Abstract:
Incidental PET demonstration of abnormal focal F-18 FDG accumulation within the colon may be related to benign, precancerous, or malignant tumors. This pattern of uptake should prompt colonoscopic evaluation and tissue sampling of eventual colonic lesion. The author reports a case of simultaneous PET finding of a hyperplastic polyp and a tubulovillous adenoma during lung cancer evaluation.
Key Words: positron emission tomography, colon, hyperplastic polyp, tubulovillous adenoma
(Clin Nucl Med 2005;30: 48–50)

REFERENCES
1. Zhuang H, Hickeson M, Chacko TK, et al. Incidental detection of colon cancer by FDG positron emission tomography in patients examined for pulmonary nodules. Clin Nucl Med. 2002;27:628.
2. Chen YK, Kao CH, Liao AC, et al. Colorectal cancer screening in asymptomatic adults: the role of FDG PET scan. Anticancer Res. 2003; 23:4357– 4361.
3. Patrikeos AP, Mackay JR, Hicks RJ. Detection of synchronous adenocarcinomas and multiple dysplastic polyps with F-18 FDG positron emission tomography in a case of nonfamilial polyposis. Clin Nucl Med. 2003;28:487– 488.
4. Drenth JP, Nagengast FM, Oyen WJ. Evaluation of (pre-) malignant colonic abnormalities: endoscopic validation of FDG-PET findings. Eur J Nucl Med. 2001;28:1766.
5. Yasuda S, Fujii H, Nakahara T, et al. 18F-FDG PET detection of colonic adenomas. J Nucl Med. 2001;42:989.
6. Tatlidil R, Jadvar H, Bading JR, et al. Incidental colonic fluorodeoxyglucose uptake: correlation with colonoscopic and histopathologic findings. Radiology. 2002;224:783.
7. Pin CA, Grigolon MV, Etchebehere EC. Detection of synchronous carcinomas of the colon with F-18 fluorodeoxyglucose: a case report. Clin Nucl Med. 2000;25:370 –371.
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Received for publication January 14, 2004; accepted March 18, 2004.
From the Department of Radiology, Mayo Clinic Scottsdale, Arizona.
Reprints: Ba D. Nguyen, MD, Department of Radiology, Mayo Clinic Scottsdale, 13400 E. Shea Boulevard, Scottsdale, AZ 85259. E-mail: nguyen.ba@mayo.edu
Copyright © 2004 by Lippincott Williams & Wilkins
ISSN: 0363-9762/05/3001-0048
48 Clinical Nuclear Medicine • Volume 30, Number 1, January 2005

FIGURE 1.
An 82-year-old woman underwent F-18 FDG PET imaging to evaluate a 1.5-cm right upper lobe nodule detected by chest CT. The PET study showed no right pulmonary abnormal radiotracer uptake in the right lung, ruling out the presence of a high metabolic neoplasm. There were, however, 2 foci of radiotracer accumulation within the proximal ascending colon (arrow) and transverse colon (open arrow) suspicious for metabolically active lesions.
Clinical Nuclear Medicine • Volume 30, Number 1, January 2005 Concomitant Colonic Polyp and Adenoma
© 2004 Lippincott Williams & Wilkins 49
FIGURE 2.
(A, B) Subsequent abdominal and pelvic CT examination showed 2 polypoid masses near the cecum (A, arrow) and within the proximal transverse colon (B, curved arrow) measuring 18 mm and 13 mm in greatest dimension respectively. Colonoscopy confirmed the 2 lesions seen on PET and CT. Their resection diagnosed a hyperplastic polyp in the transverse colon and a tubulovillous adenoma in the cecum.

PET imaging in an older patient population for evaluation of pulmonary malignancy may show unexpected abnormal focal FDG F-18 accumulation within the colon. This same patient population is at high risk of colon neoplasm and needs further workup for these focal colonic PET findings.1 Premalignant colonic lesions such as villous and tubulovillous adenomas have been reported with PET.2,3 Their detection is related to their size (
1.3 cm) and preferential locations at the less mobile segments of the colon.1,4,5 Recently, hyperplastic polyps, usually considered as benign and nonneoplastic lesions of the colon, have been reported as additional causes of focal colonic FDG uptake.6 Contrary to the diffuse pattern of FDG accumulation in the colon, which is mostly benign and physiologic, focal radiotracer colonic uptake on PET imaging shows a predictive value greater than 74% for positive pathologic findings represented by hyperplastic polyps, adenomas, and adenocarcinoma on subsequent colonoscopic evaluation and tissue biopsy.4,6–8
Nguyen Clinical Nuclear Medicine • Volume 30, Number 1, January 2005
50 © 2004 Lippincott Williams & Wilkins

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