[1]: 612 Plexiform fibrohistiocytic tumor appears as a painless, slowly expanding soft tissue mass located in the dermis and subcutis.
[3] The upper extremities were more commonly affected by plexiform fibrohistiocytic tumors.
[7] There are three main well-documented histologic patterns that have been identified: a fibrohistiocytic subtype that consists of plexiform clusters of mononuclear histiocyte-like cells and multinucleated giant cells; a fibroblastic subtype that consists primarily of elongated clusters and short fascicles of spindle fibroblast-like cells; and a mixed subtype that consists of equal parts of both patterns.
[5][8] The fibroblastic cells show uniform reactivity to vimentin and at least focal reactivity for smooth muscle actin, while the histiocytic cells of plexiform fibrohistiocytic tumor stain for CD68 (KP-1).
[2] Differential diagnoses of plexiform fibrohistiocytic tumor include plexiform schwannoma, plexiform neurofibroma, cellular neurothekeoma, deep benign fibrous histiocytoma, fibrous hamartoma of infancy, dermatofibroma, benign and malignant soft tissue giant cell tumor, and myofibromatosis.