SPR Unknown # 85 -- FINAL

Liz Overstreet

Lurie Children's Hospital


Mary Wyers, M.D.

Lurie Children's Hospital



6 month old with abdominal mass discovered on physical exam


1810 Retroperitoneal Mature Cystic Teratoma Germ Cell Tumor CT

Publication Date: 2013-02-22


6 month old with abdominal mass discovered on physical exam


CT: Large, predominately cystic mass located in the left retroperitoneal space and extends across the midline. The mass contains solid and differentiated ossified components and has no fat density present. There is significant mass effect on the abdominal aorta and IVC as well as on the left kidney.


Retroperitoneal Mature Cystic Teratoma


Retroperitoneal Teratoma, Fetus in Fetu, neuroblastoma can be in the retroperitoneum although does not typically have ossified elements at presentation


Teratomas, a type of germ cell tumor, are composed of tissues derived from at least two of the three germ cell layers: ectoderm, mesoderm, and endoderm. Additionally, the tissues comprising the teratoma are typically foreign to the anatomic site of the tumor. These tissues are also in various stages of maturity.

Common sites of origin include the ovaries, testes, mediastinum, and sacrococcygeal region. Teratomas can be classified as mature, immature, or mixed. This classification is based upon on the degree of differentiation of the tumor’s components.

Retroperitoneal teratomas are uncommon and comprise <10% of all primary retroperitoneal tumors. They tend to be mature tumors and can sometimes resemble fetal elements, which leads to the differential diagnosis of fetus-in-fetu. They occur most often in females, with a female to male ratio of 2:1. This type of teratoma is commonly diagnosed in newborns.

Mature retroperitoneal teratomas are often complex masses that have a well-circumscribed fluid component, adipose tissue, and calcification. The presence of hypoattenuating fat within a cyst is often a good indicator of a cystic teratoma but is not always present. Plain films may demonstrate the soft tissue mass with irregular calcification while ultrasound is useful in examining the relationship of the mass to its adjacent structures. Finally, a CT scan can definitively demonstrate the soft tissue, fat, fluid, and calcific components of the masses.

Retroperitoneal teratomas are almost always surgically resected and depending on the malignancy of the tumor, chemotherapy is sometimes utilized.



  1. Loo CC, Huang CS, Chu, SM, et al. Retroperitoneal teratomas in infancy and childhood. 2005 Pediatric Surgery International, 21; 536-540.
  2. Peterson C, Buckley C, Holley, S, et al. Teratomas: A Multimodality Review. November/December 2012 Current Problems in Diagnostic Radiology; 210-219.
  3. Yang D, Jung D, Kim H, et al. Retroperitoneal Cystic Masses: CT, Clinical, and Pathologic Findings and Literature Review. September 2004 RadioGraphics, 24;1353-1365

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