Atypical fibroxanthoma distinguishable from spindle cell carcinoma in sarcoma-like skin lesions. A clinicopathologic and immunohistochemical study of 21 cases

Abstract

A Clinicopathologic study was done of 21 cutaneous, sarcoma‐like lesions previously diagnosed as atypical flbroxanthoma, spindle cell carcinoma, or dermal sarcoma. These lesions were most commonly presented as a solitary, often ulcerated nodule, occurring on exposed skin of the face in the elderly or, occasionally, on roentgen‐damaged or burnt skin of the head, leg, or hand. Microscopic features of the 21 lesions were, however, not alike, thereby implying that such sarcoma‐like lesions had derived from heterogeneous origins. The immunohistochemical staining in a comparative study with two other cases of unequivocal spindle cell squamous carcinoma suggested that these lesions could be histogenetically divided into two different groups: (1) the major group of true atypical fibroxanthoma, consisting of 19 cases, and (2) the minor group of probable spindle cell squamous carcinoma, consisting of 2 cases. Despite a wide histologic spectrum and of heterogeneity of these lesions, there was a benign clinical course in the majority, due in part to the small size and superficial location of the lesions.