Sebaceous adenocarcinomas of the major salivary glands: a clinicopathological analysis of 10 cases

AIMS: Sebaceous carcinomas are uncommon malignant cutaneous tumours originating from the pilosebaceous unit. Although its occurrence is mostly common in peri-ocular glands, other anatomical regions of the head and neck may be affected, including major and minor salivary glands. METHODS AND RESULTS: We describe a series of sebaceous adenocarcinomas of the parotid and submandibular glands. The mean age was 62.1 (range = 31-90) years. Two patients (20%) presented regional or distant metastasis to mandible and lungs. All cases were positive for cytokeratins (AE1AE3 and CK-5), epithelial membrane antigen and adipophilin and negative for androgen receptor, Factor XIIIa, S-100, vimentin and perforin. MLH1 and MSH2 were expressed in the nuclei of most tumour cells, and one case showed loss of MSH2 expression. Proliferative index (assessed by Ki-67 expression) and microvessel density (CD34-positive vessels) were higher in metastasis-associated cases. P63 expression was noted in the periphery of the tumour nests, in the basaloid cells, with a mean of 69.2% nuclear positivity. CONCLUSIONS: The sebaceous adenocarcinoma of salivary glands is rare and may show an unfavourable outcome; therefore, its correct diagnosis may be challenging. For this reason, immunohistochemical studies, including adipophilin in particular, constitute an important diagnostic tool.