FDG-PET Findings in an Ovarian Endometrioma: A Case Report

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1 FDG-PET Findings in an Ovarian Endometrioma: A Case Report Jia-Huei Lin 1, Victor Chit-kheng Kok 2, Jian-Chiou Su 3 1 Department of Nuclear medicine, Kuang Tien General Hospital, Sha-Lu, Taichung, Taiwan 2 Division of Medical Oncology, Department of Internal Medicine, Kuang Tien General Hospital, Sha-Lu, Taichung, Taiwan 3 Division of General Surgery, Kuang Tien General Hospital, Sha-Lu, Taichung, Taiwan Endometriosis is a common medical condition with rare reports of FDG findings in the scintigraphic literature. We present a 36-year-old premenopausal woman with a left ovarian endometrioma that presents a photopenic defect on the FDG-PET scan. The case demonstrates the value of FDG-PET scan in differentiating benign from malignancy in surveying ovarian lesions. The literature associated with endometriomas and FDG-PET scan, and the factors that may contribute to FDG-PET finding of endometriomas are discussed. Key words: FDG-PET, ovarian endometrioma, photopenic Ann Nucl Med Sci 2008;21: Received 12/6/2007; revised 12/17/2007; accepted 12/25/2007. For correspondence and reprints contact: Jia-Huei Lin, M.D., Department of Nuclear medicine, Kuang Tien General Hospital. 117 Sha-Tien Road, Sha-Lu, Taichung 43303, Taiwan, ROC. Tel: (886) ext. 2056, Fax: (886) , address: lin.jiahuei@msa.hinet.net Introduction Endometriosis is a common medical condition characterized by growth of tissue like endometrium beyond or outside the uterus [1-4]. Most endometriosis is found on structures in the pelvic cavity, including ovaries, fallopian tubes, the back and front of the uterus, uterine ligaments, intestines and urinay bladder. The common imaging tests are ultrasound and magnetic resonance imaging (MRI), which may identify larger endometriotic nodules of cysts. Laparoscopy allows for definite confirmation an endometriosis diagnosis as well as surgical treatment. 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan, which reflects the amount of metabolism, are recently used to characteristize an ovarian lesion in addition to other imaging modalities [5-8]. Herein we present a case with endometrioma and the FDG- PET findings. Case Report A 36-year-old premenopausal woman with a history of cesarean section had occasional lower abdominal tenderness occurring with her periods for 6 months. The pelvic ultrasound examination showed a left ovarian cyst about 5 cm in diameter without internal blood flow (Figure 1). Benign endometrioma was favored according to the findings of ultrasound. The CA125 level was elevated (48.19 unit/ml, reference range < 35.0 unit/ml). The alpha-fetal protein (AFP) level and beta-human chorionic gonadotrophin (beta-hcg) were within normal reference range. However, the patient required a self-pay FDG-PET to differentiate benign lesions from malignancies. The PET scan obtained one hour after intravenous injection of 11.3 mci FDG revealed a photopenic area in the left posterior pelvis (Figure 2). Follow-up was suggested due the clinical benign impression. However, the lower abdominal tenderness with her period persisted for 2 months. Laparoscopy oophrocystectomy was thus suggested. Laparoscopy showed a left ovarian cyst with coffee fluid content. Left oophocystectomy was done and the pathology

Lin JH et al showed endometriosis. Left ovarian endometrioma was diagnosed. After surgery she underwent four courses of leuprorelin acetate depot followed by oral contraceptive pill.

The ultrasound of gynecology shows a complex mass, about 68 45 50 mm in size, predominant cyst, in the left adnexa with no internal flow.

2 Lin JH et al showed endometriosis. Left ovarian endometrioma was diagnosed. After surgery she underwent four courses of leuprorelin acetate depot followed by oral contraceptive pill. The symptoms of periodic lower abdominal tenderness remised during clinical follow-up for 8 months. Figure 1. The ultrasound of gynecology shows a complex mass, about mm in size, predominant cyst, in the left adnexa with no internal flow. Discussion FDG-PET scan is well known with the value in differentiating benign from malignant lesions, for which the FDG- PET scan was indicated in the present case. Ovarian endometriosis may present as a pelvis mass arising from growth of ectopic endometrial tissue within the ovary, so called ovarian endometrioma. Ovarian endometrioma sometimes have a solid nodule component due to focal endometrial tissue, which make it difficult to distinguish an endomerioma from the true solid tissue of a neoplasm. In three series studying patients with asymptomatic adenxal mass, the diagnostic performance of FDG-PET, MRI and transvaginal ultrasound were evaluated [5-7]. In differentiating benign Figure 2. The FDG-PET scan shows a photopenic area (arrows) in the left posterior pelvis, corresponding to the left adenxal mass on the ultrasound. The focal FDG-accumulated areas surrounding the photopenic area disappears in the delayed image, probably due to physiologic bowel activity. Ann Nucl Med Sci 2008;21: Vol. 21 No. 2 June

3 FDG-PET FDG-PET findings in an ovarian endometrioma from malignant asymptomatic adnexal mass, the sensitivity, specificity and accuracy were 58%, 76% to 80% and 74% to 77% for FDG-PET; 83%, 84% and 83% to 84% for MRI, and 92%, 59% to 60% and 63% to 64% for transvaginal ultrasound. Although combination of ultrasound with MRI and FDG-PET scan may improve accuracy, they pointed out that negative FDG-PET results do not rule out early-stage ovarian cancer or borderline malignancies. In Castellucci s study surveying 50 patients with pelvic lesions with FDG- PET/CT and transvaginal ultrasound, the sensitivity, specificity and accuracy was 87%, 100% and 92% for FDG- PET/CT, and 90%, 61% and 80% for transvaginal ultrasound. They concluded that FDG-PET/CT provides additional value to ultrasound for the differential diagnosis of benign from malignant pelvic lesions [8]. Although in the present case the hypometabolic finding of the pelvis mass is consistent with the benign pathologic result of endometrioma, combination of clinical presentation with other imaging modality and histopathology are still required to make a precise diagnosis to avoid false-negative FDG-PET result in early-stage ovarian cancer or borderline malignancies. The ovaries are the first of the most common sites of endometriosis. Although ovarian endometrioma is not a rare disease, only few reports have mentioned its characteristics in FDG uptake. Holder et al [9] studied 103 FDG-PET scans of 76 patients with melanoma. One of them showed falsepositive PET scan due to endometriosis. Rieber et al [7] observed false-positive FDG PET results in 4 of 22 endometriomas in surveying 103 women with suspicious adnexal findings on ultrasound. In Fenchel s study [5], 18 of 23 endometriomas did not show elevated FDG uptake while 5 did. In only one of the five cases the elevated FDG uptake could be clearly attributed to the tumor mass in the review of PET and MRI. Jeffry et al [10] reported a 32-year-old woman with left ovarian endometrioma and FDG uptake in the right paravesical area, assumed to be associated with inflammation rather to a cyst. Recently, Derman et al [11] reported a 47-year-old woman who had a pulmonary endometrioma with intense FDG uptake. Most of the reports in the literature demonstrate that the majority of endometriomas have low FDG metabolism with few exceptions. Although the exact mechanism is not clear, two factors may contribute to the FDG uptake in endomertiomas. First, the FDG uptake in the normal endometrial glands may be associated with the menstrual cycle. The endometrial gland may show FDG uptake especially during menstrual flow phase and ovulatory phase [12-14]. Whether endometriomas would show FDG uptake during those phases is not well understood. Since the endometriosis is defined as ectopic endometrial gland outside the endometrial cavity and uterine musculature, it might show FDG uptake as well as the endometrium of the uterus in those phases [11]. Second, the endometriomas may show FDG uptake secondary to triggered inflammation [10]. In conclusion, the ovarian endotrioma shows low FDG uptake in the present case. The FDG-PET scan offer important clinical information in survey an ovarian cystic lesion. References 1. Brosens I, Puttemans P, Campo R, Gordts S, Kinkel K. Diagnosis of endometriosis: pelvic endoscopy and imaging techniques. Best Pract Res Clin Obstet Gynaecol 2004;18: Solnik MJ. Chronic pelvic pain and endometriosis in adolescents. Curr Opin Obstet Gynecol 2006;18: Vigano P, Parazzini F, Somigliana E, Vercellini P. Endometriosis: epidemiology and aetiological factors. Best Pract Res Clin Obstet Gynaecol 2004;18: Hompes PG, Mijatovic V. Endometriosis: the way forward. Gynecol Endocrinol 2007;23: Fenchel S, Grab D, Nuessle K, et al. Asymptomatic adnexal masses: correlation of FDG PET and histopathologic findings. Radiology 2002;223: Grab D, Flock F, Stohr I, et al. Classification of asymptomatic adnexal masses by ultrasound, magnetic resonance imaging, and positron emission tomography. Gynecol Oncol 2000;77: Rieber A, Nussle K, Stohr I, et al. Preoperative diagnosis of ovarian tumors with MR imaging: comparison with transvaginal sonography, positron emission tomography, and histologic findings. AJR Am J Roentgenol 2001;177: Castellucci P, Perrone AM, Picchio M, et al. Diagnostic 2008;21:

4 Lin JH et al accuracy of 18 F-FDG PET/CT in characterizing ovarian lesions and staging ovarian cancer: correlation with transvaginal ultrasonography, computed tomography, and histology. Nucl Med Commun 2007;28: Holder WD Jr, White RL Jr, Zuger JH, Easton EJ Jr, Greene FL. Effectiveness of positron emission tomography for the detection of melanoma metastases. Ann Surg 1998;227: Jeffry L, Kerrou K, Camatte S, et al. Endometriosis with FDG uptake on PET. Eur J Obstet Gynecol Reprod Biol 2004;117: Derman AY, Sperling D, Merav A, et al. Endometrioma presenting as a cavitary lung mass with intense 18 F-FDG uptake on PET-CT. J Thorac Imaging 2007;22: Lerman H, Metser U, Grisaru D, Fishman A, Lievshitz G, Even Sapir E. Normal and abnormal 18 F-FDG endometrial and ovarian uptake in pre- and postmenopausal patients: assessment by PET/CT. J Nucl Med 2004;45: Nishizawa S, Inubushi M, Okada H. Physiological 18 F- FDG uptake in the ovaries and uterus of healthy female volunteers. Eur J Nucl Med Mol Imaging 2005;32: Zhu Z, Wang B, Cheng W, et al. Endometrial and ovarian F-18 FDG uptake in serial PET studies and the value of delayed imaging for differentiation. Clin Nucl Med 2006;31: Ann Nucl Med Sci 2008;21: Vol. 21 No. 2 June

5 FDG-PET FDG-PET findings in an ovarian endometrioma ;21: (04) (04) lin.jiahuei@msa.hinet.net 2008;21:

FDG-PET value in deep endometriosis

Gynecol Surg (2011) 8:305 309 DOI 10.1007/s10397-010-0652-6 ORIGINAL ARTICLE FDG-PET value in deep endometriosis A. Setubal & S. Maia & C. Lowenthal & Z. Sidiropoulou Received: 3 December 2010 / Accepted: