Perforin expression in eyelid sebaceous carcinomas: a useful and specific immunomarker for the differential diagnosis of eyelid carcinomas

Purpose Eyelid sebaceous carcinoma ( SC ) remains a common diagnostic pitfall for both the clinician and histopathologist. The aim of this study was to describe perforin as a new marker in the immunohistochemistry panel for SC . Methods A total of 29 cases were retrieved from the P athology archives, including 11 sebaceous neoplasms (nine SC ; two sebaceomas), 10 squamous cell carcinomas ( SCC ) and eight basal cell carcinomas ( BCC ). These were stained using the monoclonal antibody for perforin, epithelial membrane antigen ( EMA ), Ber‐ EP 4 and adipophilin ( ADP ). Sensitivity and specificity of perforin as an immunohistologic marker for sebaceous tumours were compared to EMA , ADP and Ber‐ EP 4. Results Perforin stained strongly 9/11 (81%) of the sebaceous neoplasms ( SN ), 7/9 SC and 2/2 of sebaceomas (2/2), similar to ADP . Epithelial membrane antigen (EMA) stained 8/9 SC and was negative (1/2) or only very weakly expressed (1/2) in sebaceomas. The specificity of perforin in identifying SN versus SCC and BCC was 100% (95% CI 69–100), while EMA specificity in identifying SN varied according the comparison group ( SCC : 50%, 95% CI 18–81, 100% (95% CI 63–100). Perforin better highlighted the intraepithelial spread of SC than EMA . Ber‐ EP 4 was strongly expressed in six of nine SC , but was consistently negative in sebaceomas. Conclusions The expression pattern of perforin in sebaceous neoplasms enables us to recommend the use of perforin as a new immunohistochemical marker for sebaceous neoplasms.