title: Atypical decubital fibroplasia in a young patient with melorheostosis.
abstract: A case of atypical decubital fibroplasia of the right forearm arising in a 25-year-old male with melorheostosis is presented. The diagnosis of melorheostosis involving the right-sided bones was made by radiographical studies, and the patient has been obliged to use crutches due to the contracture and limited range of motion of the right leg. Two painless masses occurred in the subcutis of the posterior aspect of the right forearm over the excrescences of the underlying ulna due to melorheostotic deformity. Grossly, ill-defined firm masses, which measured 3 x 6 x 1.5 cm and 4 x 5 x 1 cm, respectively, were white and intermingled with yellow fatty tissue. Histologically, the lesions consisted of a proliferation of plump fibroblastic cells with abundant collagenous stroma. Vascular proliferation and occasional eosinophilic degeneration of the collagen fibers were also seen. The gross and histological features were those of atypical decubital fibroplasia (ischemic fasciitis). Immunohistochemically, the plump fibroblastic cells were positive for vimentin, but negative for desmin, muscle specific actin, and alpha-smooth muscle actin. Chondroid metaplasia was focally noted and round-shaped cells within this area were positive for S-100 protein. This lesion seemed to be a fibroblastic response against the long-standing, intermittent ischemia of the subcutaneous tissue between the bony excrescences due to melorheostosis and the weight-bearing forces of the crutch.
authors.affiliation: Department of Pathology, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Ishida
authors.forename: R
authors.initials: R
authors.lastname: Machinami
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D005208:Fasciitis / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D005355:Fibrosis / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008557:Melorheostosis / Q000150:complications* / Q000000981:diagnostic imaging; D011859:Radiography; D014746:Vimentin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D014746:Vimentin