Pigmented XXXX ( @entity241 ). A pathologic, ultrastructural, and immunohistochemical study.

@entity5 @entity4483 @entity3292 @entity241
Described by Bednar as a "storiform @entity3292 ," pigmented @entity241 is a rare @entity5 accounting for approximately 1-5% of all cases of @entity241 ( @entity241 ). The lesion commonly presents as an exophytic, multinodular @entity5 of the dermis or subcutaneous tissue. It occurs predominantly in blacks. The majority are located on the trunk, and the remainder are more or less equally distributed in the upper and the lower extremities and the head and neck. Microscopically the lesion is characterized by spindled cells arranged in a tight storiform pattern and admixed with a small population of melanin-containing dendritic cells. The dendritic cells are the primary feature distinguishing this lesion from conventional @entity241 . Three cell populations are identifiable by electron microscopy. The majority of cells resemble fibroblasts. A second population of cells exhibits long slender cell processes partially or completely invested by basal lamina. The third population of cells, also invested by basal lamina, contains both melanosomes and premelanosomes. The histogenesis of this @entity5 remains controversial. Although Bednar considered these lesions as variants of @entity3292 , @entity4483 protein could not be identified, and this finding contrasts significantly from the description of conventional @entity3292 , which almost always contains this antigen. Follow-up information available in nine cases indicates that this lesion may recur locally. Although distant metastases were not observed in our material, complete excision in conjunction with close follow-up care is indicated for this @entity5 of probable intermediate malignant potential.
