Macrocytosis in Crohn's disease: a devastating blast.
A 47-year-old woman with a 36-month history of Crohn's disease with one previous bowel resection treated with azathioprine was found to have a persistently raised mean corpuscular volume (MCV) on routine complete blood count testing. Despite vitamin B12 replacement, her MCV remained elevated. A bone marrow biopsy was performed, which demonstrated myelodysplastic syndrome. Macrocytosis is a common abnormality in patients with Crohn's disease, most commonly due to vitamin B12 deficiency and secondarily due to bacterial overgrowth. However, it is important to recognise that myelodysplastic syndrome is a common under-reported complication of azathioprine therapy. One-third of cases progress to acute myeloid leukaemia with poor prognosis. In patients with suspected myelodysplastic syndrome, azathioprine therapy should be immediately discontinued.
Department of Gastroenterology, Milton Keynes NHS Foundation Trust, Milton Keynes, UK. lennardywlee@gmail.com
Lennard Y W
LY
Lee
Vidya
V
Santharam
George
G
Macfaul
D003424:Crohn Disease / Q000150:complications*; D004913:Erythrocytes, Abnormal; D005260:Female; D006801:Humans; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000209:etiology*