Immunohistochemical staining for adipophilin, perilipin and TIP47

Background: The presence of lipid in the cell cytoplasm is useful for supporting the diagnosis of sebaceous gland carcinoma ( SGC). Currently this requires histochemical stains that are carried out on frozen sections of unprocessed tissue. Recently, several anti-adipocytic antibodies that recognise proteins associated with lipid vesicles have been described. These antibodies can be applied to paraffin-wax sections. Aim: To assess the ability of anti-adipocytic antibodies to identify intracytoplasmic lipid in SGC. Methods: Immunohistochemistry with a monoclonal antibody to adipophilin and polyclonal antibodies to perilipin and TIP47/PP17 was carried out on archival, formalin-fixed, paraffin- wax- embedded sections of 26 samples of SGC. The immunostaining was compared with 22 other eyelid tumours ( 11 basal cell carcinomas ( BCC), 10 squamous cell carcinomas ( SCC) and 1 Merkel cell tumour). Results: Immunohistochemical staining was positive in 23, 10 and 2 cases of 26 SGC with adipophilin, perilipin and TIP47, respectively. The positive staining identified cytoplasmic lipid vesicles. Anti-adipophilin was positive in five other eyelid tumours ( 4 BCC and 1 SCC) staining small cytoplasmic granules that can be easily distinguished from the staining in SGC. Conclusions: Immunohistochemical staining for adipophilin and perilipin is a useful ancillary technique for the demonstration of lipid in SGC that may be applied to paraffin- wax sections.