Intratendinous aponeurotic fibroma.

Juvenile aponeurotic fibroma is a distinctive fibroblastic tumor usually found in young children. The tumor has a predilection for the palms and soles, although it can occur elsewhere, either superficially in subcutaneous tissues or in deeper musculofascial and paraskeletal tissues. In this case the tumor occurred in an adult within the substance of the flexor pollicis longus tendon, a location not previously reported in the literature. Because of the unique location of the tumor, it was excised without sacrificing the tendon. Since recurrence of these lesions is common, continued observation was necessary. Magnetic resonance imaging in this patient 26 months after the operation showed restoration of the normal tendon contour.