Basal cell carcinoma with eccrine differentiation

We describe a light, electron microscopic, and immunohistochemical study of basal cell carcinoma with eccrine differentiation. The cytoplasm did not stain with fat stain on cryostat sections, but contained numerous gland-like structures. Immunohistochemistry on formalin fixed, paraffin embedded tissues using antibodies to human involucrin, thirteen kinds of cytokeratin, S-100 protein, and carcinoembryonic antigen (CEA) was performed. We found that tumor cells were positive for keratin, PKK1, MA-903, No 8, No 19, AE 1, AE 3, and 5 + 8. Tumor cells were negative for S-100 protein, CEA, and the other antigens examined. Electron microscopy demonstrated short microvilli and amorphous materials within the intracytoplasmic cavity. We concluded that this tumor is basal cell carcinoma with eccrine differentiation.