Neuroendocrine differentiation in basal cell carcinoma. An immunohistochemical study

Neuroendocrine differentiation in basal cell carcinoma (BCC) of the skin has been reported in the past on the basis of ultrastructural findings, argyrophilia, and the immunohistochemical detection of neuropeptides in such neoplasms. To assess further the relative frequency of neuroendocrine differentiation in BCC, paraffin sections of 53 randomly chosen cases were evaluated for Churukian-Schenk stain positivity and the expression of sensitive neuroendocrine markers. These included neuron-specific enolase (using a highly absorbed monospecific antiserum), chromogranin-A, synaptophysin, neurofilament protein, and Leu-7 antigen. Although 25% of cases demonstrated argyrophilia with the Churukian-Schenk method, suggesting a high frequency of possible neuroendocrine differentiation, immunohistochemical evidence of the same was observed in only two tumors (4%). These demonstrated immunoreactivity for chromogranin and neuron-specific enolase. The results of this analysis suggest that neuroendocrine differentiation in BCC is relatively uncommon, and that it is not reliably predicted by the results of argyrophil stains done on paraffin sections.