[Extranodal nasal type natural killer/T-cell lymphoma of the digestive system: a clinicopathological study of...

Objective: To investigate the clinicopathological features, and diagnostic and differential diagnostic characteristics of extranodal nasal type natural killer/T-cell lymphoma (ENKTCL) of the digestive system. Methods: Thirteen cases of ENKTCL in the digestive system were collected at the Henan Provincial People's Hospital, Zhengzhou, China, from August 2000 to August 2020. The histopathological, immunohistochemical and in situ hybridization features were analyzed, as well as those of T-cell receptor (TCR) gene rearrangement in some cases. The patients were followed up. Results: There were 11 males and 2 females. The age ranged from 28 to 80 years (median=53 years). Seven cases were present in the colorectum, and 3 cases were present in the small intestine. The other three cases were in stomach, gallbladder and liver (one case each). The main clinical symptoms were fever, and abdominal pain, often accompanied by fatigue, diarrhea, hematochezia, elevated serum albumin, elevated lactate dehydrogenase, and increased peripheral blood EB virus DNA copy. Histologically, the tumor accompanied by a heavy admixture of inflammatory cells (small lymphocytes, plasma cells and histiocytes). There was diffuse dense tumor cell infiltrate, with prominent coagulative necrosis. The lymphomatous infiltrate had angiocentric and angio-necrotic changes. Immunohistochemically, lymphoid cells expressed CD3 in all cases. Some of them showed weakened/absent other T cell markers, while all of them expressed CD56 except 1 case. A few of the cases showed CD4^-/CD8⁺ killer T cell phenotypes. In situ hybridization showed EB virus encoded RNA (EBER) was positive in all cases. Clonal TCR gene rearrangement was not detected in all 7 cases tested. The median survival time was 9 months. Conclusions: ENKTCL of the digestive system is extremely rare. It often predisposes the patients to acute abdomen such as perforation of the gastrointestinal tract. The treatment outcomes are dismal, and the prognosis is poor. Clinical and imaging studies are often non-specific. It is also easy to be misdiagnosed as non-specific ulcers. Combined with immunohistochemistry, in situ hybridization and TCR gene rearrangement analysis and better understanding of this tumor's clinicopathological characteristics can help improve its diagnosis and early treatment.