INTERESTING IMAGE
Increased
18
F-FDG Uptake by a Retroperitoneal Mature Cystic Teratoma in an Infant
Young Joo Suh, MD, Myung-Joon Kim, MD, PhD, and Mi-Jung Lee, MD, PhD Abstract: A teratoma is a nonseminomatous germ cell tumor composed of well-differentiated derivations from at least 2 of the 3 germ layers. Mature cystic teratomas are known to have low metabolic activity and do not exhibit increased FDG uptake on PET. We report a case of mature cystic teratoma of the retroperitoneum showing increased FDG uptake in the solid portion. Pathologically, the solid portion was composed of abundant central nervous tissue. Increased FDG uptake in a teratoma may be not only due to an immature or malignant component but also to the presence of central nervous tissue. Key Words: teratoma, germ cell tumor, PET (Clin Nucl Med 2014;39: 352Y354)
Received for publication October 30, 2012; revision accepted April 5, 2013. From the Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, Seoul, Korea. Conflicts of interest and sources of funding: none declared. Reprints: Mi-Jung Lee, MD, PhD, Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, 50 Yonsei-ro, Seodaemun-gu, 120-752 Seoul, Korea. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3904Y0352
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REFERENCES 1. Xu Y, Wang J, Peng Y, et al. CT characteristics of primary retroperitoneal neoplasms in children. Eur J Radiol. 2010;75:321Y328. 2. Maslin P, Luchs JS, Haas J, et al. Ovarian teratoma with malignant transformation: CT diagnosis. AJR Am J Roentgenol. 2002;178:1574. 3. Ueno T, Tanaka YO, Nagata M, et al. Spectrum of germ cell tumors: from head to toe. Radiographics. 2004;24:387Y404. 4. De Giorgi U, Pupi A, Fiorentini G, et al. FDG-PET in the management of germ cell tumor. Ann Oncol. 2005;16(suppl 4):iv90Yiv94. 5. Balink H, Apperloo MJ, Collins J. Assessment of ovarian teratoma and lymphadenopathy by 18F-FDG PET/CT. Clin Nucl Med. 2012;37:804Y806. 6. Park SA, Kim TY, Choi SS, et al. (1)(8)F-FDG PET/CT imaging for mixed germ cell tumor in the pineal region. Clin Nucl Med. 2012;37:e61Ye63. 7. Miyasaka N, Kubota T. Unusually intense (1)F-fluorodeoxyglucose (FDG) uptake by a mature ovarian teratoma: a pitfall of FDG positron emission tomography. J Obstet Gynaecol Res. 2011;37:623Y628. 8. Yoshikata R, Yamamoto T, Kobayashi M, et al. Immunohistochemical characteristics of mature ovarian cystic teratomas in patients with postoperative recurrence. Int J Gynecol Pathol. 2006;25:95Y100.
Clinical Nuclear Medicine
& Volume 39, Number 4, April 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Clinical Nuclear Medicine
& Volume 39, Number 4, April 2014
FDG Uptake by a Mature Cystic Teratoma
FIGURE 1. A 7-month-old female baby with abdominal distention. A, Abdominal ultrasonography image of the infant shows a huge multi-septated cystic mass with lobulated solid portions (arrow) in the left abdomen. B, Coronal reformatted CT image also shows a huge cystic mass displacing the left kidney (arrowhead ) inferiorly. The mass shows internal septations and some enhancing solid areas (arrow) in the upper portion of the mass.
FIGURE 2. 18F-FDG PET scan image shows increased FDG uptake in the solid portion (arrow) of the mass and the mean standardized uptake value (SUVmean) of the solid portion was measured to be 4.1, suggesting high metabolic activity indicative of malignant potential. The serum >-fetoprotein level was elevated in this patent (27.17 ng/mL). These imaging and laboratory findings were strongly suggestive of retroperitoneal cystic teratoma with an immature or malignant component. The patient subsequently underwent excision of this mass. * 2013 Lippincott Williams & Wilkins
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Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
353
Clinical Nuclear Medicine
Suh et al
& Volume 39, Number 4, April 2014
FIGURE 3. On histopathologic examination, the tumor was found to consist of endodermal, mesodermal, and ectodermal elements, including elements from the intestinal epithelium, adipose tissue, hair follicle, skin, and central nervous tissue. Among these elements, central nervous tissue was notably abundant in the solid component. No immature or malignant elements were found, indicating a benign mature teratoma. Primary retroperitoneal nonseminomatous germ cell tumor (NSGCT) is a rarely encountered neoplasm, accounting for only 1%Y2.5% of all germ cell tumors.1 Teratomas may have an immature component, which is more likely to undergo malignant transformation than a mature teratoma.1 The presence of hemorrhage or necrosis in a predominantly solid mass and invasion of adjacent structures are suggestive of malignancy.1,2 However, mature cystic teratomas sometimes have a large, solid area.3 An elevated serum >-fetoprotein level is noted in only 50% of cases. Therefore, differentiation between mature and immature teratomas is often difficult.3 Generally, mature cystic teratomas are known to have low metabolic activity and do not exhibit increased FDG uptake on PET.4 However, our case showed increased FDG uptake in the solid portion of the benign mature teratoma and pathologically the solid portion was composed of abundant central nervous tissue. PET scans could be useful in determining the degree of malignancy in NSGCT,5 even in intracranial location.6 And there is only 1 report of a mature cystic teratoma originating from the ovary showing increased FDG uptake, which was attributed to the central nervous tissue in the solid component of the tumor.7 The increased FDG uptake in that case was explained by glucose metabolism in the brain tissue. Glucose is the primary fuel for the brain and a high concentration of glucose transporters is present in brain tissues, such as neurons and glial cells. Central nervous tissue is reported as one of the most frequently found components of ovarian teratoma,8 although the exact proportions are not known in the other site. Clinicians should keep in mind that the presence of central nervous tissue can be one cause of increased FDG uptake in a mature teratoma.
354
www.nuclearmed.com
* 2013 Lippincott Williams & Wilkins
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Increased
18
F-FDG Uptake by a Retroperitoneal Mature Cystic Teratoma in an Infant
Young Joo Suh, MD, Myung-Joon Kim, MD, PhD, and Mi-Jung Lee, MD, PhD Abstract: A teratoma is a nonseminomatous germ cell tumor composed of well-differentiated derivations from at least 2 of the 3 germ layers. Mature cystic teratomas are known to have low metabolic activity and do not exhibit increased FDG uptake on PET. We report a case of mature cystic teratoma of the retroperitoneum showing increased FDG uptake in the solid portion. Pathologically, the solid portion was composed of abundant central nervous tissue. Increased FDG uptake in a teratoma may be not only due to an immature or malignant component but also to the presence of central nervous tissue. Key Words: teratoma, germ cell tumor, PET (Clin Nucl Med 2014;39: 352Y354)
Received for publication October 30, 2012; revision accepted April 5, 2013. From the Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, Seoul, Korea. Conflicts of interest and sources of funding: none declared. Reprints: Mi-Jung Lee, MD, PhD, Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, 50 Yonsei-ro, Seodaemun-gu, 120-752 Seoul, Korea. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3904Y0352
352
www.nuclearmed.com
REFERENCES 1. Xu Y, Wang J, Peng Y, et al. CT characteristics of primary retroperitoneal neoplasms in children. Eur J Radiol. 2010;75:321Y328. 2. Maslin P, Luchs JS, Haas J, et al. Ovarian teratoma with malignant transformation: CT diagnosis. AJR Am J Roentgenol. 2002;178:1574. 3. Ueno T, Tanaka YO, Nagata M, et al. Spectrum of germ cell tumors: from head to toe. Radiographics. 2004;24:387Y404. 4. De Giorgi U, Pupi A, Fiorentini G, et al. FDG-PET in the management of germ cell tumor. Ann Oncol. 2005;16(suppl 4):iv90Yiv94. 5. Balink H, Apperloo MJ, Collins J. Assessment of ovarian teratoma and lymphadenopathy by 18F-FDG PET/CT. Clin Nucl Med. 2012;37:804Y806. 6. Park SA, Kim TY, Choi SS, et al. (1)(8)F-FDG PET/CT imaging for mixed germ cell tumor in the pineal region. Clin Nucl Med. 2012;37:e61Ye63. 7. Miyasaka N, Kubota T. Unusually intense (1)F-fluorodeoxyglucose (FDG) uptake by a mature ovarian teratoma: a pitfall of FDG positron emission tomography. J Obstet Gynaecol Res. 2011;37:623Y628. 8. Yoshikata R, Yamamoto T, Kobayashi M, et al. Immunohistochemical characteristics of mature ovarian cystic teratomas in patients with postoperative recurrence. Int J Gynecol Pathol. 2006;25:95Y100.
Clinical Nuclear Medicine
& Volume 39, Number 4, April 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Clinical Nuclear Medicine
& Volume 39, Number 4, April 2014
FDG Uptake by a Mature Cystic Teratoma
FIGURE 1. A 7-month-old female baby with abdominal distention. A, Abdominal ultrasonography image of the infant shows a huge multi-septated cystic mass with lobulated solid portions (arrow) in the left abdomen. B, Coronal reformatted CT image also shows a huge cystic mass displacing the left kidney (arrowhead ) inferiorly. The mass shows internal septations and some enhancing solid areas (arrow) in the upper portion of the mass.
FIGURE 2. 18F-FDG PET scan image shows increased FDG uptake in the solid portion (arrow) of the mass and the mean standardized uptake value (SUVmean) of the solid portion was measured to be 4.1, suggesting high metabolic activity indicative of malignant potential. The serum >-fetoprotein level was elevated in this patent (27.17 ng/mL). These imaging and laboratory findings were strongly suggestive of retroperitoneal cystic teratoma with an immature or malignant component. The patient subsequently underwent excision of this mass. * 2013 Lippincott Williams & Wilkins
www.nuclearmed.com
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
353
Clinical Nuclear Medicine
Suh et al
& Volume 39, Number 4, April 2014
FIGURE 3. On histopathologic examination, the tumor was found to consist of endodermal, mesodermal, and ectodermal elements, including elements from the intestinal epithelium, adipose tissue, hair follicle, skin, and central nervous tissue. Among these elements, central nervous tissue was notably abundant in the solid component. No immature or malignant elements were found, indicating a benign mature teratoma. Primary retroperitoneal nonseminomatous germ cell tumor (NSGCT) is a rarely encountered neoplasm, accounting for only 1%Y2.5% of all germ cell tumors.1 Teratomas may have an immature component, which is more likely to undergo malignant transformation than a mature teratoma.1 The presence of hemorrhage or necrosis in a predominantly solid mass and invasion of adjacent structures are suggestive of malignancy.1,2 However, mature cystic teratomas sometimes have a large, solid area.3 An elevated serum >-fetoprotein level is noted in only 50% of cases. Therefore, differentiation between mature and immature teratomas is often difficult.3 Generally, mature cystic teratomas are known to have low metabolic activity and do not exhibit increased FDG uptake on PET.4 However, our case showed increased FDG uptake in the solid portion of the benign mature teratoma and pathologically the solid portion was composed of abundant central nervous tissue. PET scans could be useful in determining the degree of malignancy in NSGCT,5 even in intracranial location.6 And there is only 1 report of a mature cystic teratoma originating from the ovary showing increased FDG uptake, which was attributed to the central nervous tissue in the solid component of the tumor.7 The increased FDG uptake in that case was explained by glucose metabolism in the brain tissue. Glucose is the primary fuel for the brain and a high concentration of glucose transporters is present in brain tissues, such as neurons and glial cells. Central nervous tissue is reported as one of the most frequently found components of ovarian teratoma,8 although the exact proportions are not known in the other site. Clinicians should keep in mind that the presence of central nervous tissue can be one cause of increased FDG uptake in a mature teratoma.
354
www.nuclearmed.com
* 2013 Lippincott Williams & Wilkins
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
