Circumorificial plasmacytosis (CP; also known as plasma cell orificial mucositis and plasma cell mucositis) is a rare, benign plasma cell disorder of the oral cavity. It commonly affects the gingivae and buccal mucosa, but any intraoral surface may be affected. It has occasionally been reported to involve the lower lip, oral commissures, larynx, and trachea.

CP presents as one or more erythematous mucosal plaque(s) with a cobblestoned, velvety, nodular, or papillomatous appearance. While CP can be asymptomatic, oral pain, swelling, dysphagia, hoarseness, and stridor have been reported. Secondary erosions may occur.

The etiology of CP is unknown, although patients with CP may have a history of autoimmune disease and/or atopy. CP has been reported to occur in a wide age range, but it most commonly occurs in patients older than 50 years.