Table 3

 Useful histological and immunohistochemical features for distinguishing between basal cell carcinoma and trichoepithelioma

FeatureBCCTE
BCC, basal cell carcinoma; CK, cytokeratin; TE, trichoepithelioma.
HistologyIncreased mitosesMitoses not increased
Retraction spacesRetraction spaces not present
Usually no horn cystsHorn cysts usually present
Stromelysin 3Positive in stromaNegative
    CD10Positive in basaloid cellsPositive in stroma
    CD34NegativePositive in stroma
    Bcl-2Diffusely positive in basaloid cellsPositive in peripheral cells only
    Ki-67Increased (20–40%)Normal (rare cells)
    CK 15NegativeFocally positive
    CK 20NegativeFocally positive