Abstract

Basal cell carcinoma (BCC) is characterized by islands of basaloid cells with peripheral palisading and stromal retraction. Rarely, the tumor cells have clear cytoplasm, while maintaining other characteristic features. A portion or nearly all the BCC may contain clear cell changes. Pale-cell morphology may also occur.  Differentiating clear cell BCC from other clear cell tumors such as sebaceous carcinoma, clear-cell squamous cell carcinoma, hidroadenocarcinoma, trichilemmal carcinoma, balloon-cell melanoma, and metastatic clear-cell renal carcinoma is important, as it may have therapeutic and prognostic significance. BerEP4 expression supports BCC. Negative differentiating stains include, adipophilin, EMA, CEA, melanocyte markers such as SOX10, CD34, PAX8, and CD44.

We present three cases of clear-cell BCC. Case 1, on the eyelid of a 75-year-old female, Case 2 on the scalp of an 82-year-old woman and Case 3 on the scalp of a 71-year man. All showed histopathology that included lobules of cells with clear cytoplasm, peripheral palisading of nuclei and expression of BerEP4. Case 1 showed nodular architecture, nearly all of which had clear cells that were negative for CD34/INSM1/EMA/adipophilin/PAX-8. Case 2 was a superficial and nodular BCC, with conventional and clear cell lobules that were negative for CD34 and EMA. Case 3 was conventional nodular BCC with a pale and focally clear cell component. These cases demonstrate variable presentations of the rare clear cell BCC variant and highlight the importance of recognizing the rare occurrence on the eyelid, which may be mistaken for sebaceous carcinoma.