Abstract
OBJECTIVES: Primary intestinal T-cell and natural killer-cell lymphomas (PITNKLs) are aggressive and make pathologic diagnoses in biopsy specimens challenging. We analyzed different subtypes' clinicopathologic features and treatment outcomes. METHODS: Seventy-nine PITNKL cases were characterized by clinical, morphologic, and immunohistochemical features. RESULTS: Among 79 cases of PITNKLs from 2008 to 2017 in our institution, 40 (50.63%) were extranodal NK/T-cell lymphoma, nasal type (ENKTL); 32 (40.51%) monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL); 6 (7.59%) intestinal T-cell lymphoma, not otherwise specified; and 1 (1.27%) indolent T-cell lymphoma of the gastrointestinal tract. Small intestine (n = 47) was the most common site. Monomorphic epitheliotropic intestinal T-cell lymphoma showed distinctive clinicopathologic features from other subtypes with high expression (96.88%) of spleen tyrosine kinase (SYK) and PD-L1 (87.5%) and the poorest prognosis (P < .001). CD30 was highly expressed in ENKTL (9/17, 57.94%) and irrelevant to prognosis (P > .05). CONCLUSIONS: Cases of PITNKL are biologically heterogeneous; most have a dismal prognosis. SYK and PD-L1 expression might be a significant marker for MEITL and helps differential diagnosis.