Peritumoral matrilin-2 staining may be useful in distinguishing basal cell carcinoma from folliculocentric basaloid proliferation.

Background: Folliculocentric basaloid proliferation (FBP) is a benign and reactive proliferation which can histopathologically mimic basal cell carcinomas (BCCs). The incidental presence of FBP during the excision of a BCC can occasionally lead to excessive tissue removal. One distinguishing feature of BCCs is that they invade the stroma, whereas FBPs generally do not.

Methods: Matrilin-2 is an extracellular matrix protein associated with tumor invasion, and we compared the expression of matrilin-2 in peritumoral cells of BCC and FBP.

Results: We found increased matrilin-2 expression within the peritumoral stroma of 41 of 42 BCCs (97.7%), with strong expression in all (100%) cases of infiltrative subtypes and in 21 of 25 (84%) nodular subtypes of BCC. We found no expression of peritumoral matrilin-2 in any of the seven cases of FBP.

Conclusion: Our results suggest that immunolabeling with the matrilin-2 antibody may help distinguish BCCs from FBPs.