Primary giant mucosa-associated lymphoid tissue lymphoma of the lower lip: a case report and literature review.

Oral lymphomas are rare and difficult to diagnose, with Mucosa-Associated Lymphoid Tissue (MALT) lymphoma most commonly affecting older adults, particularly women. MALT lymphoma of the lip is exceptionally rare, and its cause is poorly understood. We present a case of primary giant MALT lymphoma of the lower lip, explore its clinicopathological features, and review relevant literature. An 83-year-old woman developed a painless, pea-sized swelling on the right lower lip over three years, which gradually increased in size without discomfort. She had no history of chronic infections or autoimmune diseases, and all investigations were unremarkable. Examination revealed a spherical, indurated mass on the left lower lip, measuring 8 cm, with no regional lymphadenopathy. Histology and immunohistochemistry confirmed extranodal marginal zone B-cell lymphoma of MALT. This case underscores the need to consider lymphoma in the differential diagnosis, even without systemic symptoms. Patients with oral MALT lymphoma often achieve complete remission after treatment, but diagnosing it can be challenging, requiring immunohistochemical testing for confirmation.