Autoimmune enteropathy associated with T cell large granular lymphocytic leukemia in a patient with BACH2 mutation: a...

T cell large granular lymphocytic leukemia (T-LGL) is a rare indolent lymphoproliferative disorder caused by aberrantly clonal expansion of cytotoxic T lymphocytes. Active mutations of STAT3 are the hallmark of this disease. It is commonly associated with autoimmune disorders involving multiple organ systems. However, its association with autoimmune enteropathy has been rarely reported.

A 36-year-old female had a history of T-LGL and multiple autoimmune disorders, including type I diabetes mellitus, pure red cell aplasia, IgA deficiency, celiac disease and recurrent infection and bacteremia. She carries an HLA-DQ8 allele and a germline heterozygous mutation of BACH2. Bone marrow biopsy demonstrated T-LGL involvement. She presented with chronic diarrhea. Laboratory tests for viral and bacterial infections were negative. Colonoscopy showed diffuse edema with loss of vascular markings in the entire colon. Microscopically, absence of goblet cells and Paneth cells, as well as intraepithelial lymphocytosis and prominent crypt apoptosis, was present. Serology for an anti-enterocyte antibody was positive. A diagnosis of autoimmune enteropathy was made.

We report an extremely rare case of autoimmune enteropathy associated T-LGL in a patient with non-STAT gene mutations. Further investigation of the functional changes and pathogenesis of the co-existent BACH2 mutation in this clinical setting is warranted.