INTERESTING IMAGE
Organized Urachal Abscess Mimicking Urachal Carcinoma on FDG PET/CT Aisheng Dong, MD,* Changjing Zuo, MD,* Yang Wang, MSc,Þ Jianping Lu, MD,þ and Haiyun Zhu, MD§ Abstract: Urachal inflammation is rarely seen in adults. Two patients with suspected abdominal tumor underwent FDG PET/CT. One patient showed an irregular hypermetabolic mass anterosuperior to the bladder. The other patient showed a thick-walled cystic mass with strong FDG uptake extending from the bladder dome to the anterior abdominal wall. Urachal carcinomas were suspected based on imaging findings. Both patients underwent complete resection of the masses. However, both masses were organized urachal abscesses confirmed by pathological examination. These two cases highlight that differentiation between organized urachal abscess and carcinoma is difficult on the basis of imaging. Key Words: urachal abscess, inflammation, urachal carcinoma, MRI, FDG PET (Clin Nucl Med 2014;39: 71Y73)
Received for publication July 31, 2012; revision accepted October 15, 2012. From the Departments of *Nuclear Medicine, †Pathology, and ‡Radiology, Changhai Hospital; and §Department of Radiology, 85 Hospital, Shanghai, China. Conflicts of interest and sources of funding: A.D. was sponsored by Young Scholar Grant from National Natural Science Foundation of China (81000601). Reprints: Haiyun Zhu, MD, Department of Radiology, 85 Hospital, 1328 Huashan Rd, Shanghai 200052, China. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3901Y0071
Clinical Nuclear Medicine
& Volume 39, Number 1, January 2014
REFERENCES 1. Yu JS, Kim KW, Lee HJ, et al. Urachal remnant diseases: spectrum of CT and US findings. Radiographics. 2001;21:451Y461. 2. Spataro RF, Davis RS, McLachlan MS, et al. Urachal abnormalities in the adult. Radiology. 1983;149:659Y663. 3. Cutting CW, Hindley RG, Poulsen J. Laparoscopic management of complicated urachal remnants. BJU Int. 2005;96:1417Y1421. 4. Blichert-Toft M, Nielsen OV. Congenital patient urachus and acquired variants. Diagnosis and treatment. Review of the literature and report of five cases. Acta Chir Scand. 1971;137:807Y814. 5. Nimmonrat A, Na-ChiangMai W, Muttarak M. Urachal abnormalities: clinical and imaging features. Singapore Med J. 2008;49:930Y935. 6. Nakajo M, Jinnouchi S, Arimura H, et al. FDG PET/CT findings of urachal abscess. Clin Nucl Med. 2008;33:579Y581. 7. Lim KT, Moon SJ, Kwon JS, et al. Urachal actinomycosis mimicking a urachal tumor. Korean J Urol. 2010;51:438Y440. 8. Belakhlef S, Church C, Jani C, et al. Early dynamic PET/CT and 18F-FDG blood flow imaging in bladder cancer detection: a novel approach. Clin Nucl Med. 2012;37:366Y368. 9. Liu Y. Primary umbilical neoplasm demonstrated on FDG PET/CT. Clin Nucl Med. 2011;36:e67Ye68. 10. Me´tivier D Jr, Bonardel G, Rouquie D, et al. 18F-FDG PET/CT imaging of Sister Mary Joseph’s nodule. Clin Nucl Med. 2012;37:486Y488. 11. Nguyen BD, Roarke MC. Postlaparoscopic abdominal port-site metastasis: F-18 FDG PET/CT demonstration. Clin Nucl Med. 2007;32:732Y734. 12. Basu S, Desai SB. Solitary anterior abdominal wall metastasis from osteogenic sarcoma of fibula as detected by FDG-PET imaging. J Cancer Res Ther. 2011;7:229Y230. 13. Anthony MP, Khong PL, Zhang J. Spectrum of (18)F-FDG PET/CT appearances in peritoneal disease. AJR Am J Roentgenol. 2009;193:W523YW529.
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Clinical Nuclear Medicine
Dong et al
& Volume 39, Number 1, January 2014
FIGURE 1. A 27-year-old woman was admitted to our hospital because of a 1-month history of lower abdominal pain and fullness. Transverse enhanced CT (A) in the venous phase showed that the lower portion of the mass (arrow) was close to the bladder dome with heterogeneous enhancement. Transverse enhanced CT (B) in the venous phase showed that the upper portion of the mass (arrow) was in the midanterior abdominal wall.
FIGURE 2. 18F FDG PET/CT scan was performed 1 hour after the injection of 385 MBq (10.4 mCi) of 18F FDG with a blood glucose level of 5 mmol/L. The maximum intensity projection PET image (A) showed an irregular FDG-avid mass in the lower abdomen (arrow) superior to the bladder. Transverse CT (B), corresponding PET (C), and fusion (D) images showed strong FDG uptake of the mass (arrow) with SUVmax of 14.1. Sagittal CT (E), corresponding PET (F), and fusion (G) images showed the mass (arrow) was anterosuperior to the bladder. Urachal carcinoma was suspected. The patient underwent resection of the mass. Organized urachal abscess is confirmed by pathological examination. 72
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* 2013 Lippincott Williams & Wilkins
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Clinical Nuclear Medicine
& Volume 39, Number 1, January 2014
Urachal Abscess Mimicking Urachal Carcinoma
FIGURE 3. A 62-year-old woman presented with a complaint of frequent urination, urgent urination, and urodynia for 3 months. Transverse (A) and sagittal (B) enhanced T1-weighted MR images in the venous phase showed a thick-walled cystic mass (arrow) superior to the bladder with marked enhancement of the thickened wall.
FIGURE 4. 18F FDG PET/CT scan was performed 1 hour after the injection of 374 MBq (10.1 mCi) of 18F FDG with a blood glucose level of 5.9 mmol/L. The maximum intensity projection PET image (A) showed an irregular FDG-avid mass in the lower abdomen (arrow) superior to the bladder. Transverse CT (B), corresponding PET (C), and fusion (D) images showed strong FDG uptake of the thickened wall (arrow) with SUVmax of 18.9. Sagittal CT (E), corresponding PET (F), and fusion (G) images showed the mass (arrow) extended from the bladder apex toward the umbilicus, suggesting an urachal mass. Urachal carcinoma was suspected. The patient underwent resection of the mass. Organized urachal abscess was confirmed by pathological examination.The urachus or median umbilical ligament is a midline tubular structure that extends upward from the anterior dome of the bladder toward the umbilicus.1 The tubular urachus normally involutes before birth, remaining as a fibrous band with no known function.1 Urachal diseases, including congenital or acquired, are usually seen in children and rare in adults.2,3 Congenital anomalies occur when the urachus fails to obliterate. Acquired diseases include inflammation and neoplasms.1 Urachal tract remnants that abnormally remain patent are often subject to infection.4Preoperative differentiation between urachal infection and carcinoma is difficult on the basis of imaging because both infection and carcinoma can present as a solid mass with adjacent organ involvement.5Y7 In our cases, it was also hard to differentiate the urachal abscess from urachal carcinoma base on CT, MRI, or FDG PET/CT.The differential diagnosis of urachal abscess should include urachal carcinoma,1,5 bladder carcinoma,8 umbilical neoplasm,9,10 abdominal wall metastasis,11,12 and peritoneal tumor.13 * 2013 Lippincott Williams & Wilkins
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73
Organized Urachal Abscess Mimicking Urachal Carcinoma on FDG PET/CT Aisheng Dong, MD,* Changjing Zuo, MD,* Yang Wang, MSc,Þ Jianping Lu, MD,þ and Haiyun Zhu, MD§ Abstract: Urachal inflammation is rarely seen in adults. Two patients with suspected abdominal tumor underwent FDG PET/CT. One patient showed an irregular hypermetabolic mass anterosuperior to the bladder. The other patient showed a thick-walled cystic mass with strong FDG uptake extending from the bladder dome to the anterior abdominal wall. Urachal carcinomas were suspected based on imaging findings. Both patients underwent complete resection of the masses. However, both masses were organized urachal abscesses confirmed by pathological examination. These two cases highlight that differentiation between organized urachal abscess and carcinoma is difficult on the basis of imaging. Key Words: urachal abscess, inflammation, urachal carcinoma, MRI, FDG PET (Clin Nucl Med 2014;39: 71Y73)
Received for publication July 31, 2012; revision accepted October 15, 2012. From the Departments of *Nuclear Medicine, †Pathology, and ‡Radiology, Changhai Hospital; and §Department of Radiology, 85 Hospital, Shanghai, China. Conflicts of interest and sources of funding: A.D. was sponsored by Young Scholar Grant from National Natural Science Foundation of China (81000601). Reprints: Haiyun Zhu, MD, Department of Radiology, 85 Hospital, 1328 Huashan Rd, Shanghai 200052, China. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3901Y0071
Clinical Nuclear Medicine
& Volume 39, Number 1, January 2014
REFERENCES 1. Yu JS, Kim KW, Lee HJ, et al. Urachal remnant diseases: spectrum of CT and US findings. Radiographics. 2001;21:451Y461. 2. Spataro RF, Davis RS, McLachlan MS, et al. Urachal abnormalities in the adult. Radiology. 1983;149:659Y663. 3. Cutting CW, Hindley RG, Poulsen J. Laparoscopic management of complicated urachal remnants. BJU Int. 2005;96:1417Y1421. 4. Blichert-Toft M, Nielsen OV. Congenital patient urachus and acquired variants. Diagnosis and treatment. Review of the literature and report of five cases. Acta Chir Scand. 1971;137:807Y814. 5. Nimmonrat A, Na-ChiangMai W, Muttarak M. Urachal abnormalities: clinical and imaging features. Singapore Med J. 2008;49:930Y935. 6. Nakajo M, Jinnouchi S, Arimura H, et al. FDG PET/CT findings of urachal abscess. Clin Nucl Med. 2008;33:579Y581. 7. Lim KT, Moon SJ, Kwon JS, et al. Urachal actinomycosis mimicking a urachal tumor. Korean J Urol. 2010;51:438Y440. 8. Belakhlef S, Church C, Jani C, et al. Early dynamic PET/CT and 18F-FDG blood flow imaging in bladder cancer detection: a novel approach. Clin Nucl Med. 2012;37:366Y368. 9. Liu Y. Primary umbilical neoplasm demonstrated on FDG PET/CT. Clin Nucl Med. 2011;36:e67Ye68. 10. Me´tivier D Jr, Bonardel G, Rouquie D, et al. 18F-FDG PET/CT imaging of Sister Mary Joseph’s nodule. Clin Nucl Med. 2012;37:486Y488. 11. Nguyen BD, Roarke MC. Postlaparoscopic abdominal port-site metastasis: F-18 FDG PET/CT demonstration. Clin Nucl Med. 2007;32:732Y734. 12. Basu S, Desai SB. Solitary anterior abdominal wall metastasis from osteogenic sarcoma of fibula as detected by FDG-PET imaging. J Cancer Res Ther. 2011;7:229Y230. 13. Anthony MP, Khong PL, Zhang J. Spectrum of (18)F-FDG PET/CT appearances in peritoneal disease. AJR Am J Roentgenol. 2009;193:W523YW529.
www.nuclearmed.com
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
71
Clinical Nuclear Medicine
Dong et al
& Volume 39, Number 1, January 2014
FIGURE 1. A 27-year-old woman was admitted to our hospital because of a 1-month history of lower abdominal pain and fullness. Transverse enhanced CT (A) in the venous phase showed that the lower portion of the mass (arrow) was close to the bladder dome with heterogeneous enhancement. Transverse enhanced CT (B) in the venous phase showed that the upper portion of the mass (arrow) was in the midanterior abdominal wall.
FIGURE 2. 18F FDG PET/CT scan was performed 1 hour after the injection of 385 MBq (10.4 mCi) of 18F FDG with a blood glucose level of 5 mmol/L. The maximum intensity projection PET image (A) showed an irregular FDG-avid mass in the lower abdomen (arrow) superior to the bladder. Transverse CT (B), corresponding PET (C), and fusion (D) images showed strong FDG uptake of the mass (arrow) with SUVmax of 14.1. Sagittal CT (E), corresponding PET (F), and fusion (G) images showed the mass (arrow) was anterosuperior to the bladder. Urachal carcinoma was suspected. The patient underwent resection of the mass. Organized urachal abscess is confirmed by pathological examination. 72
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* 2013 Lippincott Williams & Wilkins
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Clinical Nuclear Medicine
& Volume 39, Number 1, January 2014
Urachal Abscess Mimicking Urachal Carcinoma
FIGURE 3. A 62-year-old woman presented with a complaint of frequent urination, urgent urination, and urodynia for 3 months. Transverse (A) and sagittal (B) enhanced T1-weighted MR images in the venous phase showed a thick-walled cystic mass (arrow) superior to the bladder with marked enhancement of the thickened wall.
FIGURE 4. 18F FDG PET/CT scan was performed 1 hour after the injection of 374 MBq (10.1 mCi) of 18F FDG with a blood glucose level of 5.9 mmol/L. The maximum intensity projection PET image (A) showed an irregular FDG-avid mass in the lower abdomen (arrow) superior to the bladder. Transverse CT (B), corresponding PET (C), and fusion (D) images showed strong FDG uptake of the thickened wall (arrow) with SUVmax of 18.9. Sagittal CT (E), corresponding PET (F), and fusion (G) images showed the mass (arrow) extended from the bladder apex toward the umbilicus, suggesting an urachal mass. Urachal carcinoma was suspected. The patient underwent resection of the mass. Organized urachal abscess was confirmed by pathological examination.The urachus or median umbilical ligament is a midline tubular structure that extends upward from the anterior dome of the bladder toward the umbilicus.1 The tubular urachus normally involutes before birth, remaining as a fibrous band with no known function.1 Urachal diseases, including congenital or acquired, are usually seen in children and rare in adults.2,3 Congenital anomalies occur when the urachus fails to obliterate. Acquired diseases include inflammation and neoplasms.1 Urachal tract remnants that abnormally remain patent are often subject to infection.4Preoperative differentiation between urachal infection and carcinoma is difficult on the basis of imaging because both infection and carcinoma can present as a solid mass with adjacent organ involvement.5Y7 In our cases, it was also hard to differentiate the urachal abscess from urachal carcinoma base on CT, MRI, or FDG PET/CT.The differential diagnosis of urachal abscess should include urachal carcinoma,1,5 bladder carcinoma,8 umbilical neoplasm,9,10 abdominal wall metastasis,11,12 and peritoneal tumor.13 * 2013 Lippincott Williams & Wilkins
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73
