Plexiform fibrohistiocytic tumor without multinucleated giant cells: a case report.

Plexiform fibrohistiocytic tumor (PFT) is a rare but distinctive soft tissue tumor of children and young adults characterized by a mixture of histiocyte-, myofibroblast-, and osteoclast-like giant cells arranged in a plexiform pattern. We report the clinicopathologic and immunohistochemical features of an apparently unique case of PFT without multinucleated giant cells presenting in a 3-year-old child. Light microscopy revealed a subcutaneous tumor composed of a plexiform proliferation of histiocyte- and myofibroblast-like cells. Multinucleated osteoclast-like giant cells, the third classic cellular component of this mesenchymal neoplasm, were not observed. The differential diagnosis is also discussed. Emphasis is placed on the importance of the recognition of PFT, because it may exhibit an aggressive behavior.