Cytology of metastatic cutaneous basal cell carcinoma.

Although basal cell carcinoma is the most common malignant skin tumor, it rarely metastasizes. Because of the infrequency of basal cell carcinoma metastases, the cytomorphologic findings have not been well documented. We retrospectively reviewed the cytologic findings of six cases of metastatic basal cell carcinoma from two patients. Five of these specimens were fine-needle aspiration biopsies, and one was a bronchial brush specimen. All cases were confirmed by and compared to either the concurrent tissue biopsy or to a previous surgical specimen. The microscopic findings of these specimens reveal tight clusters of cells with high nuclear to cytoplasmic ratio. The nuclei were crowded and overlapping, and on Diff Quik stain, peripheral palisading of nuclei could be appreciated. The small hyperchromatic nuclei were round to oval with finely granular chromatin. Nucleoli were inconspicuous. Basophilic cytoplasm was scant with indistinct borders. Cytologic findings of basal cell carcinoma have not been well documented in the English literature. Our experience suggests that there are unique cytormorphologic features of metastatic basal cell carcinoma and that in the right setting such a diagnosis can be rendered.