Sclerosing squamous cell carcinoma of the skin, an underemphasized locally aggressive variant: a 20-year experience.

BACKGROUND Desmoplastic (sclerosing) responses to a variety of neoplasms have been documented but rarely evaluated in association with primary cutaneous squamous cell carcinoma (SCC). We report a distinctive variant of SCC demonstrating an infiltrative growth pattern and stromal desmoplasia. METHODS Cases were identified through a retrospective review of our dermatopathology and dermatologic surgery databases. After initiation of the study, additional cases were identified prospectively. Neoplasms were scored microscopically for specific histopathologic parameters and reactivity with selected histochemical and immunohistochemical stains. Clinical follow-up data were obtained through a review of medical records or contact with the patient's referring physicians. RESULTS Seventy-three carcinomas from 72 patients were identified (46 men, 26 women; median age 76, range 45-91). The original pretreatment biopsies were available in 69 of 73 cases. All lesions developed on sun-damaged skin, with the cheek constituting the most common site. The clinical presentation was typically as a sclerotic plaque. All neoplasms extended into the reticular dermis or subcutaneous fat, and perineural invasion was identified in 53 cases (73%). Patients who underwent standard excisional surgery experienced a recurrence rate of 80%; 9% of those treated with micrographic surgery experienced postoperative recurrences. Metastasis or carcinoma-related death was not observed in any patient during the follow-up period (median 36 months). CONCLUSIONS Our results suggest that desmoplasia is uncommonly found in association with cutaneous SCC but helps define a locally aggressive variant of carcinoma. In light of the infiltrative nature of desmoplastic SCC of the skin and the high incidence of perineural invasion, micrographic surgery is the surgical modality of choice. The authors have indicated no significant interest with commercial supporters.