An association was suggested to exist between the myelodysplastic syndromes and Crohn disease on the basis of concomitant finding of these disorders in a series of four patients [1]. Three of these patients had clonal abnormalities of chromosome 20 in the bone marrow cells. The potential role of immune dysfunction as a common pathogenetic factor of the myelodysplastic syndromes and inflammatory bowel disease was also discussed.

We describe a 70-year-old man with a 20-year history of irritable bowel disease who presented with signs of a hematologic disorder. Symptoms of irritable bowel disease were mild until October 1991, when the patient had frequent diarrhea. In July 1992, he presented with anemia (hemoglobin level, 6.7 g/dL), leukopenia (leukocyte count, 3.9 x 10⁹/L), and thrombocytopenia (platelet count, 117 x 10⁹/L). A bone marrow smear showed increased erythropoiesis with megaloblastic and dyserythropoietic characteristics and was consistent with a diagnosis of refractory anemia (myelodysplastic syndrome type 1) or, alternatively, reactive changes [2]. The patient's folate and vitamin B₁₂ levels were normal. Treatment with corticosteroids was begun. A colonoscopy done in December 1992 showed segmentally distributed inflammatory changes of the descending and sigmoid colon, compatible with a diagnosis of Crohn disease. The leukocyte and platelet counts decreased to 1.1 x 10⁹/L and 13 x 10⁹/L, respectively. A second bone marrow smear showed 25% dysplastic erythropoiesis with 30% ringed sideroblasts. Twenty-five percent immature myeloid cells was present, compatible with a diagnosis of myelodysplastic syndrome type 5 [2]. Cytogenetic analysis of bone marrow cells showed no clonal abnormalities, but such findings are absent in about 50% of cases of the myelodysplastic syndrome [3]. The patient died in February 1993.

The myelodysplastic syndromes are rare [4] and usually develop in patients older than age 60 years. Crohn disease is typically diagnosed in younger persons, with a suggested second peak after 60 years [5]. Although the association between the myelodysplastic syndrome and Crohn disease might be coincidental, further support of a potential susceptibility to the development of the syndrome in patients with Crohn disease should be systematically sought. Meanwhile, the possibility of the myelodysplastic syndrome should be considered in patients with Crohn disease who develop cytopenias.