Figure 4d: Patient 5. Contrast-enhanced transverse CT scans in 42-year-old man without any known history of leukemia who presented with a palpable abdominal mass. (a) Initial CT scan shows jejunal lesion characterized by bowel wall thickening (black arrowheads) and an exophytic component (white arrowhead). There is also a soft-tissue mass (*) on mesenteric side of lumen that is continuous with primary lesion. This patient underwent surgical resection for suspected GI stromal tumor, and pathologic examination revealed granulocytic sarcoma. (b) CT scan at level of rectum shows soft-tissue mass (arrowheads) anterior to rectum in rectovescical pouch. Microscopic examination (results not shown) demonstrated leukemic cell infiltration of small bowel. (c, d) Follow-up CT scans obtained 2 months after a demonstrate worsening of leukemic dissemination with substantial omental (arrowheads in c) and mesenteric infiltration and rapid enlargement of the rectal soft-tissue mass (arrowheads in d). The patient did not receive any antileukemic treatment between the two CT examinations.