Granulocytic sarcoma of the rectum: a rare complication of myelodysplasia

A 67 year old man with myelodysplasia was admitted as an emergency with a s ix week history of rectal bleeding and diarrhoea. Barium enema showed an ir regular polypoid filling defect in the lateral wall of the proximal rectum near the rectosigmoid junction, Histology showed this to be a granulocytic sarcoma (extramedullary granulocytic leukaemia; chloroma) infiltrating the bowel. A low index of suspicion of this lesion results in an incorrect diag nosis in many such cases. A chloroacetate esterase immunoperoxidase stain w ill confirm the granulocytic nature of the tumour cells.