<unk> , also termed NK<unk>  enteropathy (NKCE), and a closely related disorder, lymphomatoid gastropathy (LG), are non-malignant diseases in which one type of lymphocyte, the<unk><unk> <unk>  (i.e. NK<unk> , proliferates excessively in the gastrointestinal tract (GI tract). This proliferation causes red, sore-like spots, raised lesions, erosions, and ulcers in the mucosal layer surrounding the GI tract lumen. Both disorders cause either no or only vague symptoms of GI tract disturbances such as nausea, vomiting, and bleeding. In 2006, a persistent but apparently benign disease that involved the proliferation of NK<unk> s at multiple sites throughout the intestines was described. This disorder appeared similar to and easily mistaken for a highly malignant disease, extranodal NK/T-cell lymphoma, nasal type. In 2010, a similarly non-malignant disorder that involved the proliferation of NK<unk> s in the stomach was described. The disease mimicked gastrointestinal lymphomas. Since these first descriptions, several case series and case reports have been published on these enteropathies. The two NK<unk>  proliferation diseases have been termed NK<unk>  enteropathy and lymphomatoid gastropathy with NKCE being seen mostly in the United States and Korea and LG being seen mostly in Japan. Besides this geographical difference, the only other critical difference between the two diseases is that the lesions in NKCE occur in the small intestine, colon, stomach, and/or esophagus while those of LG are limited to the stomach. Since the pathophysiological features of the two diseases are virtually identical, NKCE and LG are now commonly viewed as manifestations of the same disease. Only 36 patients with NKCE or LG have been reported as of January 2019. Nonetheless, these diseases are emerging as important clinical entities because they 1) are newly described and likely to be diagnosed more often as they become better known and 2) have been mistaken for, and treated as, various types of pre-malignant and malignant lymphomas of the GI tract. Given the radical differences in the prognoses and treatments of NKCE and LG compared to the lymphomas that they can mimic, the evaluation of many lymphocyte-proliferating disorders of the GI tract must consider and rule out the possibility that they are NKCE or LG rather than a pre-malignant disorder or malignant lymphoma.
Natural killer cell enteropathy
Autoimmune enteropathy
Environmental enteropathy
Congenital tufting enteropathy
Food protein-induced enterocolitis syndrome
Tropical sprue
Coeliac disease
Schnitzler syndrome