Periocular Sebaceous Carcinoma: A Case Audit from the National Specialist Ophthalmic Pathology Service in Liverpool from 2009 to 2022 to Assess the Diagnostic Utility of PRAME Expression.

Introduction: Periocular sebaceous carcinoma (PSC) remains a common diagnostic pitfall both clinically and histomorphologically. PRAME (preferentially expressed antigen in melanoma) has been studied in the various neoplasms as proposed as diagnostic and therapeutic markers. PRAME is expressed in normal sebaceous units and in some sebaceous lesions; however, its utility in sebaceous carcinoma diagnosis has not yet been extensively investigated. We conducted a 13-year retrospective review of the patients diagnosed with PSC at the National Specialist Ophthalmic Pathology Service in Liverpool. Herein, we report the histomorphological and immunohistochemical (IHC) features of these tumors, particularly PRAME expression in this cohort. Methods: Thirty-one PSC cases diagnosed between 2009 and 2022 were retrieved from the histopathology archives. Twenty cases diagnosed as invasive PSC and 11 cases with in situ PSC were included. The hematoxylin and eosin (H&E) slides and previously performed IHC slides were reviewed; clinical information data were obtained. Cases with an adequate tissue were also stained for PRAME (preferentially expressed antigen in melanoma) and adipophilin (if not already performed). Results: In total, there were 24 females and 7 males diagnosed with PSC, ranging from 55 to 90 years (median, 78 years). The types of specimens received were 11 conjunctival mapping biopsies, 19 excisions/wedge resections, and 1 orbital exenteration. The eyelid was the commonest site involved ( Conclusions: Most PSCs are moderate-to-poorly differentiated. Although PRAME is expressed in normal sebaceous units, it appears less useful as diagnostic marker for PSC, especially in poorly differentiated tumors. In difficult cases, panels of IHC studies (adipophilin, Ber-EP4, and EMA) achieve a definitive diagnosis.