Simultaneous occurrence of inflammatory bowel disease and myelodysplastic syndrome due to chromosomal abnormalities in bone marrow cells.

Background/aims: Although chromosomal abnormalities in bone marrow (BM) cells, such as trisomy 8, are risk factors for the development of inflammatory bowel diseases (IBD) as well as myelodysplastic syndrome (MDS), the mechanisms of how these cytogenetic abnormalities cause intestinal inflammation are poorly understood.

Methods And Results: A 55-year-old man with a 3-month history of watery diarrhea, fever and abdominal pain was admitted. Blood examinations revealed pancytopenia. Pathological analysis and endoscopic images of the entire colon led to the diagnosis of IBD of unclassified type. BM examination showed that the pancytopenia was due to MDS and that his BM cells had dual chromosomal abnormalities: 47, XY, +1, der(1;7)(q10;p10), +8. Immunological studies using peripheral blood monocytes from this patient revealed that the dual chromosomal abnormalities of BM cells led to the development of colitogenic monocytes producing a large amount of pro-inflammatory cytokines and showing resistance to apoptosis upon stimulation with microbial antigens.

Conclusion: An abnormal karyotype of BM cells is not only responsible for the development of MDS, but also for IBD in this case.