Small Bowel Obstruction as an Initial Presentation of Mesenteric Follicular Lymphoma: Case Report and Literature Review.

Follicular lymphoma is the second most common type of B-cell non-Hodgkin lymphoma. It is known as one of the indolent lymphomas. Although some cases presenting with abdominal masses with or without symptoms have been reported, generally, primary extranodal follicular lymphoma is uncommon. Moreover, small bowel obstruction (SBO) as an initial presentation is extremely uncommon. We encountered a unique case of mesenteric follicular lymphoma that presented with SBO as the initial clinical presentation. A 61-year-old male presented with a three-day history of abdominal pain and recurrent vomiting. Abdominopelvic computed tomography revealed air-fluid levels in multiple small bowel loops, with a transition point associated with a mass-like mesenteric abnormality. The small bowel was resected, and a wedge resection was performed to relieve the obstruction and make a diagnosis. Histopathology and immunohistochemical staining confirmed the diagnosis of follicular B-cell lymphoma. Mesenteric lymphomas are less likely to present with SBO as the initial clinical presentation due to their extraluminal location. According to the literature review on the types of lymphomas that cause SBO, follicular lymphoma accounted for only 4.9% of lymphoma cases with SBO due to its indolent course.