Arch Pathol Lab Med—Vol 125, May 2001 Pathologic Quiz Case—Resetkova et al 703 Pathologic Quiz Case A Pelvic Mass With Abdominal Dissemination Erika Resetkova, MD, PhD; Anthony Padula, MD; Syed A. Hoda, MD A 55-year-old African American man with no significant past medical history presented to our emergency de- partment with a 9-kg (20-lb) weight loss, upper gastro- intestinal discomfort, and abdominal protuberance of 3 months’ duration. The patient denied smoking, alcohol use, and drug abuse. He had been employed as a house painter for about 20 years. Physical examination revealed a distended abdomen with a palpable mass in the right lower quadrant. There were no signs of peritonitis or ascites. Initial laboratory values included a white blood cell count of 13  10 9 /L (reference range, 4.5–11  10 9 /L) with a normal differ- ential, a hemoglobin level of 119 g/L (reference range, 135–180 g/L), a platelet count of 539  10 9 /L (reference range, 150–450  10 9 /L), and a lactate dehydrogenase val- ue of 412 U/L (reference range, 100–190 U/L). All other chemistry values were within reference ranges. Colonos- copy showed no mucosal lesions, but the mucosa was seemingly undermined by numerous bulging masses. Accepted for publication August 15, 2000. From the Departments of Pathology, New York Presbyterian–Weill Cornell Center, New York, NY (Drs Resetkova and Hoda); and State University of New York Downstate, Brooklyn, NY (Dr Padula). Reprints not available from the author. Computed tomography with contrast showed a large, poorly defined pelvic mass at the level of the sigmoid co- lon, narrowing of the colonic lumen, and extensive thick- ening of the mesentery and omentum (Figure 1). Fine- needle aspiration biopsy revealed malignant cells sugges- tive of adenocarcinoma. Rapid deterioration in the pa- tient’s physical condition was marked by fever, tachypnea, tachycardia, and finally by cardiac arrest. At autopsy, a 14  12  10-cm, poorly circumscribed, tan, fleshy pelvic mass located posterior to the bladder and encasing loops of small and large bowel was found. The peritoneal surfaces of the viscera, omentum, and mes- entery, as well as both sides of the diaphragm, were stud- ded by numerous tan, firm nodules (0.5–3.0 cm) (Figure 2). Microscopically, pleomorphic spindle cells in a vaguely storiform pattern amid fibrous stroma were seen invading adjacent adipose tissue (Figure 3). Tumor cells demon- strated diffuse, strongly positive immunoreactivity for cy- tokeratins (AE1/3 and CK7), epithelial membrane antigen, vimentin, and calretinin. The pattern of staining with cal- retinin was cytoplasmic and finely granular (Figure 4). Im- munohistochemical staining for Ber-EP4, B72.3, carci- noembryonic antigen, c-kit, desmin, Leu-M1, muscle-spe- cific antigen, and S100 protein was negative. What is your diagnosis?