Histologic subtyping and malignancy assessment of cutaneous squamous cell carcinoma

BACKGROUND. Squamous cell carcinomas (SCCs) of the skin have a wide range o f histologic subtypes and there are indications of differences in prognosis . OBJECTIVE. The morphologic variety of SCCs with respect to its biological b ehavior and the further course of disease is analyzed, with emphasis on his topathologic criteria, briefly quoting the main clinical and pathogenetic a spects. METHODS. Referring to the international tumor classification of the World H ealth Organization, histologically different carcinoma variants are present ed and discussed, based on a review of the literature regarding each subtyp e, and also including the desmoplastic SCC type. RESULTS. Histologically, common invasive SCCs are most frequently found, wh ile metastases mainly occur in tumors of high thickness and poor differenti ation. The immature spindle cell carcinoma type resembles sarcoma and may g row rapidly with an aggressive clinical course. Lymphoepithelioma-like carc inoma of the skin is extremely rare and its histogenesis remains to be eluc idated. Thus far, one case with metastasis and lethal outcome has been repo rted. As details determining the progression ability have so far only been scanty and partially contradictory, more investigations are necessary, espe cially for acantholytic SCCs and invasive SCCs developing from Bowen's dise ase, whereas verrucous carcinomas can be categorized as low malignancy neop lasms. Desmoplastic SCCs, especially with large tumor thickness, should be separated from other SCC subtypes due to their high risk of local recurrenc e and metastatic spread. CONCLUSION. The future outcome of SCCs of the skin is significantly influen ced by their histologic grade and tumor thickness. In addition, subtyping r epresents another valuable histopathologic tool for improving the assessmen t of malignancy.