Plexiform fibrohistiocytic tumor]

Plexiform fibrohistiocytic tumour has been recently described by Enzinger and Zhang. This is a rare tumour with low grade malignancy which requires large excision. We report two cases, one occurring in a 58-year-old man, presenting a voluminous painless mass of 5 cm on his hand, the other occurring in a 9-year-old boy consulting for a nodule on the chest. On histological examination this dermal hypodermal tumour is characterized by a proliferation of histiocytic-like cells grouped in nodules, where they are associated with multinucleated osteoclastic-like cells and a proliferation of fibroblastic-like cells grouped in fascicles, anastomosing in a plexiform pattern. Immunohistochemistry and ultrastructural aspects are described. Differential diagnosis and histogenesis are discussed.