Immunohistochemistry in the Differential Diagnosis of Cutaneous Basal Cell Carcinoma

Basal cell carcinoma and squamous cell carcinoma are two of the most common cutaneous tumors seen by pathologists. In the large majority of cases, the distinction between these two tumors is readily made on the basis of standard H&E morphology. However, many of us see cases from time to time that for one reason or another (minuscule biopsy, mishandled specimen, crushed beyond recognition, dryed out, poorly fixed, etc., etc.), it is difficult to know for certain whether one is dealing with a squamous carcinoma or a basal cell carcinoma. This month, we discuss several immunostains that can be of utility in approaching this problem. It is worth mentioning that both basal cell carcinoma and cutaneous squamous cell carcinoma characteristically express strong and diffuse high molecular weight cytokeratin, cytokeratin 5 (or cytokeratin5/6) and nuclear p63, so the absence of staining with these markers (assuming adequate tissue and technique of course) should lead you to consider another diagnosis. EMA is a useful antibody for this problem, since basal cell carcinomas are negative for EMA, although occasionally lumina associated with sebaceous differentiation in these tumors may show EMA positivity. In contrast, most squamous cell carcinomas of the skin will have substantial EMA immunoreactivity.Ber-EP4 is also a useful marker, as basal cell carcinomas are typically positive for this marker, unlike cutaneous squamous carcinoma. Interestingly, non-cutaneous squ...
Source: Oncopathology - Category: Cancer & Oncology Source Type: blogs