Hemorrhoids: A Possible Cause of High FDG Uptake in the Rectum

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1 Hemorrhoids: A Possible Cause of High FDG Uptake in the Rectum Yu-Yu Lu, Wan-Yu Lin Department of Nuclear Medicine, Taichung Veterans General Hospital, Taichung, Taiwan A 52-year-old man underwent 18 F-FDG positron emission tomography (FDG PET) scan as part of a physical check-up. FDG PET scan revealed a focal high uptake in the rectum at 1 hr after injection of FDG. Delayed 3-h imaging was performed after enema and it showed no change in the lesion. The diagnosis of this lesion was internal hemorrhoids based on sigmoidoscopy. After a 6-month-follow-up, the patient was doing well. To our knowledge, the high level of FDG uptake in a hemorrhoid has not yet been reported. Key words: hemorrhoid, FDG-PET, false positive, rectum Case Report A 52 year-old male with no history of colorectal or other cancer received a FDG PET scan for tumor screening. The PET images showed an FDG-avid region in the rectum with a maximum standard uptake value (SUV) of 8.0 at 1 h after injection of FDG. After enema with 20 ml of 15% sodium chloride and 0.001% 3-methyl-6-isopropylphenol, delayed 3-h imaging was performed and it revealed no change in the lesion. The maximum SUV slightly increased to 8.1. Rectal malignancy was suspected [8-12]. A sigmoidoscopy was performed and it showed only internal hemorrhoids in the rectum [13,14]. After clinically following up for 6 months, there was no evidence of malignancy. Ann Nucl Med Sci 2006;19: Introduction Whole body 18 F-fluorodeoxyglucose positron emission tomography (FDG PET) scan is widely used in the evaluation of malignant tumors and multiple reports have shown that increased FDG uptake is present in nonmalignant lesions, such as benign tumors, inflammation [1-5] or thrombotic lesions [6,7]. However, to our knowledge, FDG activity in hemorrhoids has not yet been described. We present here a case of hemorrhoids with positive uptake of FDG on PET. Received 6/22/2006; revised 6/27/2006; accepted 7/4/2006. For correspondence or reprints contact: Wan-Yu Lin, MD, Department of Nuclear Medicine, Taichung Veterans General Hospital. 160 Section 3, Taichung Harbor Road, Taichung 407, Taiwan. Tel: (886) , Fax: (886) , wylin@vghtc.vghtc.gov.tw Discussion Hemorrhoids are one of the most common conditions and they frequently affect the adult population. The main observations of hemorrhoids are hemorrhage, thrombosis and prolapse. Various factors have been shown to contribute to the development of hemorrhoids. Previous studies have proposed that the mechanisms of hemorrhoidal development are: the varicose vein theory, the sliding anal-lining theory, the vascular hyperplasia theory [15] and the neovascularization theory [16]. These pathological changes result in prolapsed anovascular cushions, and subsequently an impaired venous return occurs. The impaired venous return induces dilation of the venous plexus, venous stasis and/or thrombosis [17]. Thrombosis in the venous plexus may elicit an inflammatory response. Moreover, the vascular proliferation has been reported as an important pathologic change in hemorrhoids, which might be due to thrombosis formation [17]. Therefore, thrombosis, inflammation, and vascular proliferation should

2 Lu YY et al be considered in the pathogenesis of hemorrhoids. Whole body FDG PET scan is a powerful imaging modality in the evaluation of malignancies. Malignant cells exhibit higher glucose metabolism than normal cells, which results in a high uptake of FDG in malignancy. In addition, high FDG uptake has also been documented with nonmalignant lesions. Benign tumors, thrombotic lesions, inflammation or neovascularization [1-7,18-20] may also increase glucose metabolism in cells. To the best of our knowledge, this is the first case reporting a high FDG uptake in a hemorrhoid. This patient did not have any history of colorectal or other cancer. The only symptom in this patient was bleeding on wiping after defecation with a condition such as overstraining. The exact cause of high FDG uptake in this patient remains unclear. We considered thrombosis and inflammation, and vascular proliferation may have contributed to the high FDG uptake in this case. Peeyuch et al. [6] reported a focal FDG activity at the distal end of the intravenous catheter due to catheter-related thrombosis when radiotracer was injected through a peripheral vein instead of the central venous catheter, which was used in this study. The maximum SUVs of FDG activity in 3 patients with final diagnosis of catheter-related thrombosis were 9.5, 4.4, and 5.0, respectively, in their study. The authors concluded that thrombosis and inflammation are the reasons for increased FDG uptake. FDG PET scan gives rise to radioactivity accumulation one-hour image coronary view transverse view sagittal view three-hour image coronary view transverse view sagittal view Figure 1. The patient fasted for over 8 h before the PET examination. The upper row images obtained 1 h after intravenous injection of 370 MBq of 18 F-FDG using a dedicated PET scanner (Siemens Ecat Exact HR plus, Knoxville, TN, USA) show an area of increased FDG uptake (about cm in size) in the rectum (arrows). The maximum SUV of the lesion was 8.0. In order to exclude the interference from normal bowel activity, an enema with 40 ml of 15% sodium chloride and 0.001% 3- methyl-6-isopropylphenol was administered. On the delayed scanning performed 3 h after the 18 F-FDG injection (the lower row images), the FDG-avid region remains noted in the rectum with a maximum SUV of 8.1 (arrows). Malignancy was suspected based on the FDG PET scan. A sigmoidoscopy was performed and internal hemorrhoid of the rectum was the final diagnosis. Ann Nucl Med Sci 2006;19: Vol. 19 No. 3 September

3 -18-FDG High FDG uptake in hemorrhoid in the colon. It is very difficult to distinguish physiologic from pathologic uptake in the intestine sometimes. High FDG uptake in the colon on PET scan tends to be considered as a malignancy. However, normal bowel activity can have high FDG uptake as well. Few studies found that colonic artifacts can be eliminated by cleansing the colon with an isosmotic solution [21,22]. In this case, a high FDG-avid lesion was suspected in the rectum. An enema with 20 ml of 15% sodium chloride and 0.001% 3-methyl-6-isopropylphenol was performed in order to get rid of the interference from physiologic FDG uptake. However, the FDG-avid lesion remained in the rectum after the enema and defecation and the intensity of FDG uptake in the lesion even slightly increased from 8.0 to 8.1, indicating a pathologic uptake rather than normal bowel activity. In conclusion, persistent high FDG uptake in the rectum may not always indicate a malignancy. We suggest that hemorrhoids should be considered as one possible cause of focal high FDG uptake in the rectum. References 1. Zhuang H, Alavi A. 18-flurodeoxyglucose positron emission tomographic imaging in the detection and monitoring of infection and inflammation. Semin Nucl Med 2002;32: Cook GJ, Fogelman I, Maisey MN. Normal physiologic and benign pathological variants of 18-fluoro-2- deoxyglucose positron emission tomography scanning: potential for error in interpretation. Semin Nucl Med 1996;26: Kostakoglu L, Hardoff R, Mirtcheva R, Goldsmith SJ. PET-CT fusion imaging in differentiating physiologic from pathologic FDG uptake. Radiographics 2004;24: Shreve PD, Anzai Y, Wahl RL. Pitfalls in oncologic diagnosis with FDG PET imaging: physiologic and benign variants. Radiographics 1999;19: Zhuang H, Yu JQ, Alavi A. Applications of fluorodeoxyglucose-pet imaging in the detection of infection and inflammation and other benign disorders. Radiol Clin North Am 2005;43: Bhargava P, Kumar R, Zhuang H, Charron M, Alavi A. Catheter-related focal FDG activity on whole body PET imaging. Clin Nucl Med 2004;29: Chang KJ, Zhuang H, Alavi A. Detection of chronic recurrent lower extremity deep venous thrombosis on fluorine-18 fluorodeoxyglucose positron emission tomography. Clin Nucl Med 2000; 25: Guillem JG, Moore HG, Akhurst T, et al. Sequential preoperative fluorodeoxyglucose-positron emission tomography assessment of response to preoperative chemoradiation: a means for determining long-term outcomes of rectal cancer. J Am Coll Surg 2004;199: Longo WE, Johnson FE. The preoperative assessment and postoperative surveillance of patients with colon and rectal cancer. Surg Clin North Am 2002;82: Takeuchi O, Saito N, Koda K, Sarashina H, Nakajima N. Clinical assessment of positron emission tomography for the diagnosis of local recurrence in colorectal cancer. Br J Surg 1999;86: Keogan MT, Lowe VJ, Baker ME, McDermott VG, Lyerly HK, Coleman RE. Local recurrence of rectal cancer: evaluation with F-18 fluorodeoxyglucose PET imaging. Abdom Imaging 1997;22: Calvo FA, Domper M, Matute R, et al. 18 F-FDG positron emission tomography staging and restaging in rectal cancer treated with preoperative chemoradiation. Int J Radiat Oncol Biol Phys 2004;58: Janicke DM, Pundt MR. Anorectal disorders. Emerg Med Clin North Am 1996;14: Berkelhammer C, Moosvi SB. Retroflexed endoscopic band ligation of bleeding internal hemorrhoids. Gastrointest Endosc 2002;55: Thomson WH. The nature of hemorrhoids. Br J Surg 1975;62: Chung YC, Hou YC, Pan AC. Endoglin (CD105) expression in the development of haemorrhoids. Eur J Clin Invest 2004; 34: Nisar PJ, Scholefield JH. Managing haemorrhoids. BMJ 2003;327: Tamura M, Unno K, Yonezawa S, et al. In vivo trafficking of endothelial progenitor cells: their possible involvement in tumor neovascularization. Life Sci 2004;75: ;19:

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5 -18-FDG High FDG uptake in hemorrhoid -18-FDG FDG 18-FDG FDG 2006;19: (04) (04) wylin@vghtc.vghtc.gov.tw 2006;19: