Background: Sebaceous carcinoma is a rare malignant adnexal neoplasm that predominantly affects the periocular region and may mimic other epithelial malignancies. Immunohistochemistry is particularly useful when sebaceous differentiation is inconspicuous. The present study aimed to evaluate the histomorphological features of sebaceous carcinoma and correlate them with immunohistochemical findings.

Materials and Methods: A retrospective descriptive study was conducted on 10 histopathologically confirmed cases of sebaceous carcinoma. H&E-stained sections were evaluated for tumour architecture, differentiation, sebaceous differentiation, nuclear pleomorphism, hyperchromasia, mitotic activity, necrosis and infiltrative growth. Immunohistochemical expression of adipophilin, epithelial membrane antigen (EMA), androgen receptor (AR) and Ber-EP4 was assessed using a semiquantitative composite scoring system.

Results: The mean age was 62.4 ± 11.8 years, with 60% of patients aged >60 years and 60% being female. The upper eyelid was the commonest tumour site (40%). Nuclear pleomorphism was present in all cases, while lobular/irregular architecture, hyperchromasia, sebaceous differentiation and increased mitotic activity were observed in 90%, 90%, 80% and 80% respectively. Infiltrative growth was present in 70% and necrosis in 50%. Adipophilin and EMA showed positivity in 90% of cases, followed by AR in 80% and Ber-EP4 in 30%. AR positivity was observed in all well/moderately differentiated tumours but in only one poorly differentiated tumour (p=0.067). Adipophilin was positive in all cases with morphological sebaceous differentiation (p=0.20).

Conclusion: Histomorphology remains fundamental for diagnosis, while adipophilin and EMA provide valuable immunohistochemical support. An integrated morphological and immunohistochemical approach is particularly useful in diagnostically challenging and poorly differentiated sebaceous carcinomas.

KEYWORDS: Sebaceous Carcinoma, Sebaceous Differentiation, Adipophilin, Epithelial Membrane Antigen, Androgen Receptor, Immunohistochemistry, Histomorphology.