Atypical decubital fibroplasia in a young patient with meiorheostosis

A case of atypical decubital fibroplasia of the right forearm arising In a 25‐year‐old male with meiorheostosis is presented. The diagnosis of meiorheostosis 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 subcutls of the posterior aspect of the right forearm over the excrescences of the underlying ulna due to melorheostotlc deformity. Grossly, ill‐defined firm masses, which measured 3×6×1.5 cm and 4×5×1 cm, respectively, were white and intermingled with yellow fatty tissue. Histologically, the lesions consisted of a proliferation of plump flbroblastlc cells with abundant collagenous stroma. Vascular proliferation and occasional eosinophilic degeneration of the collagen fibers were also seen. The gross and hlstologlcal features were those of atypical decubital fibroplasia (ischemlc fasciltis). Immunohlstochemlcally, the plump flbroblastic cells were positive for vimentin, but negative for desmin, muscle specific actln, and α‐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 flbroblastlc response against the long‐standing, Intermittent ischemia of the subcutaneous tissue between the bony excrescences due to meiorheostosis and the weight‐bearing forces of the crutch.