Squamous carcinoma in scars: clinicopathological correlations.

Twelve cases of squamous cell carcinoma arising in scars of the skin are analyzed. Correlation of tumor aggressiveness, tumor differentiation, intensity of small lymphocyte infiltration, and nature of adjacent collagen tissue to tumor stroma was investigated. All tumors were predominantly well differentiated. Nine patients had no metastasis or recurrence after surgical treatment of the primary tumor. Three patients developed widespread metastases and died less than 2 years after operation. The tumors of these latter patients contained areas of pleomorphic and spindle cells and had minimal infiltrates of small lymphocytes. In contrast, the 9 patients who remained free of tumor had moderate infiltrates of small lymphocytes, and in just 1 of 9 was an area of pleomorphic tumor cells found. Prognosis in scar carcinoma, therefore, may be related to tumor differentiation and the degree of host response with small lymphocytes to the tumor, rather than to the universally poor prognosis recorded in the past.