Spindle cell squamous carcinomas and sarcoma-like tumors of the skin: a comparative study of 38 cases.

Thirty-eight cutaneous lesions previously diagnosed as spindle cell squamous carcinoma, "atypical fibroxanthoma," or dermal sarcoma are presented. Two patients had two lesions each; thus, there were 36 patients. Cases of spindle cell melanoma (including desmoplastic melanoma), sarcoma of subcutaneous origin, and "neuroid sarcoma" were excluded. On review, the lesions fell into two categories: (1) those with a definite component of invasive squamous carcinoma in addition to sarcoma-like areas (8 cases), and (2) those in which such a squamous component was not identified (30 cases). Cases in the former group were considered proven spindle cell squamous carcinomas, while those in the latter group were designated noncommittally as sarcoma-like tumors. Almost all patients were white and over 40 years of age. Four sarcoma-like tumors (from three patients) arose in areas previously treated with x-ray and all but two (both spindle cell squamous carcinomas) of the remainder in both categories arose in sun-damaged skin. Prognosis did not differ significantly between the two categories but depended primarily on the depth of invasion. Two of two tumors that extended into bone and four of seven that invaded skeletal muscle caused death; all of those involving only dermis (24) or dermis and subcutis (five) were successfully extirpated. Origin in an area that had received x-ray was also an unfavorable prognostic indicator; all three patients whose lesions arose in such areas died of tumor. This may have been related to depth of invasion because the three fatal postradiation sarcoma-like tumors all invaded muscle. It was concluded that the distinction between spindle cell squamous carcinoma and "atyical fibroxanthoma" is of little prognostic import per se, but rather that prognosis is primarily dependent on the depth of invasion and, perhaps, the type of antecedent irradiation.