SCC of the hair follicle represents a poorly recognized but distinctive subset of SCC of the skin that should be considered in the differential diagnosis of other cutaneous epithelial tumors. The term follicular SCC (FSCC) is proposed for this neoplasm.

p53 protein plays an important role in control of cell proliferation by suppressing proliferation of cells with DNA damage. Mutations of the p53 gene increase the stability of the encoded nonfunctional protein which accumulates in the nuclei, allowing it to be detectable by immunohistochemistry. Mutant p53 protein has been observed in preneoplastic and neoplastic conditions supporting its role in the development of some human cancers. In this immunohistochemical study, we examined p53 expression in 12 Dermatofibrosarcoma Protuberans (DFSP) and 10 Dermatofibromas (DF). Results were compared with the cellular proliferation rate by using the monoclonal antibody Mib-1 which detects Ki-67 antigen expression. Nuclear accumulation of the p53 protein was observed in 11 DFSP. All DF were negative for p53. No statistical correlation could be established between p53 and Mib-1 staining in our cases. We conclude that mutations of the p53 gene may be involved in the molecular pathogenesis of DFSP but not of DF. Mib-1 index can not be successfully used to distinguish DFSP from DF.

Giant cell fibroblastoma is a rare mesenchymal neoplasm of unknown origin and uncertain clinical course. The neoplasm has been considered by some authors as a juvenile variant of dermatofibrosarcoma protuberans. We report a patient with giant cell fibroblastoma, now 28 months following surgical removal, in which the neoplasm was characterized histologically by a proliferation of spindle-shaped cells intermixed with pseudovascular channels called "angiectoid spaces." The spaces were lined by large cells with pleomorphic nuclei intermixed with multinucleated cells. Immunohistochemically, the tumor stained diffusely for vimentin and CD34, a surface glycoprotein expressed by some mesenchymal neoplasms including dermatofibrosarcoma protuberans. We postulate a mechanism of formation of the angiectoid spaces based on histopathological findings in serially sectioned portions of the neoplasm. Positive staining of tumor cells for CD34 supports a possible relationship of the neoplasms with dermatofibrosarcoma protuberans.