Diagnostic features of fibrodysplasia (myositis) ossificans progressiva on bone scan.

Fibrodysplasia ossificans progressiva (FOP) is a rare, autosomal dominant disorder of connective tissue that leads to progressive, disabling heterotopic ossification in characteristic anatomic patterns. It is accompanied by pathognomonic congenital malformation of the great toes (or thumbs) - microdactyly. There is a high occurrence of diagnostic errors in FOP, leading to inappropriate interventions that may result in significant harm to patients. Scintigraphic demonstration of heterotopic ossifications in connective tissue at characteristic locations, in combination with pathognomonic microdactyly of the great toes (or thumbs), is highly specific. The case presented here is aimed at increasing familiarity with those typical diagnostic features, especially on bone scintigraphy.