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.

We describe a pilomatricomal horn on the right arm of a 39-year-old man. Although initially the tumor was clinically thought to be a verruca vulgaris, the microscopic features were similar to those found in classic pilomatricoma, except for the epidermal location and the presence of a cutaneous horn. Light microscopy showed replacement of the epidermis by basaloid cells, with masses of cornified material containing shadow cells that formed a cutaneous horn. Whereas classic pilomatricoma is confined to the deep reticular dermis or subcutis, the present case represents a unique heretofore unreported epidermal variant of pilomatricoma that pathologists should be aware of to differentiate it from malignant epidermal tumors.

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