CD10 expression helps to differentiate basal cell carcinoma from trichoepithelioma*

BACKGROUND The distinction between basal cell carcinoma (BCC) and trichoepithelioma (TE) may be very difficult in some cases because of the close similarities of these two lesions clinically and histopathologically. The purpose of this study is to investigate the usefulness of CD10 in distinguishing BCC and TE. METHODS The immunohistochemical expression of CD10 was evaluated in an archived group of 30 BCCs and 12 TEs in a retrospective cross sectional study. The localization of anti-CD10 to the tumoral and/or stromal cells was determined in each case and was compared between these two tumors using Fisher's Exact Test. RESULTS In BCC cases, the expression of CD10 was noted in tumoral cells in 26 cases (83.2%). Of these, 3 cases showed positivity of the stromal and basaloid cells, two cases demonstrated stromal expression alone and two BCCs were not immunoreactive. On the other hand, 10 out of 12 (83.3%) TEs showed positive stromal immunoreactivity. Of these, one case also showed positivity of the basaloid cells. One TE demonstrated epithelial expression alone and one TE was not immunoreactive. The pattern of staining of basaloid cells and stromal cells in BCC and trichoepithelioma was statistically different (p < 0.001). CONCLUSIONS We conclude that CD10 is a useful marker in the differential diagnosis of BCC versus TE.