Sebaceous gland carcinoma of the ocular adnexa - variability in clinical and histological appearance with analysis of immunohistochemical staining patterns.

PURPOSE: The purpose of the study was to evaluate the characteristics of sebaceous gland carcinoma (SGC) of the ocular adnexae, which is due to a high variability in clinical, histological and immunohistochemical characteristics often challenging to diagnose.

METHODS: Records of six patients with SGC were reviewed, who underwent surgical excision and who were histologically diagnosed with SGC. For comparison, there were specimens from four patients with basal cell carcinoma (BCC) and four patients with squamous cell carcinoma (SCC). Histological and immunohistochemical analysis included stains for HE, cytokeratins (CKpan, Cam5.2), epithelial membrane antigen (EMA), androgen receptor (AR441), perforin and adipophilin.

RESULTS: SGC's were located in the upper (n = 2) or lower (n = 4) eyelid and were associated with various presenting clinical signs including chalazion-like lesions with pyogenic granuloma (n = 1), papillomatous conjunctival tumors (n = 3), a hyperkeratotic exophytic neoplasm (n = 1) and an ulcerating crusted lesion resembling chronic blepharitis (n = 1). The treatment was tumor resection, followed (if necessary) by adjuvant therapy with topical Mitomycin C (n = 2). Histologic characteristics included basophilic pleomorphic cells with vacuolated cytoplasm, prominent nucleoli, mitotic figures and in some cases pagetoid spread (n = 2). CKpan, EMA and Cam5.2 showed strong positive immunoreactivity in all specimens (SGC, BCC, SCC). Perforin immunostaining showed a varying, but overall weak, non-specific cytoplasmatic staining reaction in all lesions. AR441 positivity was noted with variable intensity in almost all lesions and in particular in pagetoid spread in contrast to non-tumor cells. Adipophilin showed an annular staining of lipid granules in immature sebaceous cells in SGC in contrast to a more granular staining pattern in BCC and SCC.

CONCLUSION: SGCs display a variety of clinical signs and may mimic many other lesions. Tumor resection, followed by histological and immunohistochemical analysis, leads to the diagnosis and initiation of the proper treatment regimen. Herein, immunohistochemistry showed an unequivocal profile in SGC and did not allow for an exact differentiation from BCC and SCC by immunohistochemical means only. An extended evaluation of HE stains remains essential. However, immunohistochemistry can make relevant contributions to the diagnosis of SGC, especially in cases of inconclusive histology, by positive staining for adipophilin in immature sebaceous cells or by AR441 labeling in cases of pagetoid spread.