Application of immunohistochemical staining of bcl-2, Ber-EP4, CD10, CK20, and Ki-67 in differential diagnosis between trichoblastoma and basal cell carcinoma

Abstract

Objective: To study the utility of immunohistochemistry (IHC) in differential diagnosis between trichoblastoma (TB) and basal cell carcinoma (BCC). Methods: Fifty-eight cases of TB and 40 cases of BCC were collected at Fudan University Shanghai Cancer Center from January 2009 to December 2019 and retrospectively analyzed by IHC for bcl-2, Ber-EP4, CD10, CK20 and Ki-67. Fisher exact test was performed for statistical analysis. Results: Twenty-five (43.1%) TBs and 5 (12.5%) BCCs showed bcl-2 staining in the outermost layer of the epithelial nests, the difference was statistically significant (P<0.01). The proportion of cases with bcl-2 staining>75% of epithelial cells in BCC group was much higher than that in TB group (40% vs. 12.1%; P<0.01). BCC group showed larger proportions with Ber-EP4 staining>75%, 51%-75% of epithelial cells than TB group (12.5% vs. 1.7%, 37.5% vs. 8.6%;P<0.05). Fifty-five (94.8%) TBs demonstrated CD10 expression in the follicular stroma, while only 16 (40.0%) BCCs showed focal or scattered CD10 expression in reactive fibrous stroma (P<0.01). CK20 expression was present in 37 (63.8%) TBs with scattered pattern, but BCCs exhibited no CK20 staining except for only one case (2.5%) showing focal staining (P<0.01). Compared with TB group, the BCC group included more cases with Ki-67 labeling index ≥15% on average and ≥25% in hotspot areas (P<0.05). Conclusion: IHC is helpful in differential diagnosis between TB and BCC. Scattered CK20 staining pattern and stromal CD10 expression support the diagnosis of TB. Bcl-2 staining limited to the outermost layer of the proliferation is more likely to be found in TB. In contrast, Ber-EP4 positivity and higher Ki-67 labeling index tend to be present in BCC.