Intraosseous Schwannoma of the Distal Phalanx.

Intraosseous schwannomas are extremely rare and only a few cases involving the proximal phalanx and metacarpal of the hand have been reported. We report a patient with an intraosseous schwannoma of the distal phalanx. Radiographs showed lytic lesions in the bony cortex and enlarged soft shadows of the distal phalanx. The lesion was hyperintense to fat on T2-weighted magnetic resonance imaging (MRI) and strongly enhanced after gadolinium (Gd) administration. Surgical findings revealed that the tumour had developed from the palmar side of the distal phalanx and the medullary cavity was filled with a yellow tumour. The histological diagnosis was schwannoma. A definitive diagnosis of intraosseous schwannoma using radiography is difficult. In our case, a high signal was observed on Gd-enhanced MRI and histological findings showed areas with a high cellular area. Thus, Gd-enhanced MRI may help in the diagnosis of intraosseous schwannomas of the hand. Level of Evidence: Level V (Therapeutic).