Nodular fasciitis of the hand: a potential diagnostic pitfall in fine-needle aspiration cytopathology.

Fine-needle aspiration biopsy (FNAB) is applied very uncommonly to soft tissue masses and even more infrequently to lesions of the hand. Nodular fasciitis, an uncommon pseudosarcomatous lesion of soft tissue, rarely occurs in the hand and, because of this, is not often considered in the differential diagnosis of hand masses. We report 3 cases (2 men and 1 woman; mean age, 44.3 years) of soft tissue masses of the hand, which, after clinical and radiologic evaluation, were strongly suspected by an experienced orthopedic oncologist as harboring a soft tissue sarcoma. Each patient underwent FNAB, which showed markedly hypercellular smears with overlapping, relatively isomorphic spindle cells that were mistaken cytologically as possible sarcoma in 2 cases; 1 case was considered probable nodular fasciitis. All lesions eventually were diagnosed as nodular fasciitis after thorough histologic and immunohistologic evaluation. Nodular fasciitis remains a difficult diagnosis by FNAB, particularly when it occurs in locations such as the hand.