<p>Plasma cell mucositis is a rare, idiopathic, multifocal, benign proliferative disorder affecting upper aerodigestive tract. It is a very rare condition and less than 50 cases reported in literature. A 62 years old female patient reported with complaints of oral discomfort, superficial erosive ulceration on the tongue, and burning sensation on eating food for last 2 years. Initially, Incisional biopsy of the involved mucosal area confirmed the diagnosis of well differentiated squamous cell carcinoma for which hemi-glossectomy was done. However histopathological examination submitted revealed a hyperplastic epithelium with a dense infiltrate of mature polyclonal plasma cells in the superficial layer of lamina propria, for which plasma cell mucositis was made a diagnosis. Plasma cell mucositis is a diagnosis of exclusion, to be differentiated from other infective, reactive, autoimmune, allergic and neoplastic disorders with plasma cell infiltrates. Management includes topical, intralesional, systemic corticosteroids and debulking procedures. Regular follow-up is essential due to the possibility of its clinical persistence and chances of malignant transformation.</p>