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A 37-year-old woman was referred by her gynecologist for evaluation of a newly discovered rectal mass. She reported difficulty moving her bowels and a pelvic heaviness, “like a ball in her pelvis.” This sensation was relieved by defecation. She had no blood throughout the rectum. Earlier in the year she was evaluated for infertility and diagnosed with uterine fibroid tumors. She was taken to the operating room for excision of the fibroids. Intraoperatively, a large, fixed mass was discovered in her pelvis between the rectum and the vagina. No biopsies were taken during the procedure. Her medical history was not contributory. She had no family history of colorectal cancer. Results of abdominal examination were unremarkable. Digital rectal examination revealed a fixed mass in the anterior rectum approximately 7 cm from the anal verge.
Sigmoidoscopy revealed a 3-cm submucosal mass with small mucosal ulcerations. Endoscopic biopsies revealed epithelial changes, with no malignancy. Results of laboratory testing for carcinoembryonic antigen revealed a level of less than 0.4 ng/mL (to convert to micrograms per liter, multiply by 1.0).
Pelvic T2-weighted magnetic resonance imaging revealed a heterogenous mass extending from the rectal mucosa through the mesorectum. It arose from the right lateral wall of the rectum and measured 3.9 × 3.3 cm (Figure 1). Positron emission tomography–computed tomography showed mild to moderate fludeoxyglucose activity in the anterior rectal wall mass (Figure 2).
Figure 1. Axial T-2 weighted magnetic resonance imaging scan of the pelvic area indicates multiple low–T2 signal masses (white arrows) in the uterus compatible with fibroids. The rectum is also identified (black arrow).
Figure 2. An axial positron emission tomographic scan of the pelvic area demonstrated a mild to moderately fludeoxyglucose-avid rectal mass (white arrows). Intensely fludeoxyglucose-avid foci are noted anterolaterally and posteromedial to the uterus. The rectum is also identified (black arrow).
What Is the Diagnosis?
A. Adenocarcinoma of the rectum
B. Gastrointestinal stromal tumor
D. Neuroendocrine tumor
Maxey D, Wick EC, Gearhart S. Image of the Month—Quiz Case. Arch Surg. 2010;145(3):305. doi:10.1001/archsurg.2010.11-a
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