Cutaneous inflammatory pseudotumor: a case report with immunohistochemical and ultrastructural studies.

An unusual case of inflammatory pseudotumor of the subcutaneous tissue in a 44-yr old black male who presented with a 4 cm soft tissue mass on the dorsum of right hand is described. The mass was sharply circumscribed and composed of a polymorphous infiltrate of plasma cells, eosinophils, lymphocytes and some giant cells mimicking Reed-Sternberg cells. The giant cells, corresponding ultrastructurally to primitive mesenchymal cells, were immunoreactive for vimentin and were negative for actin, desmin and histiocytic markers. The patient remained well with no sign of recurrence 8 mths postoperatively. The present case is compared with the (4) previously reported cases in literature. The histologic differentiation from other neoplastic and non-neoplastic lesions is discussed.