Sebaceous carcinoma of the lip: a case report and review of the literature.

Background: Sebaceous carcinoma is a very rare, aggressive, malignant tumor arising in the adnexal epithelium of the sebaceous gland. Sebaceous carcinoma in the oral cavity is extremely rare, with only 14 cases reported in literature. We reported the fourth case of sebaceous carcinoma involving the lip CASE PRESENTATION: A 71-year-old Caucasian male smoker presented an ulcerated lesion in the lateral region of the lower lip. The patient stated that the lesion had been present for 1 year. The past medical history was unremarkable. Extraoral examination revealed a markedly ulcerated, exophytic, irregularly shaped, indurated mass of the lower right labial region, measuring 1.8 cm in size. The nodular lesion, located at the point of transition between mucosa and skin, showed a central ulceration. No other intraoral lesions were identified. The clinical differential diagnosis included squamous cell carcinoma, basal cell carcinoma with sebaceous differentiation, and salivary gland neoplasms. Operation was performed under local anesthesia. On histopathological examination, the tumor was composed by nodules or sheet of cells separated by a fibrovascular stroma. The neoplastic tissue was deeply infiltrating, involving the submucosa and even the underlying muscle. Neoplastic cells showed a range of sebaceous differentiation with finely vacuolated rather than clear cytoplasm. Neoplastic cells were positive for S-100 protein and epithelial membrane antigen, but negative for carcinoembryonic antigen. Based on these findings, a diagnosis of sebaceous carcinoma of the lower lip was rendered.

Conclusion: The histogenesis, differential diagnosis, and clinicopathological conditions of this disease according to literature are reviewed. Sebaceous carcinoma should be distinguished from other tumors full of vacuolated clear cells. A periodic acid-Schiff stain and immunohistochemical stain for Ki-67, P53, cytokeratin, S-100, epithelial membrane antigen, and androgen receptor can be useful for the diagnosis.