like Disorders: An Update

Scleroderma-like disorders include a set of entities involving cutis, subcutis and, sometimes, even muscular tissue, caused by several pathogenetic mechanisms responsible for different clinical–pathological pictures. The absence of antinuclear antibodies (ANA), Raynaud’s phenomenon and capillaroscopic anomalies constitutes an important element of differential diagnosis with systemic sclerosis. When scleroderma can be excluded, on the basis of the main body sites, clinical evolution, any associated pathological conditions and specific histological features, it is possible to make a correct diagnosis.

Spotted bones in an osteopoikilosis-related disease (Buschke Ollendorff Syndrome): Identifying this rare condition from the lab to the field

OBJECTIVE

To improve the differential diagnosis of osteopoikilosis in past populations using a clinical case as an example of this rare condition.

MATERIALS

A patient referred to our Genetic Service with suspected Buschke Ollendorff Syndrome after finding a connective nevus.

METHODS

Radiological images from different body regions were accompanied by a genetic study using next-generation sequencing.

RESULTS

Small circular-to-ellipsoid sclerotic lesions were found in the epiphysis and metaphysis of long bones, as well as in the pelvis. These lesions were bilaterally distributed and with well-defined margins, compatible with the characteristics of Buschke Ollendorff Syndrome, bone manifestation osteopoikilosis. A heterozygous mutation on LEMD3 (NM_001167614:c.1918 + 1G > C) was identified by next-generation sequencing. Based on this confirmed case, we have discussed the most probable causes of similar bone lesions found in the archaeological record.

CONCLUSION

It has been demonstrated how a current case of a rare disease can provide useful tools to improve the differential diagnosis of this disease in ancient skeletons.

SIGNIFICANCE

This work underlines the great need for multidisciplinary platforms that integrates clinical research into paleopathology in order to successfully address the study of rare diseases from the past.

LIMITATIONS

Since OPK is only detected by X-rays, suspected cases of this bone lesion will only be identified when radiographs are taken for other purposes.

SUGGESTIONS FOR FURTHER RESEARCH

Retrospective and large-scale studies of radiographs from other research in past populations.

Bisphosphonate Therapy in the Management of Symptomatic Melorheostosis of Tibia

INTRODUCTION

Melorheostosis is a rare sclerosing bone disease characterized by linear hyperostotic bone dysplasia with its radiological appearance as melting candle wax dripping by its side. It usually affects long bones, especially the lower limb. The exact cause of the disease has not been clearly explained though many theories are available. It is insidious in onset and symptoms being pain, deformity, and joint stiffness. Although there is no definitive treatment, the administration of bisphosphonates dramatically reduces pain and improves the patient clinically.

CASE REPORT

We described a case of a 28-year-old female who presented with a history of pain and swelling in her left leg for the past 2 years. The onset of complaints was insidious. On physical examination, there was tender swelling over the shaft of the tibia with irregular borders. Knee and ankle range of movements were normal. Radiographs showed hyperostosis of the proximal two-thirds of the tibia of the left leg with a flowing candle wax appearance. The patient was treated with a single dose of intravenous zolendronic acid and physical therapy. The patient had dramatic alleviation of pain without the need for any further treatment till 1 year follow-up.

CONCLUSION

Although there is no specific treatment available for this disease, the intravenous infusion of zolendronic acid has dramatically improved the patient clinically.

Osteoblast Dysfunction in Non-Hereditary Sclerosing Bone Diseases

A review of the available literature was performed in order to summarize the existing evidence between osteoblast dysfunction and clinical features in non-hereditary sclerosing bone diseases. It has been known that proliferation and migration of osteoblasts are concerted by soluble factors such as fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor (TGF), bone morphogenetic protein (BMP) but also by signal transduction cascades such as Wnt signaling pathway. Protein kinases play also a leading role in triggering the activation of osteoblasts in this group of diseases. Post-zygotic changes in mitogen-activated protein kinase (MAPK) have been shown to be associated with sporadic cases of Melorheostosis. Serum levels of FGF and PDGF have been shown to be increased in myelofibrosis, although studies focusing on Sphingosine-1-phosphate receptor was shown to be strongly expressed in Paget disease of the bone, which may partially explain the osteoblastic hyperactivity during this condition. Pathophysiological mechanisms of osteoblasts in osteoblastic metastases have been studied much more thoroughly than in rare sclerosing syndromes: striking cellular mechanisms such as osteomimicry or complex intercellular signaling alterations have been described. Further research is needed to describe pathological mechanisms by which rare sclerosing non hereditary diseases lead to osteoblast dysfunction.

The combined prevalence of classified rare rheumatic diseases is almost double that of ankylosing spondylitis

BACKGROUND

Rare diseases (RDs) affect less than 5/10,000 people in Europe and fewer than 200,000 individuals in the United States. In rheumatology, RDs are heterogeneous and lack systemic classification. Clinical courses involve a variety of diverse symptoms, and patients may be misdiagnosed and not receive appropriate treatment. The objective of this study was to identify and classify some of the most important RDs in rheumatology. We also attempted to determine their combined prevalence to more precisely define this area of rheumatology and increase awareness of RDs in healthcare systems. We conducted a comprehensive literature search and analyzed each disease for the specified criteria, such as clinical symptoms, treatment regimens, prognoses, and point prevalences. If no epidemiological data were available, we estimated the prevalence as 1/1,000,000. The total point prevalence for all RDs in rheumatology was estimated as the sum of the individually determined prevalences.

RESULTS

A total of 76 syndromes and diseases were identified, including vasculitis/vasculopathy (n = 15), arthritis/arthropathy (n = 11), autoinflammatory syndromes (n = 11), myositis (n = 9), bone disorders (n = 11), connective tissue diseases (n = 8), overgrowth syndromes (n = 3), and others (n = 8). Out of the 76 diseases, 61 (80%) are classified as chronic, with a remitting-relapsing course in 27 cases (35%) upon adequate treatment. Another 34 (45%) diseases were predominantly progressive and difficult to control. Corticosteroids are a therapeutic option in 49 (64%) syndromes. Mortality is variable and could not be determined precisely. Epidemiological studies and prevalence data were available for 33 syndromes and diseases. For an additional eight diseases, only incidence data were accessible. The summed prevalence of all RDs was 28.8/10,000.

CONCLUSIONS

RDs in rheumatology are frequently chronic, progressive, and present variable symptoms. Treatment options are often restricted to corticosteroids, presumably because of the scarcity of randomized controlled trials. The estimated combined prevalence is significant and almost double that of ankylosing spondylitis (18/10,000). Thus, healthcare systems should assign RDs similar importance as any other common disease in rheumatology.

Meralgia Paresthetica Caused by Melorheostosis Affecting the Ipsilateral Ilium: A Case Report

CASE

A 51-year-old woman presented with a 2-month history of pain in the right thigh. Radiography and computed tomography of the pelvis showed cortical hyperostosis of the right ilium. She was diagnosed with meralgia paresthetica (MP) caused by melorheostosis involving the right ilium. After 6 weeks of conservative management, an operation was performed for the persisting pain. At the 1-year follow-up, no findings of recurrence were observed clinically and radiographically.

CONCLUSION

MP, caused by proximal irritation of the lateral femoral cutaneous nerve, can occur because of melorheostosis, which is a rare condition.

A systematic review of the clinical and radiographic features of hybrid central giant cell granuloma lesions of the jaws

OBJECTIVE

Central giant cell granuloma (CGCG) can coexist with other benign lesions of the jaw. These hybrid lesions are diagnostically challenging to both oral pathologists and radiologists. This work systematically reviews the clinical and radiographic features of hybrid-CGCG lesions in the jaws.

MATERIALS AND METHODS

Three reviewers conducted an electronic search of five databases for histologically diagnosed hybrid-CGCG lesions in human jaws.

RESULTS

Thirty-four of 1224 articles met the inclusion criteria. Of 39 hybrid-CGCG lesions, 14 (35.9%) were central odontogenic fibroma, 11 (28.2%) were central ossifying fibroma, seven (17.9%) were fibrous dysplasia, and seven (17.9%) were other bone conditions. There were 22 females and 17 males with a mean age of 30.5 ± 19.9 years. 89.5% of hybrid-CGCG lesions were well defined, 57.9% were non-corticated, 60.5% were radiolucent, and 66.7% were in the posterior mandible. Most hybrid lesions affected the cortical plates by thinning, expansion, or perforation (93.1%), displaced, or resorbed teeth (60%).

CONCLUSION

The radiographic features of hybrid-CGCG lesions vary according to the concurrent bony lesion. Hybrid-CGCG lesions altered the radiographic appearance with the following entities: fibrous dysplasia, melorheostosis, and Paget's disease. Optimal imaging modalities are crucial to detail radiographic features and direct representative biopsy of suspicious sites that may host a CGCG hybridisation.

Cross-Sectional Imaging Useful in Melorheostosis

Melorheostosis is a rare disease of bone overgrowth that is primarily diagnosed based on imaging studies. Recently, the association of different radiological patterns of the disease with distinct genetic cause was reported. Several case reports have described the radiological findings in patients with melorheostosis. However, the added value of cross‐sectional imaging with CT and MRI beyond X‐rays has not been investigated. The aim of the current study was to investigate this existing gap in knowledge. Forty patients with melorheostosis seen at the National Institute of Health Clinical Center were included in the study, and all their imaging studies were analyzed. The sequence of interpretation was X‐ray followed by CT and then MRI. CT images were extracted from whole‐body 18F‐sodium fluoride positron emission tomography/CT studies. The information from CT reclassified the initial X‐rays based radiological pattern in 13 patients. Additionally, CT comprehensively identified joint involvement and disease extent. In 76% of patients (n = 29) who underwent MRI, additional findings were noted, ranging from soft tissue edema to identification of soft tissue masses and incidental findings. MRI did not provide additional information on skeletal lesions beyond CT scans. However, it revealed the extension of soft tissue ossification into ischiofemoral space in four patients who complained of deep gluteal pain consistent with ischiofemoral impingement syndrome. In addition, MRI revealed soft tissue edema in 20 patients, 9 of whom had bone marrow edema and periosteal edema in the tibias consistent with shin splints. These findings suggest that select patients with melorheostosis should be evaluated with both CT and MRI, particularly patients in whom the distribution of pain does not correlate with the anatomic location of the disease in plain radiographs. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Osteoblastic and hyperostotic craniofacial lesion detected by 99mTc-labeled methylene diphosphonate bone scintigraphy and single-photon emission computed tomography/computed tomography: a pictorial essay

99mTc-bisphophonates bone scan, planar and single-photon emission computed tomography/computed tomography (SPECT/CT) modalities, is a commonly used technique that provides high sensitivity and specificity for detection of osseous metastases. However, besides bone metastases, SPECT/CT provides an accurate evaluation of the localization of the lesions and supplies anatomic information that can be valuable for diagnosis of nonmalignant bone diseases, occasionally disclosed in the skull. Reporting of craniofacial lesions detected by 99mTc-MDP (99mTc-labeled methylene diphosphonate) bone scintigraphy and SPECT/CT in the literature is limited. The aim of this pictorial review is to present the findings detected by 99mTc-MDP bone scintigraphy and SPECT/CT including cases under two broad categories: osteoblastic and hyperostosis craniofacial lesions.

Axial melorheostosis: A rare presentation

Melorheostosis is a rare sclerosing bone dysplasia that most commonly affects the lower extremity long bones in a sclerotomal distribution. Melorheostosis of the spine is a particularly rare manifestation of this disease. In the appendicular skeleton, melorheostosis has a pathognomonic imaging appearance of flowing hyperostosis resembling melted candle wax flowing down the margins of a candlestick. In the spine, it can have a variety of imaging manifestations from unilateral focal sclerotic lesions resembling enostoses, to more bulky and deformative hyperostosis that span and fuse multiple adjacent spinal segments. This combination of nonaggressive radiologic features makes melorheostosis a particularly important diagnosis for radiologists to understand so that they may spare their patients unnecessary biopsy. Here we present the clinical features and computed tomography findings in a 33-year-old male with spinal melorheostosis involving the first and second cervical vertebrae.

Bone Features of Unaffected Skeletal Sites in Melorheostosis: A Case Report

BACKGROUND

Melorheostosis is a rare sporadic sclerosing bone dysplasia, which commonly affects appendicular skeleton with bone hyperostosis and soft tissues sclerosis; fragility fractures are rare in melorheostotic patients. We investigated bone features at unaffected sites in a postmenopausal woman with melorheostosis of the right lower limb and with a fracture of the melorheostosis-free T11 vertebral.

METHODOLOGY

Melorheostotic lesions were evaluated by plain radiography, magnetic resonance of the right lower limb, and whole-body bone scintigraphy. Dual X-ray absorptiometry, trabecular bone score, and quantitative computed tomography were performed to investigate unaffected bone sites. Biochemical assessment of bone metabolism was obtained.

RESULTS

Dual X-ray absorptiometry was indicative of normal mineralization at femoral sites and osteopenia at lumbar spine (T-score -1.1), which was confirmed by spinal quantitative computed tomography (volumetric bone mineral density 89 mg/cm³). Trabecular bone score suggested only mildly altered bone microarchitecture (1.304, normal values >1.350). Bone markers were consistent with high bone turnover. Causes of secondary osteoporosis or alterations in bone metabolism were excluded. Zoledronic acid induced a reduction in bone turnover markers after 6 months without significant changes in clinical features.

CONCLUSIONS

Fragility fractures at apparently unaffected sites may occur in adults with melorheostosis, in absence of significant demineralization diagnosed by dual X-ray absorptiometry, trabecular bone score, and quantitative computed tomography, which may underestimate the fracture risk in this set of patients. Treatment with zoledronate could be considered also to prevent fragility fractures.

The dripping candle wax sign of melorheostosis

Melorheostosis is a rare benign bone disease including dysostosis and sclerosis. Dripping candle wax presence is a common and typical sign of melorheostosis. This sign appears as irregular hyperostosis of the cortical bone which is likened to melted wax flowing down one side of a candle. It can sometimes cause pain, stiffness joint, or limitation of motion in the affected areas implicitly but mostly has no symptoms. It is usually observed on plain radiography; its appearance is generally hyperplasia on one side of the bone. We report a 33-year-old male who has an incidental diagnosis of melorheostosis post-trauma.

Melorheostosis: A Clinical, Pathologic, and Radiologic Case Series

Melorheostosis is a rare sclerosing bone disease characterized by excessive cortical bone deposition that is frequently on the differential diagnosis for bone biopsies. Although the radiologic pattern of "dripping candle wax" is well known, the pathologic findings have been poorly defined. Here, we comprehensively describe the histology of melorheostosis in 15 patients who underwent bone biopsies. Common histologic findings included: dense cortical bone (73.3%), woven bone (60%), and hypervascular features and increased porosity (66.7%). One third of the patients (5/15) also had prominent cement lines. Multiple patients had >1 histologic pattern (ie, dense cortical bone and hypervascularity). Overall, this study suggests that melorheostosis exists with several histologically distinct patterns. When confronted with a case of suspected melorheostosis, the clinical pathologist should use the histologic features common to melorheostotic lesions presented here in conjunction with the patient's clinical presentation and radiographic findings to arrive at a diagnosis. An illustrative case is presented.

Melorheostosis and Osteopoikilosis Clinical and Molecular Description of an Italian Case Series

Melorheostosis (MEL) is an uncommon, sclerosing disease, characterised by hyperostosis of long bones, resembling the flowing of candle wax. The disease is sporadic and the pathogenesis is still poorly understood. Occasionally, the same family can include individuals with MEL and Osteopoikilosis (OPK), a disease characterised by multiple round foci of increased bone density. LEMD3 gene mutations are related to OPK and Buschke-Ollendorff Syndrome, a genetic condition in which an association between MEL, OPK and skin lesions is observed. In rare cases, LEMD3 mutations and recently mosaic MAP2K1 gene mutations have been correlated to MEL suggesting that somatic mosaicism could be causative of the disease. In this study, we described the clinical, radiological and molecular findings of 19 individuals with MEL and 8 with OPK and compared the results to the medical literature. The molecular analyses of this case series corroborate the available data in the medical literature, indicating that LEMD3 germline mutations are not a major cause of isolated MEL and reporting five further cases of OPK caused by LEMD3 germline mutations.

Osteoma-like melorheostosis: a rare type of skeletal dysplasia depicted on FDG PET/CT

Melorheostosis, also known as Leri's disease, is a rare benign form of mesodermal mixed sclerosing bone dysplasia. We report the unusual case of a 14-year-old boy with melorheostosis in the lower extremity that went undiagnosed due to concurrent Ewing sarcoma in the opposite limb, confounding the findings for metastatic disease. The diagnosis was made on FDG PET/CT when the patient presented for post Ewing sarcoma treatment follow-up. The different types of melorheostosis as well as the challenge of diagnosing this rare entity are discussed in this report.

Melorheostosis and Osteopoikilosis: A Review of Clinical Features and Pathogenesis

Melorheostosis is an exceptionally rare sclerosing hyperostosis that typically affects the appendicular skeleton in a limited segmental fashion. It occasionally occurs on a background of another benign generalised sclerosing bone condition, known as osteopoikilosis caused by germline mutations in LEMD3, encoding the inner nuclear membrane protein MAN1, which modulates TGFβ/bone morphogenetic protein signalling. Recent studies of melorheostosis lesional tissue indicate that most cases arise from somatic MAP2K1 mutations although a small number may arise from other genes in related pathways, such as KRAS. Those cases associated with MAP2K1 mutations are more likely to have the classic "dripping candle wax" appearance on radiographs. The relationship between these somatic mutations and those found in a variety of malignant conditions is discussed. There are also similar germline mutations involved in a group of genetic disorders known as the RASopathies (including Noonan syndrome, Costello syndrome and various cardiofaciocutaneous syndromes), successful treatments for which could be applied to melorheostosis. The diagnosis and management of melorheostosis are discussed; there are 4 distinct radiographic patterns of melorheostosis and substantial overlap with mixed sclerosing bone dysplasia. Medical treatments include bisphosphonates, but definitive guidance on their use is lacking given the small number of patients that have been studied. Surgical intervention may be required for those with large bone growths, nerve entrapments, joint impingement syndromes or major limb deformities. Bone regrowth is uncommon after surgery, but recurrent contractures represent a major issue in those with extensive associated soft tissue involvement.

Melorheostotic Bone Lesions Caused by Somatic Mutations in MAP2K1 Have Deteriorated Microarchitecture and Periosteal Reaction

Melorheostosis is a rare non-hereditary condition characterized by dense hyperostotic lesions with radiographic "dripping candle wax" appearance. Somatic activating mutations in MAP2K1 have recently been identified as a cause of melorheostosis. However, little is known about the development, composition, structure, and mechanical properties of the bone lesions. We performed a multi-method phenotype characterization of material properties in affected and unaffected bone biopsy samples from six melorheostosis patients with MAP2K1 mutations. On standard histology, lesions show a zone with intensively remodeled osteonal-like structure and prominent osteoid accumulation, covered by a shell formed through bone apposition, consisting of compact multi-layered lamellae oriented parallel to the periosteal surface and devoid of osteoid. Compared with unaffected bone, melorheostotic bone has lower average mineralization density measured by quantitative backscattered electron imaging (CaMean: -4.5%, p = 0.04). The lamellar portion of the lesion is even less mineralized, possibly because the newly deposited material has younger tissue age. Affected bone has higher porosity by micro-CT, due to increased tissue vascularity and elevated 2D-microporosity (osteocyte lacunar porosity: +39%, p = 0.01) determined on quantitative backscattered electron images. Furthermore, nano-indentation modulus characterizing material hardness and stiffness was strictly dependent on tissue mineralization (correlation with typical calcium concentration, CaPeak: r = 0.8984, p = 0.0150, and r = 0.9788, p = 0.0007, respectively) in both affected and unaffected bone, indicating that the surgical hardness of melorheostotic lesions results from their lamellar structure. The results suggest a model for pathophysiology of melorheostosis caused by somatic activating mutations in MAP2K1, in which the genetically induced gradual deterioration of bone microarchitecture triggers a periosteal reaction, similar to the process found to occur after bone infection or local trauma, and leads to an overall cortical outgrowth. The micromechanical properties of the lesions reflect their structural heterogeneity and correlate with local variations in mineral content, tissue age, and remodeling rates, in the same way as normal bone. © 2018 American Society for Bone and Mineral Research.

Melorheostosis with an associated para-articular enhancing soft tissue mass

Melorheostosis is a rare non-hereditary sclerosing bone dysplasia which predominantly affects the appendicular skeleton. Although melorheostosis is typically recognized as an osseous lesion, associated soft-tissue components have been reported. Advanced imaging with MRI may allow for more complete evaluation of these soft tissue components; however, there is little information regarding their MRI characteristics which may lead to confusion with malignant processes. We present a case of melorheostosis in a 32-year-old woman with an associated paraarticular enhancing soft tissue mass and emphasize discriminating this from soft tissue sarcoma.

Melorheostosis of The Leg: A Case Report

Melorheostosis is a benign hyperostotic disease of the peripheral skeleton, rarely involving the axial skeleton. This disease is associated with ossified and non-ossified soft tissue masses surrounding the joints. We report the case of a 28-year-old male who presented to an orthopedic clinic with a chronic history of right leg pain. Radiological evaluation using X-ray, computed tomography, and magnetic resonance imaging showed features consistent with that of melorheostosis. Recognition of this entity by clinicians can avoid unnecessary investigations and biopsy.

Debridement arthroplasty of a rare case of elbow stiffness. A case report and literature review

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Melorheostosis of the elbow associated with elbow stiffness is extremely rare.

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In the standard radiology or orthopedics literature Melorheostosis (from the Greek: melos = limb, rheos = flow) is described monotonously as a “flowing hyperostosis” resembling dripping candle wax.

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Patients with this condition may have joint pain, stiffness, deformity, and restricted range of motion due to bony and soft-tissue contracture. Involvement usually follows a sclerotomal distribution and usually affects only one extremity.

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There is no standard treatment for melorheostosis, and management plans must be made on an individual patient basis. The aims of treatment are pain relief and maintaining function.

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Some Surgical treatment for this condition includes tendon lengthening, excision of fibrous and osseous tissue, fasciotomy, capsulotomy, sympathectomy, corrective osteotomy, Ilizarov lengthening, arthrodesis, implant arthroplasty, and even amputation of severely affected limbs with vascular ischemia.

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In this study we found that debridement arthroplasty is safe and effective in treating elbow stiffness associated with Melorheostosis.

Introduction

Elbow stiffness is a common condition that affects the quality of life of patients. Melorheostosis of the elbow associated with elbow stiffness is extremely rare.

Presentation of case

We report the case of a 28 yr old male who presented with elbow stiffness which occurred within one year without prior history of trauma or infection. The patient had decrease in range of motion together with progressive worsening pain that forced him to seek medical attention.

Discussion

There is no standard treatment for melorheostosis, and management plans must be made on an individual patient basis. The aims of treatment are pain relief and maintaining function.

Conclusion

Debridement arthroplasty is safe and effective in treating elbow stiffness associated with Melorheostosis.

Sclerosing bone dysplasias

The group of sclerosing bone dysplasia's is a clinically and genetically heterogeneous group of rare bone disorders which, according to the latest Nosology and classification of genetic skeletal disorders (2015), can be subdivided in three subgroups; the neonatal osteosclerotic dysplasias, the osteopetroses and related disorders and the other sclerosing bone disorders. Here, we give an overview of the most important radiographic and clinical symptoms, the underlying genetic defect and potential treatment options of the different sclerosing dysplasias included in these subgroups.

Human Genetics of Sclerosing Bone Disorders

PURPOSE OF REVIEW

The group of sclerosing bone disorders encompasses a variety of disorders all marked by increased bone mass. In this review, we give an overview of the genetic causes of this heterogeneous group of disorders and briefly touch upon the value of these findings for the development of novel therapeutic agents.

RECENT FINDINGS

Advances in the next-generation sequencing technologies are accelerating the molecular dissection of the pathogenic mechanisms underlying skeletal dysplasias. Throughout the years, the genetic cause of these disorders has been extensively studied which resulted in the identification of a variety of disease-causing genes and pathways that are involved in bone formation by osteoblasts, bone resorption by osteoclasts, or both processes. Due to this rapidly increasing knowledge, the insights into the regulatory mechanisms of bone metabolism are continuously improving resulting in the identification of novel therapeutic targets for disorders with reduced bone mass and increased bone fragility.

Somatic activating mutations in MAP2K1 cause melorheostosis

Melorheostosis is a sporadic disease of uncertain etiology characterized by asymmetric bone overgrowth and functional impairment. Using whole exome sequencing, we identify somatic mosaic MAP2K1 mutations in affected, but not unaffected, bone of eight unrelated patients with melorheostosis. The activating mutations (Q56P, K57E and K57N) cluster tightly in the MEK1 negative regulatory domain. Affected bone displays a mosaic pattern of increased p-ERK1/2 in osteoblast immunohistochemistry. Osteoblasts cultured from affected bone comprise two populations with distinct p-ERK1/2 levels by flow cytometry, enhanced ERK1/2 activation, and increased cell proliferation. However, these MAP2K1 mutations inhibit BMP2-mediated osteoblast mineralization and differentiation in vitro, underlying the markedly increased osteoid detected in affected bone histology. Mosaicism is also detected in the skin overlying bone lesions in four of five patients tested. Our data show that the MAP2K1 oncogene is important in human bone formation and implicate MEK1 inhibition as a potential treatment avenue for melorheostosis.