The Many Faces of Superficial Basal Cell Carcinoma -Clinicopathological and Immunohistochemical Studies of Three Different Lesions-

Superficial basal cell carcinoma is a distinct variant of basal cell carcinoma not only histological- ly but also biologically. Its indolent growth and occasionally misleading clinical presentation can sometimes pose a diagnostic challenge to clinicians. In this report, we describe three lesions of super-ficial basal cell carcinoma in two Taiwanese patients.Their clinical appearances were drastically dif-ferent from each other. The histopathology of the three lesions varied in the aspects of the tumor islands and the components of peritumoral stroma. The diverse clinicopathological pictures of superfi-cial BCC demonstrate the complex and conditioned pathogenesis of the tumor. In addition, immuno-histochemical studies with Ki-67 and bc1-2were performed on our cases and two cases of trichoep-ithelioma as well. Ki-67 is epressed in a random fashion within the tumor nests of superficial BCC, while trichoepithelioma is barely positive with Ki-67. Diffuse staining of bc1-2 is seen on the tumor nests of superficial BCC. In contrast, only the periphery of the tumor nests is bc1-2 positive in tri-choepithelioma. The differential immunostaining profile of the two lesions reflects their respective biological behaviors and may be of value in separating the two conditions in certain problematic cases.