Positron emission tomography computed tomography features of monomorphic epitheliotropic intestinal T-cell lymphoma

Objective: To define the positron emission tomography/computed tomography (PET/CT) features of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), a rare malignancy in European and North American populations and the most common form of primary intestinal T-cell lymphoma in Asian populations. Methods: F-18-fluorodeoxyglucose (FDG) PET/CT findings of a cohort of MEITL patients were retrospectively analyzed. Results: Eight men and four women with MEITL investigated by PET/CT at diagnosis and relapse were retrospectively analyzed. On presentation, the primary involved sites were the small bowel (N = 8), large bowel (N = 2), stomach (N = 1) and small and large bowels (N = 1). The uninvolved small bowel did not show increased FDG-avidity to suggest enteropathy. On presentation, lymph nodes and other organs were involved in seven cases (58%). The primary lesions were hypermetabolic except in one case, where the colonic lesion was eumetabolic. At relapse, the stomach and large bowel might be involved even if the primary tumours arose from the small bowel, and multiple extra-intestinal metastases occurred. Interestingly, thoracic structures and the brain were frequently involved (50% and 25% respectively). Conclusion: These findings showed that in contrast to classical enteropathy-associated T-cell lymphoma, where the small bowel is the exclusive primary site (owing to its origin from coeliac disease) and distant metastases even during relapse are exceptional, MEITL might on presentation and during relapse involve any part of the gut, and metastasize to multiple extra-intestinal sites.