In the May 1994 issue of the Archives, there appeared an interesting article stating that immunostaining for CD34 can differentiate basal cell carcinoma from trichoepithelioma.1 We were intrigued by this finding and attempted to confirm it.
From a collection of neoplasms, 10 examples each of trichoepithelioma (generally from patients with known epithelioma adenoides cysticum), basal cell carcinoma in which there was pilar differentiation, morpheiform basal cell carcinoma, desmoplastic trichoepithelioma, and syringoma were stained using antibody to CD34 and standard techniques. Positive staining of endothelial cells served as an internal positive control in each case.
Our results were disappointing. All sections contained appropriate staining of vessels and the characteristic smear around the lower portions of hair follicles and sweat gland coils.2 We agree with Drs Kirchmann and colleagues that there was a preference for staining of the stroma surrounding trichoepitheliomas when compared with the staining pattern surrounding basal cell