This article reviews the MRI appearance of cystic retroperitoneal (RP) masses.
Lymphangiomas are the most common RP cystic masses and typically appear simple; microscopic fat is a specific but insensitive finding. Location, internal complexity, and enhancement pattern suggest alternative diagnoses which range from normal anatomic variants to congenital abnormalities and importantly include benign, neurogenic, and malignant neoplasms. An approach to the MR imaging of cystic RP masses is presented.
Cystic masses of the retroperitoneum (RP) are uncommon; however, are encountered in clinical practice . CT is accurate for detection and preliminary characterization of the cystic nature of RP masses when internal areas measure fluid attenuation (i.e., between − 10 and 20 Hounsfield Units ); however, due to its improved soft tissue resolution and ability to differentiate between tissue types, MRI provides more accurate characterization of cystic RP masses . This article reviews the various cystic RP masses which may be encountered in clinical practice and presents an approach to improve characterization and differential diagnoses based upon imaging findings. Cystic RP masses which are typically confined to the pelvis, such as Mullerian cysts and tail gut cysts, have also been described in the literature  but are not further discussed in this article which focusses on the upper retroperitoneum.
A comprehensive technique for evaluation of the RP should emulate a dedicated renal mass MRI protocol and include: T1- and T2-weighted (W) imaging with and without fat suppression (FS), T1 W dual-echo in- and opposed-phase (IP and OP) imaging, diffusion-weighted imaging (DWI) and dynamic pre- and post-gadolinium enhanced FS T1W images in multiple planes . Our institutional protocol for characterization of renal and RP masses is provided in Table 1. An important aspect of RP mass MRI pertains to adequate coverage of a lesion in the cranio-caudal (CC) plane. When incidentally discovered, it is not uncommon for coverage of a lesion, particularly when more caudally located in the RP, to be incomplete on many sequences. This is especially true if the study was being performed for assessment of an upper abdominal organ such as the liver or spleen. When specifically performing MRI for RP mass characterization, it is helpful to review all available pre-procedural imaging and provide the vertebral body levels which cover the lesion (e.g., from Lumbar spine [LS]-2 to LS-5) to ensure adequate coverage. For larger lesions, on breath-hold sequences such as the pre- and post-enhanced images, adequate coverage may be difficult while maintaining a reasonable breath-hold duration. Helpful suggestions in these instances are to increase slice thickness or inter-slice gap or switch from axial to coronal plane which may improve coverage with less images acquired.
Normal anatomy and anatomic variants
The RP is defined as the space delineated anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. It is most commonly divided into three separate compartments known as the anterior pararenal space, the perirenal space, and the posterior pararenal space. The anterior pararenal space is bound by the posterior peritoneum and Gerota’s fascia. It contains the pancreas, ascending colon, and descending colon. The posterior pararenal space is bound by Zuckerkandl’s fascia and the transversalis fascia. It contains only fat, blood vessels, and lymphatics. The perirenal space is located in between and houses the kidneys and adrenal glands . Further details and illustrative depiction of the retroperitoneal anatomy are reviewed in depth in a recent article by Tirkes et al. .
A prominent cisterna chyli is an uncommonly identifiable structure on imaging which can mimic a cystic RP mass. Notably, it has been incidentally found in up to 20% of autopsy specimens and it is considered to be a normal anatomical variant, representing the convergence point of lumbar lymphatic channels. It can be seen as a saccular dilation coursing longitudinally within the retrocrural space, usually to the right of the aorta at the level of L1–L2. Alternatively, it can also have the appearance of multiple sacculations or of a plexus. It becomes the thoracic duct cranially . A dilated cisterna chyli (defined as 6 mm diameter or greater) has been found to be associated with decompensated liver cirrhosis with high specificity. It is thought that cirrhosis-induced portal hypertension causes increased pressure within the lymphatic system and subsequent dilatation of the cisterna chyli . On CT, a prominent cisterna chyli presents as a low-attenuating tubular structure which remains relatively stable in size over time. On MRI, pre-contrast signal intensity mirrors cerebral spinal fluid . The cisterna chyli may demonstrate slow, progressive delayed enhancement, for example after a 5-min delay, which has been reported to be a characteristic imaging finding, Fig. 1 .
Congenital or developmental cystic masses
RP lymphangiomas are benign congenital malformations thought to arise from sequestration of lymphatic tissue that is unable to drain into the remainder of the lymphatic system . Lymphangiomas are most frequently encountered within the head and neck (75%), the axilla (20%) and rarely, the abdomen (5%); however, lymphangiomas are the most common cystic masses found in the RP . RP lymphangiomas have a high rate of recurrence (10–100%) unless completely resected, after which the rate of recurrence drops substantially (0–27%) . On histopathology, they are characterized by cystic spaces lined by flat endothelial cells, lymphoid aggregates, foam cells and particularly smooth muscle cells . On CT, RP lymphangiomas are described as being homogenous, low attenuation masses with possible enhancement of the cyst wall or septae. Wall calcifications are rare. On MRI, a varied appearance has been described depending on internal contents, which may be serous, chylous, hemorrhagic or mixed, but generally lymphangiomas are hypointense or isointense to muscle on T1W and hyperintense on T2W images . Chyle is particularly rich in lipid content, therefore signal drop on out-of-phase imaging (due to microscopic fat) is highly specific for RP lymphangioma, Fig. 2. Nevertheless, this imaging finding can occur rarely in other cystic RP lesions such as dermoid cysts and lymphoceles .
Other congenital or developmental cystic RP masses are rare; however, should be kept in mind when formulating an imaging differential diagnosis. Bronchogenic cysts are congenital outpouchings arising from the primitive foregut. They are most commonly found above the diaphragm, in the mediastinum but have been depicted in case reports to occur in the RP. At histopathology, they are lined by secretory respiratory lining pseudostratified epithelium over a wall composed of hyaline fibrocartilage, seromucous glands, and/or smooth muscle cells . On CT, they are characterized as unilocular water-attenuation lesions with thin, smooth walls that do not enhance. Fluid–fluid levels with hyperdense material may be present in cases of hemorrhage, mucinous, or proteinaceous content . On MRI, they generally show isointense to hyperintense signal on T1W and hyperintense signal on T2W.
Benign and potentially malignant cystic masses
A variety of rare cystic benign or non-aggressive RP masses can be encountered in clinical practice. Imaging differentiation is usually limited; however, patient-related factors (e.g., age, size, symptoms) typically guide management which may range from observation to tissue sampling to surgical removal. Advances in image-guided procedures now allow for minimally invasive diagnosis of previously considered inaccessible RP lesions. In a study by Mehdi et al., high accuracy in diagnosis was achieved by using image-guided biopsy in 38 cases of cystic RP masses . Caution should be exerted when sampling metastatic lymph nodes with necrosis; however, as a hypocellular cystic aspirate may yield a false-negative result .
Teratomas or dermoid cysts are neoplasms containing tissue derived from all three germinal layers (mesoderm, ectoderm, and endoderm) which are not native to the location of the mass . They most often occur in women with a bimodal age of diagnosis ranging from infancy to young adulthood . They are commonly found within the ovaries but also occur in the RP, comprising 1–11% of all RP masses . Cystic teratomas are generally benign (mature), as opposed to solid teratomas which are generally malignant (immature) . On microscopic evaluation, cystic teratomas are often unilocular (containing sebum) and lined with squamous cell epithelium. There is often associated ectodermal elements (e.g., hair follicles, hair glands), mesodermal elements (e.g., fat, bone, cartilage, muscle), and endodermal elements (e.g., thyroid, gastrointestinal, pancreatic cells) . Complete surgical excision is warranted for definite diagnosis and to avoid malignant transformation, which can occur in 3–6% of cases . On imaging, teratomas are well-defined masses that displace but typically do not invade adjacent structures. The presence of internal macroscopic fat is highly suggestive; however, as discussed above, internal fat can be seen in other RP cystic masses. Notably, it could also be seen in RP pleomorphic liposarcomas with cystic or necrotic degeneration, although uncommon . Due to different combinations of cell lines, the imaging appearance is highly variable, ranging from purely cystic, Fig. 3, to mixed solid cystic . Calcifications are commonly encountered, which favors the diagnosis since calcifications are not commonly a feature of liposarcoma . A Rokitansky nodule or dermoid plug is an eccentric solid or cystic protrusion within a predominantly cystic mass which has also been described in both in ovarian and extragonadal cystic teratomas. On MRI, the sebaceous contents result in very high T1W signal and fat suppression is useful to differentiate fat from hemorrhage in these masses, as is the presence of chemical-shift artifact of the second kind .
Retroperitoneal abscesses are walled off, infected collections that most frequently arise due to renal infection, but can also occur as a result of infectious spondylodiscitis, perforated duodenal ulcers, perforated diverticulitis, or complicated cases of pancreatitis . Dropped gallstones are a less common cause for retroperitoneal abscess and can occur years following cholecystectomy . At contrast-enhanced CT, retroperitoneal abscesses present as thickened, rim-enhancing collections with surrounding inflammatory fat stranding. They may contain gas locules in the case of a gas-producing organism; however, the absence of air does not exclude the diagnosis . At MRI, abscesses have increased T2W signal and low T1W signal and similarly show rim enhancement post gadolinium administration with the added feature of restricted diffusion , Fig. 4. Treatment usually involves percutaneous or surgical drainage for collections greater than 3 cm as antibiotic therapy alone is usually not sufficient to eradicate the infection .
Hematomas  and urinomas  are also encountered in the RP and may present as cystic masses, particularly in a patient with previous history of trauma. Hemorrhage may occur spontaneously, especially in patients being treated with anticoagulant medications. On CT, urinomas show homogenous fluid density (< 20 HU) and are found along the urinary tract structures with a urographic phase potentially showing a communication to the opacified urinary system . Similar findings are documented on MRI. The MRI appearance of hematomas varies greatly depending on the age of the bleed. In the acute phase, hematomas tend to be hyperintense on both T1W and T2W images. In the more chronic phase (> 3 weeks), characteristic concentric rings have been described and are best seen on T1W images with variable signal intensity observed on T2W .
Primary and secondary malignant cystic masses
Primary malignant RP cystic masses are rare. Leiomyosarcoma of the inferior vena cava (IVC) is slow-growing, malignant neoplasm of the smooth muscle cells of the vessel wall with marked female preponderance. In 1992, the International IVC Leiomyosarcoma registry published a collection of only 218 total cases . Leiomyosarcomas spread locally, growing along the tissue planes and displacing adjacent structures without direct invasion but often metastasize to the lung and liver . Symptoms may relate to mass effect or venous occlusion if the tumor is intraluminal, such as Budd–Chiari or lower extremity edema/deep vein thrombosis. Treatment involves surgical resection and ligation of the IVC if there is the presence of collaterals, which is usually the case, or rarely with prosthetic replacement if venous collaterals are considered inadequate . At histological examination, leiomyosarcoma have a pattern of bundles of interlacing spindle-shaped cells with elongated nuclei . On MRI, these tumors are hypointense on T1W and heterogeneously T2W hyperintense. Focal areas of T1 hyperintensity may be present, indicative of hemorrhage. Enhancement, which may be confirmed using subtraction imaging, differentiates small endoluminal tumors growing into the IVC from the more commonly encountered bland thrombus. Differentiation of leiomyosarcoma from other RP masses may be challenging at imaging and hinges on depiction of close relation of the mass to the IVC wall. Venous collaterals may also be seen if there is occlusion of the IVC  (Fig. 5).
Serous and mucinous cystadenomas are frequently encountered within the ovaries or the pancreas, but very rare in the RP due to the lack of epithelial cells in this compartment. A review of the literature done by Navin et al. in 2012 identified only 18 cases of primary RP mucinous cystadenomas and less than 10 cases of serous cystadenomas in the English literature [40, 41]. The histopathogenesis remains unclear, but theories speculate that they could originate from heterotopic ovarian tissue  or from pluripotent mesothelial cells trapped within the abdomen . Histologically, RP cystadenomas are very similar to their ovarian counterparts but do not show ovarian cells. They demonstrate tall columnal epithelium with basal nuclei lining a stroma of fibrous connective tissue . Exploratory laparotomy with complete excision and enucleation of the cyst is indicated for treatment of RP cystadenomas to prevent infection and malignant degeneration . At CT, cystadenomas present as well-circumscribed unilocular or multilocular low-attenuating cystic masses. The presence of a solid component, enhancing mural nodularity or papillary projections raises suspicion for cystadenocarcinoma. At MR, cystadenomas show similar features to CT but may be better shown to be distinctly separate from the ovary  (Fig. 6).
Cystic RP metastases usually are related to cystic or necrotic RP lymph node spread of disease. The pelvic lymphatics drain directly into the RP with numerous connections to the celiac and mesenteric lymphatics, therefore nearly any intraabdominal tumors could result in metastatic RP lymphadenopathy . Necrotic RP lymphadenopathy most commonly results from a metastatic testicular germ cell tumor in young or middle-aged males  and in females, pelvic malignancies such as ovarian or cervical cancer , Fig. 7. Other tumors which show a propensity to form cystic or necrotic metastatic lymph nodes include lymphoproliferative disorder, papillary thyroid cancer (10–15%), and squamous cell carcinomas of the head and neck [19, 49, 50]. Melanoma has also been documented to result in necrotic lymphadenopathy . Metastatic renal cell carcinoma can also result in RP lymphadenopathy, but cystic necrosis is rare, documented only in case reports . Treated lymphadenopathy can also result in necrosis. For example, in a study by Fulmes et al., lymph node necrosis was described in 70% of patients with treated stage III colorectal cancer ; however, the diagnosis can usually be established in reference to the patients clinical history and prior imaging studies.
Neurogenic tumors are a common cause for RP masses and may show necrosis or cystic change on imaging, which is often difficult to differentiate. A retrospective study of 24 cystic renal masses by Aubert et al. identified the presence of a solid, expansile nodule (5 mm or greater) and irregular, thick walls or septations as features favoring a primary solid lesion having undergone necrosis over a primary cystic lesion ; however, these imaging findings overlap between cystic and necrotic tumors in practice. Genetic syndromes predispose patients to develop particular neurogenic neoplasms, therefore careful review of patient history can be helpful in formulating the differential diagnosis for a cystic RP mass that may represent a neurogenic tumor.
Neurofibromas are encountered in neurofibromatosis (NF) type I, an autosomal dominant disorder affecting up to 1/3000 individuals . Neurofibromas are usually benign peripheral nerve sheath tumors that tend to encase the nerves . Solitary localized neurofibromas can occur sporadically and very rarely show cystic change/myxoid degeneration, whereas plexiform neurofibromas tend to be cystic and are pathognomonic for NF. Plexiform neurofibromas are associated with increased risk of malignant transformation . Within the RP, plexiform neurofibromas are most commonly found along the psoas muscles or presacral regions . At histopathology, neurofibromas have characteristic wavy nuclei and “shredded carrot” type collagen. Plexiform neurofibromas tend to show atypia with hyperchromatic nuclei with “smudgy” chromatin . At CT, RP plexiform neurofibromas classically have the appearance of bilateral, symmetric multilobulated low attenuation masses akin to a “bag of worms” along the distribution of the lumbar plexus. On MR, plexiform neurofibromas have low signal intensity on T1 W and heterogeneously increased signal on T2 W images. Diffuse thickening of the nerves may also be seen . A target appearance or “central dot” sign has been described, consisting of central hypodensity and hyperintense rim peripherally on T2W .
Schwannomas are also usually benign neoplasms of the peripheral nerve sheath Schwann cells, which are associated with both NF types I and II mutations. Malignant transformation is rarer with schwannomas than neurofibromas, but it can occur especially in association with NF type I . Differentiation from neurofibromas is important for treatment considerations. Schwannomas tend to displace the nerve to the side and the nerve can usually be resected without damage to the nerve, whereas resection of neurofibromas often requires nerve grafting to preserve function . Schwannomas are most commonly found in the head and neck, flexor surfaces of the extremities and posterior mediastinum. RP schwannomas account for only 0.3–3.2% of all schwannomas and are particularly prone to necrosis, in which case they are called “ancient schwannoma” because this cystic degeneration is thought to be related to “aging” of the tumor [63, 64]. Due to the capacious nature of the RP, schwannomas can often grow to very large sizes before their incidental discovery. Most are asymptomatic but vague, non-specific symptoms related to mass effect have been reported . At histopathology, spindle cells arranged in a biphasic Antoni A and Antoni B pattern surrounded by a fibrocartilaginous wall can be seen . On imaging, RP schwannomas demonstrate smooth, well-defined borders with common cystic degeneration due to their large size (66% of cases). The presence of calcifications has been described. Schwannomas have been shown to displace adjacent structures without invasion . CT evaluation shows heterogenous contrast enhancement. On MRI, schwannomas tend to be iso- to hypointense on T1 W and hyperintense on T2W images. The solid component enhances post-gadolinium administration, Fig. 8 .
Paragangliomas are neoplasms arising from neural crest cells that are found along the sympathetic chain. Most paragangliomas are solitary, but Multiple Endocrine Neoplasia (MEN) type IIA and IIB are associated with multiple pheochromocytomas and paragangliomas . NF type I is also associated with a slightly higher incidence of paragangliomas . Given that the sympathetic chain runs in close proximity and parallel to the aorta, extra-adrenal paragangliomas can be found in the RP in the prevertebral region, commonly seen arising from a mass of chromaffin cells at the aortic bifurcation referred to as the organ of Zuckerkandl . More than 70% of RP paragangliomas undergo necrosis as they increase in size . Approximately 60% of RP paragangliomas are functioning and secrete catecholamines which may result in hypertension and/or the triad of episodic headaches, diaphoresis, and palpitations . At histopathology, they contain polygonal- or spindle-shaped cells and a rich capillary network . At imaging, close relationship to the aorta, avid peripheral arterial enhancement, and delayed washout are described as characteristic imaging features . At MRI, paragangliomas are heterogeneously hyperintense on T2W, Fig. 9, and have classically been described as being “light-bulb bright,” although this feature has been shown to be neither specific, nor sensitive . Diagnosis is confirmed with functional MIBG nuclear imaging, which is particularly useful in diagnosis of extra-adrenal paragangliomas given that it is a norepinephrine analog .
Neuroblastomas are malignant tumors of undifferentiated sympathetic ganglion cells which have an unpredictable course, with many cases showing spontaneously regression without treatment, and others being very aggressive with up to 50% of patients presenting with metastatic disease . Neuroblastoma is the most common extracranial malignancy in children with 500 new cases diagnosed per year in the United States , very rarely presenting in adulthood with only a few documented case reports. At histology, there is the presence of neuroblasts which are small cells with dark nuclei and very little cytoplasm, arranged in a rosette pattern surrounded by stroma which could be composed of fibrovascular septae or mature derivatives such as ganglion or Schwann cells . At CT, neuroblastomas are heterogenous masses with areas of low attenuation resulting from necrosis and hemorrhage. Calcifications are characteristically present in up to 80–90% of cases. At MRI, neuroblastomas are typically hypointense or of variable on T1W signal (depending on the presence of internal hemorrhage) and hyperintense on T2W with heterogenous enhancement, Fig. 10. Furthermore, MR is the modality of choice for local staging and evaluation of intraspinal extension .
In conclusion, this article reviews the MR imaging appearance of common and uncommon cystic RP common and uncommon cystic RP masses (summarized in Table 2) and presents an approach to formulation of an adequate differential diagnosis using MRI. The normal cisterna chyli may appear dilated and simulate a RP mass; however, the presence of feeding lymphatic channels and delayed enhancement are diagnostic features. Lymphangiomas are the most common RP cystic mass and may show varied appearance; the presence of internal microscopic fat is a specific but an insensitive MRI finding. Other benign and non-aggressive congenital or low-malignant cystic masses may be indistinguishable from RP lymphangioma but are less common or rare. The presence of internal solid enhancing components or suspected cystic change or necrosis in a solid mass should raise the possibility of neurogenic, including parasympathetic ganglia, tumors and, malignancy either from metastatic spread of tumor or from a rare primary RP tumor. If surgical management is not immediately contemplated, patient age, symptoms, history of a genetic syndrome or primary malignancy, and growth on serial imaging studies may help to formulate an imaging differential diagnosis.
Yang DM, Jung DH, Kim H, Kang JH, Kim SH, Kim JH, Hwang HY (2004) Retroperitoneal Cystic Masses: CT, Clinical, and Pathologic Findings and Literature Review. 24 (5):1353–1365. https://doi.org/10.1148/rg.245045017
Bosniak MA (1986) The current radiological approach to renal cysts. 158 (1):1–10. https://doi.org/10.1148/radiology.158.1.3510019
Weekes RG, Berquist TH, McLeod RA, Zimmer WD (1985) Magnetic resonance imaging of soft-tissue tumors: Comparison with computed tomography. Magnetic Resonance Imaging 3 (4):345–352. https://doi.org/10.1016/0730-725X(85)90398-4
Davarpanah AH, Israel GM (2014) MR Imaging of the Kidneys and Adrenal Glands. Radiologic Clinics of North America 52 (4):779–798. https://doi.org/10.1016/j.rcl.2014.02.003
Tirkes T, Sandrasegaran K, Patel AA, Hollar MA, Tejada JG, Tann M, Akisik FM, Lappas JC (2012) Peritoneal and Retroperitoneal Anatomy and Its Relevance for Cross-Sectional Imaging. 32 (2):437–451. https://doi.org/10.1148/rg.322115032
Tirkes T, Sandrasegaran K, Patel AA, Hollar MA, Tejada JG, Tann M, Akisik FM, Lappas JC (2012) Peritoneal and Retroperitoneal Anatomy and Its Relevance for Cross-Sectional Imaging. RadioGraphics 32 (2):437–451. https://doi.org/10.1148/rg.322115032
Pinto PS, Sirlin CB, Andrade-Barreto OA, Brown MA, Mindelzun RE, Mattrey RF (2004) Cisterna Chyli at Routine Abdominal MR Imaging: A Normal Anatomic Structure in the Retrocrural Space. 24 (3):809–817. https://doi.org/10.1148/rg.243035086
Verma SK, Mitchell DG, Bergin D, Lakhman Y, Austin A, Verma M, Assis D, Herrine SK, Parker LJAI (2009) Dilated cisternae chyli: a sign of uncompensated cirrhosis at MR imaging. 34 (2):211–216. https://doi.org/10.1007/s00261-008-9369-7
Gollub MJ, Castellino RA (1996) The cisterna chyli: a potential mimic of retrocrural lymphadenopathy on CT scans. 199 (2):477–480. https://doi.org/10.1148/radiology.199.2.8668798
Primrose JN (1995) Soft tissue tumours. 3rd ed. F. M. Enzinger and S. W. Weiss (eds). 284 × 220 mm. Pp. 1120. Illustrated. 1995. St Louis, Missouri: Mosby-Year-Book. £160. 82 (10):1437–1437. https://doi.org/10.1002/bjs.1800821050
Stoupis C, Ros PR, Abbitt PL, Burton SS, Gauger J (1994) Bubbles in the belly: imaging of cystic mesenteric or omental masses. 14 (4):729–737. https://doi.org/10.1148/radiographics.14.4.7938764
Roisman I, Manny J, Fields S, Shiloni E (1989) Intra-abdominal lymphangioma. 76 (5):485–489. https://doi.org/10.1002/bjs.1800760519
Turki A (2017) Abdominal Cystic Lymphangioma in Adults: Diagnostic Difficulties and Surgical Outcome, vol 04. https://doi.org/10.21767/2254-6758.100066
Ros PR, Olmsted WW, R P Moser J, Dachman AH, Hjermstad BH, Sobin LH (1987) Mesenteric and omental cysts: histologic classification with imaging correlation. 164 (2):327–332. https://doi.org/10.1148/radiology.164.2.3299483
Ayyappan AP, Jhaveri KS, Haider MA (2011) Radiological assessment of mesenteric and retroperitoneal cysts in adults: is there a role for chemical shift MRI? Clinical Imaging 35 (2):127–132. https://doi.org/10.1016/j.clinimag.2010.03.003
Mirsadeghi A, Farrokhi F, Fazli-Shahri A, Gholipour B (2014) Retroperitoneal bronchogenic cyst: a case report. Medical journal of the Islamic Republic of Iran 28:56–56
Govaerts K, Van Eyken P, Verswijvel G, Van der Speeten K (2012) A Bronchogenic Cyst, Presenting as a Retroperitoneal Cystic Mass. 4 (1):37–44. https://doi.org/10.4081/rt.2012.e13
Mehdi G, Maheshwari V, Afzal S, Ansari HA, Ahmad I (2013) Image-guided fine-needle aspiration of retroperitoneal masses: The role of the cytopathologist. Journal of cytology 30 (1):36–41. https://doi.org/10.4103/0970-9371.107511
Üstün M, Risberg B, Davidson B, Berner A (2002) Cystic change in metastatic lymph nodes: A common diagnostic pitfall in fine-needle aspiration cytology. 27 (6):387–392. https://doi.org/10.1002/dc.10201
Gatcombe HG, Assikis V, Kooby D, Johnstone PAS (2004) Primary retroperitoneal teratomas: A review of the literature. Journal of Surgical Oncology 86 (2):107–113. https://doi.org/10.1002/jso.20043
Davidson AJ, Hartman DS, Goldman SM (1989) Mature teratoma of the retroperitoneum: radiologic, pathologic, and clinical correlation. 172 (2):421–425. https://doi.org/10.1148/radiology.172.2.2664866
Panageas E (1991) General diagnosis case of the day. Primary retroperitoneal teratoma. American Journal of Roentgenology 156 (6):1292–1294. https://doi.org/10.2214/ajr.156.6.2028883
Bruneton JN, Diard F, Drouillard JP, Sabatier JC, Tavernier JF (1980) Primary retroperitoneal teratoma in adults: presentation of two cases and review of the literature. 134 (3):613–616. https://doi.org/10.1148/radiology.134.3.7355206
Outwater EK, Siegelman ES, Hunt JL (2001) Ovarian Teratomas: Tumor Types and Imaging Characteristics. 21 (2):475–490. https://doi.org/10.1148/radiographics.21.2.g01mr09475
Sato F, Mimata H, Mori K (2010) Primary retroperitoneal mature cystic teratoma presenting as an adrenal tumor in an adult. International Journal of Urology 17 (9):817–817. https://doi.org/10.1111/j.1442-2042.2010.02591.x
Uchihashi K, Matsuyama A, Shiba E, Kimura Y, Ogata T, Yabuki K, Harada H, Kubo C, Tsuda Y, Jotatsu M, Hisaoka M (2017) Retroperitoneal dedifferentiated liposarcoma with huge cystic degeneration: A case report. 67 (5):264–268. https://doi.org/10.1111/pin.12525
Sahin H, Abdullazade S, Sanci M (2017) Mature cystic teratoma of the ovary: a cutting edge overview on imaging features. Insights into imaging 8 (2):227–241. https://doi.org/10.1007/s13244-016-0539-9
Craig WD, Fanburg-Smith JC, Henry LR, Guerrero R, Barton JH (2009) Fat-containing Lesions of the Retroperitoneum: Radiologic-Pathologic Correlation. RadioGraphics 29 (1):261–290. https://doi.org/10.1148/rg.291085203
Manjón CC, Sánchez ÁT, Lara JDP, Martínez Silva V, Betriu GC, Sánchez AR, Peñalver CG, Galvis ÓL (2003) Retroperitoneal Abscesses. Scandinavian Journal of Urology and Nephrology 37 (2):139–144. https://doi.org/10.1080/00365590310008884
Singh K, Wang ML, Ofori E, Widmann W, Alemi A, Nakaska M (2012) Gallstone abscess as a result of dropped gallstones during laparoscopic cholecystectomy. International journal of surgery case reports 3 (12):611–613. https://doi.org/10.1016/j.ijscr.2012.07.017
Federle MP, Jeffrey RB, Crass RA, Van Dalsem V (1981) Computed tomography of pancreatic abscesses. American Journal of Roentgenology 136 (5):879–882. https://doi.org/10.2214/ajr.136.5.879
Mavilia MG, Molina M, Wu GY (2016) The Evolving Nature of Hepatic Abscess: A Review. J Clin Transl Hepatol 4 (2):158–168. https://doi.org/10.14218/jcth.2016.00004
Daly KP, Ho CP, Persson DL, Gay SB (2008) Traumatic Retroperitoneal Injuries: Review of Multidetector CT Findings. RadioGraphics 28 (6):1571–1590. https://doi.org/10.1148/rg.286075141
Killeen KL, DeMeo JH, Cole TJ (1999) Computed tomography of traumatic and nontraumatic retroperitoneal emergencies. Emergency Radiology 6 (4):232–243. https://doi.org/10.1007/s101400050057
Hahn PF, Saini S, Stark DD, Papanicolaou N, Ferrucci JT (1987) Intraabdominal hematoma: the concentric-ring sign in MR imaging. American Journal of Roentgenology 148 (1):115–119. https://doi.org/10.2214/ajr.148.1.115
Mingoli A, Cavallaro A, Sapienza P, Di Marzo L, Feldhaus RJ, Cavallari N (1996) International registry of inferior vena cava leiomyosarcoma: analysis of a world series on 218 patients. Anticancer research 16 (5b):3201–3205
Bruyninckx CMA, Derksen OS (1986) Leiomyosarcoma of the inferior vena cava: Case report and review of the literature. Journal of Vascular Surgery 3 (4):652–656. https://doi.org/10.1016/0741-5214(86)90292-2
Hashimoto H, Tsuneyoshi M, Enjoji M (1985) Malignant smooth muscle tumors of the retroperitoneum and mesentery: A clinicopathologic analysis of 44 cases. 28 (3):177–186. https://doi.org/10.1002/jso.2930280307
Hemant D, Krantikumar R, Amita J, Chawla A, Ranjeet N (2001) Primary leiomyosarcoma of inferior vena cava, a rare entity: Imaging features. 45 (4):448–451. https://doi.org/10.1046/j.1440-1673.2001.00955.x
Navin P, Meshkat B, McHugh S, Beegan C, Leen E, Prins H, Aly S (2012) Primary retroperitoneal mucinous cystadenoma—A case study and review of the literature. International Journal of Surgery Case Reports 3 (10):486–488. https://doi.org/10.1016/j.ijscr.2012.05.010
Shanbhogue AK, Fasih N, Macdonald DB, Sheikh AM, Menias CO, Prasad SR (2012) Uncommon Primary Pelvic Retroperitoneal Masses in Adults: A Pattern-based Imaging Approach. 32 (3):795–817. https://doi.org/10.1148/rg.323115020
Arribas D, Cay A, Latorre A, Córdoba E, Martínez F, Lagos JJAoG, Obstetrics (2004) Retroperitoneal mucinous cystadenoma. 270 (4):292–293. https://doi.org/10.1007/s00404-003-0515-8
Min BW, Kim JM, Um JW, Lee ES, Son GS, Kim SJ, Moon HY (2004) The First Case of Primary Retroperitoneal Mucinous Cystadenoma in Korea: A Case Report. Korean J Intern Med 19 (4):282–284. https://doi.org/10.3904/kjim.2004.19.4.282
Yan S-L, Lin H, Kuo C-L, Wu H-S, Huang M-H, Lee Y-T (2008) Primary retroperitoneal mucinous cystadenoma: Report of a case and review of the literature. World journal of gastroenterology 14 (37):5769–5772. https://doi.org/10.3748/wjg.14.5769
Lai ECH, Chung KM, Lau WY (2006) Primary retroperitoneal mucinous cystadenoma. ANZ Journal of Surgery 76 (6):537–537. https://doi.org/10.1111/j.1445-2197.2006.03768.x
Einstein DM, Singer AA, Chilcote WA, Desai RK (1991) Abdominal lymphadenopathy: spectrum of CT findings. 11 (3):457–472. https://doi.org/10.1148/radiographics.11.3.1852937
Scatarige JC, Fishman EK, Kuhajda FP, Taylor GA, Siegelman SS (1983) Low attenuation nodal metastases in testicular carcinoma. Journal of computer assisted tomography 7 (4):682–687
Park JM, Charnsangavej C, Yoshimitsu K, Herron DH, Robinson TJ, Wallace S (1994) Pathways of nodal metastasis from pelvic tumors: CT demonstration. 14 (6):1309–1321. https://doi.org/10.1148/radiographics.14.6.7855343
Glazer HS, Siegel MJ, Sagel SS (1989) Low-attenuation mediastinal masses on CT. American Journal of Roentgenology 152 (6):1173–1177. https://doi.org/10.2214/ajr.152.6.1173
Som PM (1987) Lymph nodes of the neck. 165 (3):593–600. https://doi.org/10.1148/radiology.165.3.3317494
Ishii N, Yonese J, Tsukamoto T, Maezawa T, Ishikawa Y, Fukui I (2001) Retroperitoneal cystic metastasis from a small clear cell renal carcinoma. 8 (11):637–639. https://doi.org/10.1046/j.1442-2042.2001.00385.x
Fulmes M, Setrakian S, Raj PK, Bogard BM (2005) Cancer biology and necrotic changes in metastatic lymph nodes and survival of colon cancer patients. The American Journal of Surgery 189 (3):364-368. https://doi.org/10.1016/j.amjsurg.2004.11.028
Aubert S, Zini L, Delomez J, Biserte J, Lemaitre L, Leroy X (2005) Cystic Renal Cell Carcinomas In Adults. Is Preoperative Recognition Of Multilocular Cystic Renal Cell Carcinoma Possible? 174 (6):2115–2119. https://doi.org/10.1097/01.ju.0000181210.72528.ab
Huson SM, Compston DA, Clark P, Harper PS (1989) A genetic study of von Recklinghausen neurofibromatosis in south east Wales I Prevalence, fitness, mutation rate, and effect of parental transmission on severity. Journal of Medical Genetics 26 (11):704–711. https://doi.org/10.1136/jmg.26.11.704
Tsai C-J (1994) Unusual ultrasonographic appearance of a solitary retroperitoneal neurofibroma. 67 (794):210–211. https://doi.org/10.1259/0007-1285-67-794-210
Murphey MD, Smith WS, Smith SE, Kransdorf MJ, Temple HT (1999) Imaging of Musculoskeletal Neurogenic Tumors: Radiologic-Pathologic Correlation. 19 (5):1253–1280. https://doi.org/10.1148/radiographics.19.5.g99se101253
Bass JC, Korobkin M, Francis IR, Ellis JH, Cohan RH (1994) Retroperitoneal plexiform neurofibromas: CT findings. American Journal of Roentgenology 163 (3):617–620. https://doi.org/10.2214/ajr.163.3.8079855
Rodriguez FJ, Folpe AL, Giannini C, Perry A (2012) Pathology of peripheral nerve sheath tumors: diagnostic overview and update on selected diagnostic problems. Acta neuropathologica 123 (3):295–319. https://doi.org/10.1007/s00401-012-0954-z
Lin J, Martel W (2001) Cross-Sectional Imaging of Peripheral Nerve Sheath Tumors. American Journal of Roentgenology 176 (1):75–82. https://doi.org/10.2214/ajr.176.1.1760075
Bhargava R, Parham DM, Lasater OE, Chari RS, Chen G, Fletcher BDJPR (1997) MR imaging differentiation of benign and malignant peripheral nerve sheath tumors: use of the target sign. 27 (2):124–129. https://doi.org/10.1007/s002470050082
Ghosh BC, Ghosh L, Huvos AG, Fortner JG (1973) Malignant schwannoma. A Clinicopathologic Study. 31 (1):184-190. https://doi.org/10.1002/1097-0142(197301)31:1%3c184::aid-cncr2820310126%3e3.0.co;2-8
Tsai W-C, Chiou H-J, Chou Y-H, Wang H-K, Chiou S-Y, Chang C-Y (2008) Differentiation Between Schwannomas and Neurofibromas in the Extremities and Superficial Body. 27 (2):161–166. https://doi.org/10.7863/jum.2008.27.2.161
Schindler OS, Dixon JH, Case P (2002) Retroperitoneal Giant Schwannomas: Report on Two Cases and Review of the Literature. 10 (1):77–84. https://doi.org/10.1177/230949900201000114
Shilpa B (2012) Ancient schwannoma-a rare case. Ethiop J Health Sci 22 (3):215–218
Hoarau N, Slim K, Da Ines D (2013) CT and MR imaging of retroperitoneal schwannoma. Diagnostic and Interventional Imaging 94 (11):1133–1139. https://doi.org/10.1016/j.diii.2013.06.002
Narasimha A, Kumar MH, Kalyani R, Madan M (2010) Retroperitoneal cystic schwannoma: A case report with review of literature. Journal of cytology 27 (4):136–139. https://doi.org/10.4103/0970-9371.73299
Hughes MJ, Thomas JM, Fisher C, Moskovic EC (2005) Imaging features of retroperitoneal and pelvic schwannomas. Clinical Radiology 60 (8):886–893. https://doi.org/10.1016/j.crad.2005.01.016
Tanaka Y, Soeda S, Huppert P, Claussen CD (1999) MR Findings in Primary Retroperitoneal Schwannoma AU - Hayasaka, K. Acta Radiologica 40 (1):78–82. https://doi.org/10.1080/02841859909174408
Wasserman PG, Savargaonkar P (2001) Paragangliomas: Classification, pathology, and differential diagnosis. Otolaryngologic Clinics of North America 34 (5):845–862. https://doi.org/10.1016/S0030-6665(05)70351-0
Tate JM, Gyorffy JB, Colburn JA (2017) The importance of pheochromocytoma case detection in patients with neurofibromatosis type 1: A case report and review of literature. SAGE Open Med Case Rep 5:2050313X17741016–12050313X17741016. https://doi.org/10.1177/2050313x17741016
Gill T, Adler K, Schrader A, Desai K, Wermers J, Beteselassie N (2017) Extra-adrenal pheochromocytoma at the organ of Zuckerkandl: a case report and literature review. Radiology case reports 12 (2):343–347. https://doi.org/10.1016/j.radcr.2016.12.009
Shen Y, Zhong Y, Wang H, Ma L, Wang Y, Zhang K, Sun Z, Ye H (2018) MR imaging features of benign retroperitoneal paragangliomas and schwannomas. BMC neurology 18 (1):1–1. https://doi.org/10.1186/s12883-017-0998-8
Ji X-K, Zheng X-W, Wu X-L, Yu Z-P, Shan Y-F, Zhang Q-Y, Zeng Q-Q (2017) Diagnosis and surgical treatment of retroperitoneal paraganglioma: A single-institution experience of 34 cases. Oncology letters 14 (2):2268–2280. https://doi.org/10.3892/ol.2017.6468
Hayes WS, Davidson AJ, Grimley PM, Hartman DS (1990) Extraadrenal retroperitoneal paraganglioma: clinical, pathologic, and CT findings. American Journal of Roentgenology 155 (6):1247–1250. https://doi.org/10.2214/ajr.155.6.2173385
Elsayes KM, Narra VR, Leyendecker JR, Francis IR, Lewis JS, Brown JJ (2005) MRI of Adrenal and Extraadrenal Pheochromocytoma. American Journal of Roentgenology 184 (3):86–867. https://doi.org/10.2214/ajr.184.3.01840860
Leung K, Stamm M, Raja A, Low G (2013) Pheochromocytoma: The Range of Appearances on Ultrasound, CT, MRI, and Functional Imaging. American Journal of Roentgenology 200 (2):370-378. https://doi.org/10.2214/ajr.12.9126
Øra I, Eggert A (2011) Progress in treatment and risk stratification of neuroblastoma: Impact on future clinical and basic research. Seminars in Cancer Biology 21 (4):217–228. https://doi.org/10.1016/j.semcancer.2011.07.002
Ishola TA, Chung DH (2007) Neuroblastoma. Surgical Oncology 16 (3):149–156. https://doi.org/10.1016/j.suronc.2007.09.005
Lonergan GJ, Schwab CM, Suarez ES, Carlson CL (2002) Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics 22 (4):911–934. https://doi.org/10.1148/radiographics.22.4.g02jl15911
Conflict of interest
The authors declare that they have no conflict of interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Nguyen, K., Siegelman, E.S., Tu, W. et al. Update on MR Imaging of cystic retroperitoneal masses. Abdom Radiol 45, 3172–3183 (2020). https://doi.org/10.1007/s00261-019-02196-9
- Magnetic Resonance Imaging MRI