MELORHEOSTOSISBy ansariHistory: 35year male with complains of pain and swelling in the left thigh with difficulty in walking. Findings: Discussion: Melorheostosis is a rare osteosclerotic bone dysplasia of unknown aetiology. Leri and Joanny reported it in 1922[1]. Leri s disease, hyperostose en coulee de bougie, osteosis eburnisans monomelia and osteopathia hyperostotica congenita membri unius are other synonyms [2]. Age of presentation varies widely, 50 % of the cases presenting in first two decades. There is no sex predilection. The condition is often incidentally detected. The disease usually is asymptomatic. This mesenchymal dysplasia is a developmental error at the site of both intramembranous and endochondral bone formation predominantly affecting the former. Pain, joint stiffness, deformity, contractures and muscle wasting may occur. The involved extremity may be shorter or less frequently longer than the uninvolved member [2][5]. Patients with Melorrheostosis may have associated cutaneous and soft tissue lesions such as vascular malformations, neurofibromas, hemangiomas, aneurysm, linear scleroderma, tuberous sclerosis and focal subcutaneous fibrosis. Melorheostosis has also been seen with osteopoikilosis, osteopathia striata and mixed sclerosing bone dystrophy [2] [5]. Laboratory results are normal. The clinical course is usually slowly progressive. Radiographic findings are often limited to a single limb (Monomelic). The lower extremity is more often affected than the upper extremity. The axial skeleton is less affected. The classic finding is that of undulating cortical hyperostosis in one bone (monostotic) or a series of bones (polyostotic) [2]. The appearance of osseous excrescence extending along the length of the bone simulates that of ‘wax flowing down the side of the lit candle’ [5]. The anomaly got its name from the Greek word for limb (Melos) and flow (rhein). The new bone formation mostly involves one side of cortex of a tubular bone with periosteal and endosteal involvement. Variable degree of intramedullay encroachment is present. Endosteal pattern marked by streakiness of the long bones and spotting of the small bones is characteristic of the childhood cases while in adults subperiosteal or extracortical pattern predominates. Lesions involving one or more sclerotomes are one of the distinguishing features of the disease [1]. A sclerotome is a zone of the skeleton supplied by an individual spinal sensory nerve. They hypothesized that a neural infection results in lesions distributed along tissues supplied by that nerve root. This may in part explain the monomelic tendency and linear track pattern of melorheostosis. CT scan and MRI can further characterize the lesions. CT scan will show clear demarcation between normal and abnormal bone [6]. CT scan is helpful to confirm or exclude continuity of osseous and soft tissue abnormalities [7]. MR imaging shows heterogeneous signal intensity due to mixture of osseous, fibrous, adipose and cartilaginous tissue which these lesions contain [6] [7]. Judkiewicz et al showed intraarticular extension of melorheostosis in35% of cases in their series [6]. It may result from mineralization of soft tissue masses associated with melorheostosis or be related to mechanical cartilage damage with resultant osteochondral fragments. Bone scintigraphy may be instrumental in confirming the diagnosis in equivocal cases [8]. A three phase Tc-99m scintigraphy shows moderately increased uptake of the radiopharmaceutical. Histpopathological examination shows variable degree of marrow fibrosis along with irregular bone with mixed areas of lamellar and woven bone. Soft tissue masses show osteocartilaginous, fibrovascular and adipose tissue components. Haversian system is intact with no evidence of inflammation [7] [2]. Osteopoikilosis is differentiated from melorheostosis by symmetrical involvement, absence of soft tissue involvement, negative scintigraphy, no clinical complaints and autosomal dominancy [2]. Localised melorrheostosis should be differentiated from myositis ossificans, calcified hematoma and parosteal osteosarcoma. Other sclerosing dysplsias are more diffuse and have negative scintigraphy. Jaffe –Lichenstein polyostotic fibrous dysplasia is one sided but shows more frequent osteolytic areas and its histopathological changes. Caffey s disease shows less dense periosteal reaction and is found in different locations. Ollier s disease, neurofibromatosis, tuberous sclerosis and Engelmann s disease can sometimes look like melorheostosis [5]. In conclusion, radiographs are diagnostic for melorheostotic lesions. MR imaging is useful to detect the presence and extent of associated mineralized and nonmineralised soft tissue masses and may obviate unwarranted biopsy and a radical procedure. Differential diagnosis: MELORHEOSTOSIS Diagnosis confirmation: Expert' opinion Category: Musculoskeletal Region / Organ: Leg-Bones Etiology: unknown References: 1. Murray R, McCreide J: Melorrheostosis and the Sclerotomes: A Radiological Correlation. Skeletal Radiology 4:57-71, 1979. 2. Green A., et al. Melorrheostosis and osteopoikilosis. AJR87: 1096-1111, 1962. 3. Hellemans J., Preobrazhenska O., Willaert A. et al. lossof function mutations in LEMD3 result in osteopoikilosis, Buschke-ollendorff syndrome and Melorrheostosis. Nature Genet. 36:1213-1218, 2004. 4. Debeer P., Pykels E., Lammens J. et al. Melorrheostosis in a family with autosomal dominant osteopoikilosis. Am. J. Med. Genet. 119A:188-193, 2003. 5. Resnik D. and Niwayama G. In : Diagnosis of bone and joint disorders, 3rd edition. D. Resnik, editor. W.B. Saunders Co., Philadelphia, 1995. Vol.6 pages 4396-4415. 6. Judkiewicz Aron et al. Advanced imaging of Melorrheostosis with emphasis on MRI. Skeletal Radiology. 30:447-453,2001. 7. Yu J., Resnik D. et al. Melorrheostosis with an ossified soft tissue mass: MR features. Skeletal Radiology 24:367-370, 1995. 8. Greenspan A. and E.M. Arzouz. Bone dysplasia series. Melorheostosis: Review and update. Get more for MELORHEOSTOSIS Peer-reviewed resources Literature  More publications about MELORHEOSTOSIS |