BONE MORPHOGENETIC PROTEIN-2 4 IN EARLY FIBROMATOUS LESIONS OF FIBRODYSPLASIA OSSIFICANS PROGRESSIVA/

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by congenital malformation of the great toes and progre ssive heterotopic ossification in distinct anatomic patterns. Early pr eosseous lesions in FOP are clinically and histologically indistinguis hable from the lesions of aggressive juvenile fibromatosis (AJF). Alth ough the genetic defect in FOP is unknown, bone morphogenetic proteins (BMPs) 2 and 4 are plausible candidates genes. To determine if there is a difference in BMP 2/4 expression in the early fibromatous lesions of the two conditions, we performed immunohistochemical studies with a monoclonal antibody to BMP 2/4 on the earliest detectable fibromatou s lesions of FOP and compared them with histologically identical lesio ns resected from children who had AJF. Fibromatous cells from the earl y FOP lesions exhibited immunostaining for BMP 2/4, whereas histologic ally indistinguishable fibromatous cells from AJF lesions showed no ev idence of BMP 2/4 immunostaining. It is incumbent on all physicians wh o treat patients with suspected fibromatosis to examine the toes to ru le out FOP and to avoid unnecessary diagnostic biopsies because surgic al trauma induces further bone formation in patients who have FOP. How ever, if diagnostic confusion still exists and a biopsy is performed, immunostaining with BMP 2/4 antibody may resolve the diagnostic dilemm a between FOP and AJF before the appearance of heterotopic ossificatio n is observed in the FOP lesions. Our data suggest that the BMP 2/4 su bfamily of secreted proteins may be involved in the pathogenesis of th e FOP lesions. Copyright (C) 1997 by W.B. Saunders Company.