MegaAppendix: a rare case of mantle cell lymphoma in an appendix presented as volvulus.

Mantle cell lymphoma (MCL), representing 5% of cases, is an aggressive B-cell non-Hodgkin lymphoma. Rarely, it can spread to other areas. This case illustrates a unique occurrence of MCL involving the appendix, leading to obstructive symptoms. Additionally, its presentation as volvulus added complexity to diagnosis and treatment. A 72-year-old man with a history of MCL came to the ER with right lower quadrant abdominal pain and nausea for 7 days. A computed tomography scan showed a swirling sign, concerning for volvulus. The patient required emergent surgery for exploratory laparotomy. Intraoperatively, the patient was found to have an enlarged appendix measuring 16.5 cm in length and 5 cm in diameter. An appendectomy was performed, and the pathology was confirmed to be MCL. This is a rare case of MCL presenting in the appendix as a volvulus, resulting in obstructive symptoms. This distinctive manifestation posed significant challenges in diagnosis and management. Appreciating such cases is pivotal for accurate diagnosis and effective medical and surgical interventions for this aggressive lymphoma subtype.