Monomorphic epitheliotropic intestinal T cell lymphoma

Monomorphic epitheliotropic intestinal T cell lymphoma (MEITL) (formerly termed enteropathy-associated T cell lymphoma, type II) is an extremely rare peripheral T-cell lymphoma that involves the malignant proliferation of a type of lymphocyte, the T cell, in the gastrointestinal tract (i.e. GI tract). Over time, these T cells commonly spread throughout the mucosal lining of a portion of the GI tract (particularly the jejunum and ileum of the small intestine), lead to GI tract nodules and ulcerations, and cause symptoms such as abdominal pain, weight loss, diarrhea, obstruction, bleeding, and/or perforation.

In 2008, the World Health Organization defined a specific type of lymphoma, enteropathy-associated T cell lymphoma (EATL), as having two different types: EATL type I, a lymphoma occurring in patients with the chronic, autoimmune GI tract disorder, celiac disease, and EATL type II, a similar bowel lymphoma that was not associated with celiac disease. However, subsequent studies found significant clinical, pathologic, and pathophysiological differences between these two types of lymphoma. Consequently, the World Health Organization (2016) redefined these lymphomas as separate entities, terming the celiac disease-associated lymphoma as enteropathy-associated T cell lymphoma (EATL) and the lymphoma not associated with celiac disease as monomorphic epitheliotropic intestinal T cell lymphoma (MEITL). MEITL is only 1/5 to 1/10 as common as EATL. The Organization (2016) also termed a third type of intestinal T cell lymphoma that could not be classified as ATL or MEITL as intestinal T cell lymphoma, not otherwise specified.

MEITL is a highly aggressive GI tract lymphoma which typically has had very short survival times following its diagnosis. The disease often occurs in elderly patients who are afflicted with other ailments and consequently have little tolerance for the standard chemotherapy regimens that are used to treat other types of lymphomas. Moreover, these therapeutic regimens have shown little effectiveness in treating MEITL. To date, the best but still only marginally effective therapeutic interventions for the disease have been treatments that incorporate hematopoietic stem cell transplantation into chemotherapy plus surgical (when needed to treat local bowel issues such as obstruction or perforation) regimens.