CD117 and CD43 are useful adjuncts in the distinction of adenoid cystic carcinoma from adenoid basal cell carcinoma

Distinction of cutaneous adenoid cystic carcinoma (ACC) from adenoid basal cell carcinoma (BCC) is an occasional diagnostic dilemma in dermatopathology. We examined the immunohistochemical staining patterns with CD117 and CD43 in ACCs and BCCs, including BCCs with an adenoid growth pattern, to determine whether a combination of these markers can assist in the differential diagnosis. Fifteen cases each of ACC and BCC, including seven BCCs with a partial or entirely adenoid growth pattern were immunohistochemically stained for CD117 and CD43. The stains were interpreted semi-quantitatively. Staining for CD43 and CD117 was significantly more common in ACC than in BCC. Forty percent of ACCs showed staining for CD43, while no cases of BCC were positive. CD117 was positive in all cases of ACC, with 93% showing moderate or strong staining. BCC were less frequently positive, with only 20% of cases showing labelling of weak or moderate intensity. Immunohistochemical positivity for CD117 and CD43 are likely to be helpful adjuncts in the separation of cutaneous ACC from adenoid BCC.