Mucosa-Associated Lymphoid Tissue Lymphoma Affecting the Accessory Parotid Gland in Sjogren Syndrome: Case Report and Immunohistochemical Analysis

Mucosa-associated lymphoid tissue (MALT) lymphoma is a subtype of non-Hodgkin lymphoma, often described as affecting the parotid glands (PGs) in Sjogren syndrome (SS). Accessory parotid gland (APG) represents ectopic salivary tissue distant and separate from the main PG, observed in 21% to 61% of the general population. The incidence of PG tumors is more common in APG than in PG; however, APG lymphoma is a rare condition. A 30-year-old woman with a diagnosis of primary SS was referred, presenting with a nodule in the buccal mucosa, with 1 month of evolution. Histopathologic examination showed atypical lymphoid proliferation and plasma cells, germinal centers and lymphoepithelial lesions, supported by typical PG parenchyma. Immunohistochemistry revealed positivity for CD45, CD20, bcl-2, and kappa light chain restriction. Ki-67 labeling index was less than 5%. APG tumors are clinically rare but should be considered in the differential diagnosis of a mid-cheek mass, especially in SS.