Clinicopathologic Features of Eyelid Sebaceous Gland Carcinoma Requiring Immunohistochemical Diagnosis.

Introduction: The aim of the study was to evaluate the clinicopathological features of eyelid sebaceous gland carcinoma (SGC), which requires immunohistochemical examination for a definitive diagnosis. Methods: Twenty-seven patients with a final diagnosis of eyelid SGC at Toyama University Hospital between April 2016 and April 2022 were retrospectively studied. In cases with a strong clinical suspicion of SGC, if the initial pathological diagnosis by hematoxylin-eosin staining was non-SGC, additional detailed pathology was performed, including immunostaining for adipophilin (ADP) and androgen receptor (AR). Results: Five patients (18.5%) had a diagnosis other than SGC, including three with squamous cell carcinoma (SCC), one with basal cell carcinoma, and one with Bowen disease. In these 5 cases, detailed pathology, including immunostaining for ADP and AR, was performed again, which ultimately led to the diagnosis of SGC. ADP was positive in all 5 cases, and AR was positive in 4 cases. The 3 patients diagnosed with SCC were characterized by a high Ki-67 index, active mitosis, and relatively low differentiation. Conclusion: SGC can be pathologically diagnosed in other cancers, such as SCC and BCC. When SCC was diagnosed, it was often hypo-differentiated and required more attention. Immunostaining for ADP and AR is invaluable for confirming SGC diagnosis.