Anaplastic Large-cell Lymphoma Involving Gastrointestinal Tract: A Clinicopathologic Study of 25 Cases of a Rare Tumor at a Rare Site.

Anaplastic large-cell lymphoma (ALCL) is an uncommon lymphoma divided into anaplastic lymphoma kinase (ALK) positive, ALK negative, and breast implant-associated (BIA) ALCL. Gastrointestinal tract involvement is very rare and may be difficult to diagnose. Its recognition is crucial as prognostic ramifications are different. To describe clinicopathological features of ALCL involving the gastrointestinal tract. Slides were reviewed. Diagnosis was confirmed. Histological and immunohistochemical features were described. Twenty-five tumors were diagnosed during the study period. Ages ranged from 14 to 65 years (mean 41 years). Mean age for ALK-negative and ALK-positive patients were 49 and 17 years, respectively. Twenty-one were males and 4 were females. Eighteen involved small intestine. Mean tumor size was 4.2 cm. All showed diffuse sheets of large anaplastic cells with pleomorphic nuclei, abundant pink cytoplasm, and strong positivity for CD30. Epithelial membrane antigen was positive in 17 tumors and keratin was negative in all. Eighteen tumors were ALK negative. Out of 14 patients with follow-up, 12 died within a few months of diagnosis. Seven had stage IE, 5 had stage IIE, and 2 had stage IV disease. Two patients were alive at 35 and 60 months. Twelve received chemotherapy. A marked male predominance was noted. Small intestine was the commonest site of involvement. Majority were ALK negative. ALK-negative tumors occurred in older patients and ALK positive in younger patients. Prognosis was poor. ALCL should be included in the differential diagnosis of anaplastic epithelioid cell neoplasms in the gastrointestinal tract.