This document describes and provides images of 14 different types of cystic retroperitoneal masses that can be identified on clinical imaging, including pancreatic pseudocysts, lymphoceles, urinomas, hematomas, cystic lymphangiomas, lymphangioleiomyomas, mucinous cystadenomas, cystic teratomas, Mullerian cysts, epidermoid cysts, tailgut cysts, cystic changes in solid neoplasms such as paragangliomas and neurilemomas, pseudomyxoma retroperitonei from a ruptured mucinous cystadenocarcinoma of the appendix, and perianal mucinous adenocarcinoma.

1. 42Cystic Retroperitoneal
Mass

2. CLINICAL IMAGAGING
AN ATLAS OF DIFFERENTIAL DAIGNOSIS
EISENBERG
DR. Muhammad Bin Zulfiqar
PGR-FCPS III SIMS/SHL

3. • Fig GU 42-1 Pancreatic pseudocyst. Thin-
walled fluid collection in the anterior
pararenal space (arrow).56

4. • Fig GU 42-2 Lymphocele. Hypoattenuating
cystic mass located in the obturator space
(arrows) and compressing the urinary bladder
(B) in this woman who three months
previously had undergone a radical
hysterectomy for cervical cancer.56

5. • Fig GU 42-3 Urinoma. Large fluid collection
with ring enhancement in the presarcal space
(arrow) in a woman who had undergone
radical hysterectomy for cervical cancer.56

6. • Fig GU 42-4 Hematoma. Huge cystic mass with
thin walls in the right retroperitoneal space
(arrow).56

7. • Fig GU 42-5 Cystic lymphangioma. Lobulated
cystic mass in the anterior pararenal space.
The third portion of the duodenum is
compressed by the mass.56

8. • Fig GU 42-6 Lymphangioleiomyoma. Large
cystic retroperitoneal masses fill the lower
abdomen. Note the fat-fluid level (arrow).57

9. • Fig GU 42-7 Mucinous cystadenoma. Large
mass of homogeneously low attenuation in
the right anterior pararenal space (arrow).56

10. • Fig GU 42-8 Cystic teratoma. Well-defined
hypoattenuating mass with internal septa and
calcifications in the right anterior pararenal
space (arrow).56

11. • Fig GU 42-9 Mullerian cyst. Well-defined cystic
mass in the left retroperitoneal space
(arrow).56

12. • Fig GU 42-10 Epidermoid cyst. Well-defined
hypoatttenuating mass in the pelvic
retroperitoneum (thick arrow). There is
anterior displacement of the rectum (thin
arrow).56

13. • Fig GU 42-11 Tailgut cyst. Well-defined, thin-
walled multicystic mass in the presacral space
(thin arrows). The rectum is compressed and
anteriorly displaced (thick arrow).56

14. • Fig GU 42-12 Cystic change in solid neoplasm.
(A) Paraganglioma appears as a cystic mass
with irregular walls in the right anterior
pararenal space (arrow). (B) Neurilemoma
appears as a cystic mass in the pelvic
retroperitoneum (arrow).56

15. • Fig GU 42-13 Pseudomyxoma retroperitonei
(from rupture of a mucinous cystadenocarcinoma
of the appendix). Lobulated low-attenuation
masses in the right lower quadrant (thick arrows),
mass effect on the right psoas muscles and right
ureter, and a tiny wall calcification (thin arrow).56

16. • Fig GU 42-14 Perianal mucinous
adenocarcinoma. Thin-walled collection in the
anterior pararenal space (arrow).56