Cytologic diagnosis of metastatic basal cell carcinoma. Report of a case with immunocytochemical and molecular pathologic considerations

BACKGROUND: Metastases of basal cell carcinoma (BCC) are extraordinarily rare events, with only about 200 published reports. The usefulness of immunohistochemical markers in the diagnosis of metastatic BCC was previously established on cytologic material. Furthermore, in recent years, numerous molecular markers have been studied to explain its pathogenesis and relatively indolent behavior. CASE REPORT: A 62-year-old, white male presented with lymphadenopathy in the right side of the neck. The patient had a long-standing history of multiple excisions of BCCs during the previous 30 years. Fine needle aspiration biopsy revealed tight clusters and sheets of small, round tumor cells with hyperchromatic nuclei, small nucleoli and minimal cytoplasm. In addition, in some of the clusters the tumor cells showed peripheral palisading. Based on the cytomorphology and diffuse immunohistochemical positivity for a low-molecular-weight cytokeratin marker, MNF 116, and negativity for AE1/AE3, Cam5.2, synaptophysin and chromogranin, a diagnosis of metastatic BCC was rendered. Subsequent histopathologic examination of metastatically involved lymph nodes removed in a radical neck dissection confirmed this diagnosis. In addition, on histologic sections the metastatic tumor cells were found to express bcl-2 and CD44, markers that have been recently studied in cutaneous tumors. CONCLUSION: In acquiring metastatic potential, this lesion did not lose the molecular characteristics of bcl-2 and CD44 expression, the two features deemed to be important in the indolent behavior of BCC.