Uncommon primary pelvic retroperitoneal masses in adults: a pattern-based imaging approach

Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?

OBJECTIVES

Early, accurate diagnosis is crucial for the prognosis of patients with soft tissue sarcomas. To this end, standardization of imaging algorithms, technical requirements, and reporting is therefore a prerequisite. Since the first European Society of Musculoskeletal Radiology (ESSR) consensus in 2015, technical achievements, further insights into specific entities, and the revised WHO-classification (2020) and AJCC staging system (2017) made an update necessary. The guidelines are intended to support radiologists in their decision-making and contribute to interdisciplinary tumor board discussions.

MATERIALS AND METHODS

A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements were scored online by level of agreement (0 to 10) during two iterative rounds. Either "group consensus," "group agreement," or "lack of agreement" was achieved.

RESULTS

Eight sections were defined that finally contained 145 statements with comments. Overall, group consensus was reached in 95.9%, and group agreement in 4.1%. This communication contains the first part consisting of the imaging algorithm for suspected soft tissue tumors, methods for local imaging, and the role of tumor centers.

CONCLUSION

Ultrasound represents the initial triage imaging modality for accessible and small tumors. MRI is the modality of choice for the characterization and local staging of most soft tissue tumors. CT is indicated in special situations. In suspicious or likely malignant tumors, a specialist tumor center should be contacted for referral or teleradiologic second opinion. This should be done before performing a biopsy, without exception.

CLINICAL RELEVANCE

The updated ESSR soft tissue tumor imaging guidelines aim to provide best practice expert consensus for standardized imaging, to support radiologists in their decision-making, and to improve examination comparability both in individual patients and in future studies on individualized strategies.

KEY POINTS

• Ultrasound remains the best initial triage imaging modality for accessible and small suspected soft tissue tumors. • MRI is the modality of choice for the characterization and local staging of soft tissue tumors in most cases; CT is indicated in special situations. Suspicious or likely malignant tumors should undergo biopsy. • In patients with large, indeterminate or suspicious tumors, a tumor reference center should be contacted for referral or teleradiologic second opinion; this must be done before a biopsy.

Surgical Treatment of a Large Post-cesarean Hematoma in the Retzius Space Accompanied by a Blood Coagulation Disorder: A Rare Case Report

Hematoma in the Retzius space after a cesarean section is a rare complication. The Retzius space, also referred to as the prevesical or retropubic space, represents an extraperitoneal artificial cavity situated between the pubic symphysis and the bladder. In instances where conservative treatment involving vigilant monitoring along with analgesics and antibiotics or ultrasound-guided percutaneous puncture proves unsuccessful, re-operation becomes imperative. Our case report concerns a second-parity pregnant patient who underwent a cesarean section in the 39th gestational week. A decrease in hemoglobin level on the third postoperative day, combined with the onset of febrile infection, an increase in inflammatory markers, and the manifestation of lower abdominal pain, prompted a thorough investigation of the puerperant. Imaging revealed the existence of a hematoma in the Retzius space associated with a mild blood coagulation disorder. Subsequently, the unsuccessful outcome of the ultrasound-guided percutaneous puncture of the hematoma, combined with the persistence of clinico-laboratory findings, led to the decision to perform a re-laparotomy on the 10th postoperative day after the cesarean section. During the surgery, a large hematoma was identified in the Retzius space, extending below the rectus abdominis muscles. The procedure involved surgical drainage of the hematoma, meticulous hemostasis, and the placement of negative pressure drainage in the Retzius space. The patient was discharged from the clinic on the fifth postoperative day after re-operation. Ten days later, both blood tests and ultrasounds were without abnormal findings. In this paper, following the case presentation, a brief review is provided regarding the diagnostic and therapeutic approach of patients with hematoma in the Retzius space after cesarean section.

Arteriovenous Malformation Associated with Intravenous Leiomyomatosis of the Uterus: Characteristic CT Findings and Treatment by Embolization and Surgery

Seven consecutive female patients with pathologically confirmed arteriovenous malformation (AVM) with intravenous leiomyomatosis (IVL) of the uterus (age range, 32-61 years; mean age, 43 years) treated between 2005 and 2021 from a single institution were reviewed. Computed tomography (CT) findings of congenital pelvic AVM of 10 female patients were compared with those of AVM with IVL. Characteristic CT findings of AVM with IVL revealed a focal soft tissue mass inside a dilated venous structure of the AVM. Multiple sessions of transvenous coil embolization of the AVM with or without the injection of ethanol were performed. After complete (6/7, 86%) or partial (1/7, 14%) embolization of the AVM, complete surgical resection of the IVL and embolized AVM mass was performed in 4 patients. Patients with lung metastasis or residual embolized AVM masses are under follow-up with antiestrogen hormonal therapy.

Malignant pelvic paraganglioma: A case report

Pheochromocytomas arising from outside the adrenal glands are called paragangliomas and constitute a rare disease and can occur in the pelvic retroperitoneum. Symptoms of excess catecholamine production, as well as elevated urine vanillylmandelic acid levels and serum and urine norepinephrine levels, are highly diagnostic for paraganglioma. Imaging can be helpful for the diagnostic of these pelvic tumors, differentiating them from other pelvic masses. We hereby present a case of pelvic malignant paraganglioma.

Rare Mesenchymal Tumors of the Pelvis: Imaging and Pathologic Correlation

Most pelvic tumors originate from the organs. Less commonly, tumors can arise from the various anatomic pelvic compartments and are comprised of mesenchymal tissue: muscles, connective tissue, vessels, lymphatics, and fat. Among some of the rarer entities are benign tumors (eg, angiomyxoma, cellular angiofibroma, and desmoid fibromatosis), malignant tumors (eg, sarcoma), and tumors that can manifest as benign or malignant (eg, solitary fibrous tumor or nerve sheath tumor). Because these tumors are uncommon and often manifest with nonspecific clinical features, imaging (usually MRI) is an initial step in the evaluation. Radiologists interpreting these images are asked to help narrow the differential diagnosis and assess the likelihood of malignancy for treatment planning. Thus, the MRI report should include the imaging features that would indicate the underlying tissue histology for pathologic diagnosis as well as a description of the anatomic extent and pattern of growth. The authors describe multiple locally aggressive benign and malignant mesenchymal tumors and highlight characteristic clinical and imaging features that enable the radiologist to narrow the differential diagnosis. The anatomic spaces of the pelvis are reviewed with illustrations to aid the radiologist in describing these tumors, which often span multiple pelvic compartments. Tumor appearance at T2-weighted, diffusion-weighted, and postcontrast MRI is summarized and illustrated with correlation at CT or fluorodeoxyglucose PET/CT, when available. MRI features that correspond to specific types of tissue (eg, myxoid, fibrous, or vascular) are highlighted and correlated with images from pathologic evaluation. Online supplemental material is available for this article. ^©RSNA, 2021.

Epidemiology, diagnostic approach and therapeutic management of tailgut cysts: A systematic review

BACKGROUND

Tailgut cysts (TGCs) are benign congenital abnormalities that usually present with non-specific symptoms, constituting a diagnostic dilemma for physicians. The aim of this study was to systematically review the literature concerning clinical manifestations, diagnostic modalities and histologic findings of TGCs and highlight current knowledge on therapeutic management of this rare entity.

METHODS

PubMed and Embase databases were systematically searched by two independent investigators (last search 18 February 2021) for studies concerning TGCs published in the past two decades.

RESULTS

Totally, 144 articles, including 135 case reports and 9 case series, met our inclusion criteria. One hundred eighty-four patients were included (3:1/female:male) with an age of 42.3 ± 18.7 years (mean, SD), while 5 cases concerned new-born infants. Pain was the prevailing clinical manifestation (41.8%), whereas 16.8% were asymptomatic. MRI and CT were utilized for diagnosis in 58.7% and 54.7% of cases, respectively. The majority of cysts were multilocular, while ciliated columnar epithelium and smooth muscles of the cyst wall were the prevailed histological findings. Malignant degeneration of TGCs was reported in 32.1% of cases, while carcinoid tumours were the most frequent malignancies. Surgical resection was performed in 155 cases, while laparoscopic and robotic approach was preferred in 18 and 2 cases, respectively. A posterior approach was implemented in 80.9%, anterior technique in 9% and combined technique in 6.7% of cases. Postoperative complications and recurrence of the cystic lesion were reported in 17.4% and 7.6% of cases, respectively.

CONCLUSIONS

TGCs constitute a dilemma for the physicians. Surgical resection comprises the ultimate treatment to avoid complications or malignant transformation of the cyst. Concrete follow-up strategies and optimal therapeutic options should be outlined through consensus guidelines and at the time being, such decisions can be made only on the basis of extrapolation and on a case-by-case approach.

Adrenal pheochromocytoma: is it all or the tip of the iceberg?

Adrenal pheochromocytoma is not always a simple retroperitoneal tumor but may be part of a more complicated condition. It often has a spectrum of complex and variable imaging features, may present as a collision tumor and composite tumor, and is associated with a variety of clinical syndromes. A comprehensive understanding of the clinical, pathological, and variable imaging manifestations of pheochromocytoma can help radiologists make an accurate diagnosis. This article reviews various special imaging features of pheochromocytoma and pheochromocytoma-related diseases.

Radiologic-Pathologic Correlation of Primary Retroperitoneal Neoplasms

An earlier incorrect version of this article appeared in print. The online version is correct.

Giant retroperitoneal myxoma: A case report and literature review

INTRODUCTION AND IMPORTANCE

Myxoma is a benign tumor and is mesenchymal in origin. Myxomas of the retroperitoneum are extremely rare entities.

CASE PRESENTATION

We here report a case of a 67-year-old male who presented with progressive abdominal distention for 3 years. Laboratory investigations revealed a reduction in erythrocytes, lymphocytes, hemoglobin, and an elevation in carbohydrate antigen 19-9. Imaging findings showed a multilocular cystic mass in the right abdomen with thin septa and internal calcifications. Laparotomy revealed that the mass had arisen from the retroperitoneum and the histological study suggested the diagnosis of myxoma.

DISCUSSION

Myxoma features as a "cystic mass" in imaging studies. Therefore, the possibility of a cystic lymphangioma, cystic mesothelioma and myxoma should be considered when a multicystic lesion in the retroperitoneal space is observed. Due to the rarity of retroperitoneal myxomas and lack of specific manifestations and diagnostic methods, preoperative diagnosis is often delayed or incorrect. And until now, only a few cases of retroperitoneal myxoma have been reported.

CONCLUSION

The report will increase the understanding of the diagnosis and treatment of retroperitoneal myxomas. A brief review of the related literature was also carried out.

[Multicentric Florid Cystic Endosalpingiosis in Different Anatomical Spaces: A Case Report]

Endosalpingiosis is a condition that causes the non-neoplastic proliferation of ectopic tubal epithelium. Florid cystic endosalpingiosis is an atypical subtype that is very rarely reported. It presents as a mass-like feature and therefore needs to be differentiated from tumorous conditions. Here, we report the imaging findings of a case of multicentric florid cystic endosalpingiosis in the extraperitoneal pelvic cavity and the retroperitoneal spaces.

Huge pelvic retroperitoneal cyst masquerading as hydrosalpinx: A case report with review of the literature

Primary retroperitoneal cysts (RPCs) are a rare surgical entity and are mostly detected incidentally. Usually, they are asymptomatic. At times, they may attain a huge size and may present with a large abdominal lump. Often, they pose a dilemma at diagnosis and for management. Though the laparoscopic approach has been described for their surgical excision, open surgery is still the preferred approach. We herein present a case of a voluminous retroperitoneal pelvic cystic mass in a 40-year-old female, which was diagnosed as hydrosalpinx on a magnetic resonance imaging scan. The patient was referred to us by the specialist in gynecologic laparoscopy after the incidental discovery of the RPC during his surgical intervention, purportedly for large hydrosalpinx. At our hospital, 4 days after the above intervention, she underwent laparoscopic complete excision of the cyst. Her postoperative recovery was uneventful and she was discharged on postoperative day 3 without any complications. Histopathology was suggestive of Mullerian inclusion cyst. This case report aims to share a rare case of a large primary retroperitoneal pelvic cystic lesion, which caused a diagnostic challenge preoperatively but was eventually managed successfully, laparoscopically.

Update on MR Imaging of cystic retroperitoneal masses

OBJECTIVE

This article reviews the MRI appearance of cystic retroperitoneal (RP) masses.

CONCLUSION

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.

Lumbosacral plexiform neurofibroma: a rare case in an adult without neurofibromatosis type I

Plexiform neurofibromas are an uncommon variant of neurofibromas that are described as being essentially pathognomonic of neurofibromatosis type 1 (NF1). Plexiform neurofibromas in the absence of NF1 are extremely rare. We present the case of a 38-year-old woman with a large multilobulated lumbosacral mass extending into the pelvis and proximal thigh. Histopathology of a CT-guided biopsy of the mass revealed it to be a neurofibroma. The imaging findings were consistent with a plexiform subtype. Further imaging and clinical workup showed that the patient had no other identifiable neurofibromas and did not meet criteria for the diagnosis of NF1.

Retroperitoneal cystic masses: magnetic resonance imaging features

The objective of this review is to discuss the clinical and histopathologic features, MRI characteristics, and management options of retroperitoneal cystic masses. Radiologists should be familiar with the MR imaging characteristics of retroperitoneal cystic masses to allow for a refined differential diagnosis, assist with lesion management, and prevent unnecessary invasive procedures.

Giant Melanotic Malignant Peripheral Nerve Sheath Tumor in the Pelvis: Contrast-Enhanced CT and 18F-FDG PET/CT Finding

Melanotic malignant peripheral nerve sheath tumor is an extremely rare tumor, which originates from the neural crest, and more than half the cases are associated with Carney complex (myxomas, spotty pigmentation, and endocrine abnormalities). Herein, we have presented a case of a melanotic malignant peripheral nerve sheath tumor, which is not associated with Carney complex. The patient underwent preoperative nonenhanced CT, contrast-enhanced CT, and F-FDG PET/CT scans, which showed a large pelvic tumor with heterogeneous enhancement and increased F-FDG uptake. Subsequently, the patient underwent complete resection of the tumor.

Giant Primary Retroperitoneal Serous Cystadenoma: A Rare Entity Mimicking Multiple Neoplastic and Nonneoplastic Processes

Serous cystadenoma, often known as ovarian serous cystadenoma, is one of the common benign ovarian neoplasms. On the other hand, primary retroperitoneal serous cystadenoma is an extremely rare benign entity whose pathogenesis has not been well understood. Clinical presentation and symptomatology vary greatly and are highly dependent on the size and location of the lesion. Primary retroperitoneal serous cystadenomas are homogeneous, unilocular, thin-walled cystic masses. If they grow large enough, they tend to compress and deform adjacent organs, giving clinicians a misimpression of malignant pattern of behavior. Therefore, it is crucial to differentiate benign primary retroperitoneal serous cystadenomas from other epithelial and nonepithelial cystic lesions or masses involving retroperitoneal regions. Management-wise, complete cyst excision without rupture or spillage of the cyst contents is the recommended therapeutic method for primary retroperitoneal serous cystadenomas. This review will highlight the current knowledge on its pathogenesis and discuss its histopathologic features and differential diagnoses from the pathologist's point of view.

A rare solitary fibrous tumor in the ischiorectal fossa: a case report

Background

A solitary fibrous tumor (SFT) is a rare mesenchymal tumor that occurs mostly in pleural sites, and an SFT occurring in the ischiorectal fossa is extremely rare. Because of the rarity, there are few reports detailing an SFT in the ischiorectal fossa.

Case presentation

A pararectal tumor was incidentally found in a 42-year-old man during a routine medical examination. The patient had no symptoms and no previous medical history. In the physical examination, a smooth-margined and hard elastic mass was felt, and in a digital rectal examination, the rectal mucosa appeared normal. A computed tomography (CT) scan showed a 5-cm, well-defined, solid mass in the left ischiorectal fossa. Contrast-enhanced CT in the early phase showed intense heterogeneous enhancement that persisted during the delayed phase. T2-weighted images of magnetic resonance imaging yielded heterogeneous intermediate and low signal intensity. Intense arterial enhancement suggested a hypervascular nature, and persistent delayed enhancement and low signal bands on T2-weighted images suggested a fibrous component of the mass. An SFT was suspected. Most SFTs are benign but have malignant potential. Our patient did not hope for surgery if the tumor was benign; therefore, an ultrasound-guided transperineal core needle biopsy was performed to decide on a treatment strategy. Microscopic examination showed tumor cells appearing as spindle and fibroblast-like cells within a collagenous stroma. Immunohistochemistry identified CD34 and vimentin, supporting the diagnosis of an SFT. The patient consented to excision of the mass. He was placed in a prone jackknife position, and the tumor was removed transperineally using a posterior approach (modified Kraske procedure). The levator ani muscle, external sphincter muscles, and rectum were not involved and separated from the tumor. The tumor was successfully resected en bloc with no complications. Five uneventful days post surgery, the patient was discharged. There was no local recurrence during the year following surgery.

Conclusion

Imaging findings reflect the tissue characterization such as hypervascularity and fibrous nature of SFTs. We have presented a rare case of an SFT in the ischiorectal fossa with useful imaging findings for diagnosis, treatment strategy, and successful surgical removal using a posterior approach.

Case report: Laparoscopic approach in the treatment of presacral lipoma

Retrorectal lipoma, as well as other retrorectal tumours, is a relatively rare disorder. Retrorectal tumours accounted for 1 in 40,000 hospital admissions. We present a case of retrorectal lipoma, 15 cm × 10 cm × 8 cm in size, treated by the laparoscopic approach. The preoperative magnetic resonance imaging visualised a mass, 12 cm × 6.7 cm × 8.6 cm in diameter, in the retrorectal space, spreading toward the left obturator foramen. Surgery was indicated due to exclude malignant process certainly, because it is difficult to differentiate lipoma from low-grade liposarcoma on non invasive imaging. Laparoscopic extirpation of the tumour was performed. The overall operative time was 80 min. The diagnosis of lipoma was established on histological examination. The patient was discharged from hospital on the 2nd day after the surgery. We have found this minimally invasive operation to be an effective and well-tolerated treatment option, determined by the experience of the surgeon.

Pelvic epidermoid cyst: A rare cause of lower urinary tract symptoms

Pelvic retroperitoneum is a bizarre location of an epidermoid cyst and obstructive voiding caused by it even being stranger. Voiding symptoms related to such an abnormal location of cyst are extremely rare and literature that taps into such cases is scarce. We are presenting here a case of 26-year-old man who was presented with obstructive lower urinary tract symptoms and chronic constipation. On evaluation, he was found to have well-defined cyst in pelvic retroperitoneum. Complete excision of the cyst was done; histopathology confirmed it as an epidermoid cyst. His symptoms were completely relieved over a 12-month follow-up.

A rare case of extra-adrenal bilateral perirenal and periureteric myelolipoma

A 30-year-old immunocompetent female presented with right flank pain since 3 years. MRI revealed a large well-defined T1 and T2 hypointense mildly enhancing lesion in the right anterior pararenal space displacing the right kidney and encasing the right ureter with T2 hyperintense wall thickening of the left renal pelvis and ureter. A provisional diagnosis of solitary fibrous tumour was kept. Bilateral double J stenting was done for hydronephrosis. Surgical debulking of the lesion was done with biopsy from the left periureteral wall thickening and was found to be myelolipoma on histopathological examination. This case is a novel variety of myelolipoma which is lipid poor, extra-adrenal and in bilateral perirenal and periureteric location.

A Giant Primary Retroperitoneal Serous Cystadenoma: Case Report and Review of Retroperitoneal Cysts

Primary retroperitoneal serous cystadenomas (PRSCs) are rare cystic lesions whose pathogenesis is currently not well understood. Although the vast majority of tumors are benign, early recognition and resection is necessary to avoid malignant transformation, rupture, and secondary infection. Here we present the case of a 79-year-old woman who presented with confusion, visual hallucinations, and a history of fall. As part of the work-up for abdominal distension, computed tomography scan of the abdomen and pelvis was performed, which revealed a right-sided retroperitoneal cystic lesion measuring 26.6 × 16.7 cm in size. The lesion was resected laparoscopically, and the surgical specimen measured 28 × 17 cm. Histology revealed a serous cystadenoma. The postsurgical course was uneventful, and no radiological recurrence was noted on 3 months follow-up. Very few primary retroperitoneal cystic lesions have been reported in the literature. Most lesions are benign and predominantly occur in females. They may remain asymptomatic for long periods of time and are usually discovered when they reach very large in size. In rare cases, these lesions may have malignant potential. Diagnosis of PRSC should be considered in the differential diagnosis of all retroperitoneal cysts.

Susceptibility Weighted With Quantitative Phase Magnetic Resonance Imaging in Differentiation of Various Stages of Hemorrhage and Calcification in Female Pelvic Pathologies: A Preliminary Study

BACKGROUND

The purposes of this study were to assess the value of phase for characterization of female pelvic lesions with hemorrhage in various stages and to differentiate them from calcified lesions at 3.0-T magnetic resonance imaging (MRI).

METHODS

Forty-four female patients with hemorrhagic (n = 37) or calcified (n = 7) pelvic pathology underwent conventional MRI including susceptibility-weighted imaging with phase information. Hemorrhagic lesions were grouped into acute, subacute, and chronic, and calcified lesions were detected on the basis of conventional imaging findings. Phase quantification of these hemorrhagic and calcified lesions was performed.

RESULTS

The phase values significantly differed (P < 0.001) among various stages of hemorrhage, as well as calcification (chronic hemorrhage, -65.09 ± 9.09 degrees; subacute hemorrhage, -11.41 ± 4.4 degrees; acute hemorrhage, -42.30 ± 5.20 degrees; and calcified lesions, 117.55 ± 12.93 degrees).

CONCLUSIONS

Quantitative phase imaging has the potential to differentiate various stages of hemorrhagic and calcified pathologies. This may add value to the conventional MRI in improved characterization of these entities in female pelvic pathologies.

Imaging Diagnosis of a Rare Presacral Tumour

Background

Primary tumors in the presacral (retrorectal) space are extremely rare in adults, with an estimated incidence of 0.0025 to 0.014 in large referral centers. Congenital varieties are most common and comprise two thirds of these tumors. Primary retroperitoneal sarcomas in the pelvic region are extremely rare. We report the ultrasound and the corresponding Computed Tomography (CT) features of a rare presacral fibrosarcoma in an adult woman, in whom the diagnosis was confirmed by a CT-guided biopsy.

Case Report

A 54-year-old woman presented with a history of lumbar and perineal pain and painful defecation. Rectal examination revealed a hard mass in the retrorectal space. The patient was referred for imaging and a laboratory evaluation with a clinical diagnosis of a presacral mass. An abdominal ultrasound was followed by laboratory evaluation of routine hematological and hepato-renal parameters, abdomino-pelvic CT and a CT-guided biopsy.

The imaging studies showed a presacral solid mass with nodular calcifications. There was conspicuous absence of cystic or adipose contents and of sacral erosion/destruction. However, hepatic metastasis was present. All imaging features suggested a retroperitoneal sarcoma in the pelvic region with metastases to the liver. The diagnosis was confirmed by CT-guided biopsy.

Conclusions

We are reporting a new case of a very rare entity, a presacral fibrosarcoma. The imaging approach and the analysis leading to an appropriate differential diagnosis and final diagnosis is highlighted in our case report.

Transperineal aggressive angiomyxoma

A 45-year-old woman with a history of total hysterectomy with adnexal preservation for uterine leiomyomas presented to our hospital with a right gluteal palpable mass, which she first noticed 6 months before and had progressively enlarged since then.Radiological studies revealed a 14 cm lesion with translevator growth that displaced rather than invaded adjacent structures, with a peculiar whorled pattern on T2-weighted MRI, which enhanced following gadolinium administration. CT-guided biopsy was performed, and in conjunction with imaging features the diagnosis of an aggressive angiomyxoma was assumed and confirmed following surgical excision.

Fat-containing Retroperitoneal Lesions: Imaging Characteristics, Localization, and Differential Diagnosis

The complex anatomy of the retroperitoneum is reflected in the spectrum of neoplastic and nonneoplastic conditions that can occur in the retroperitoneum and appear as soft-tissue masses. The presence of fat within a retroperitoneal lesion is helpful in refining the differential diagnosis. Fat is easily recognized because of its characteristic imaging appearance. It typically is hyperechoic at ultrasonography and demonstrates low attenuation at computed tomography (-10 to -100 HU). Magnetic resonance imaging is a more ideal imaging modality because it has better soft-tissue image contrast and higher sensitivity for depicting (a) microscopic fat by using chemical shift imaging and (b) macroscopic fat by using fat-suppression techniques. Whether a lesion arises from a retroperitoneal organ or from the soft tissues of the retroperitoneal space (primary lesion) is determined by examining the relationship between the lesion and its surrounding structures. Multiple imaging signs help to determine the organ of origin, including the "beak sign," the "embedded organ sign," the "phantom (invisible) organ sign," and the "prominent feeding artery sign." Adrenal adenoma is the most common adrenal mass that contains microscopic fat, while myelolipoma is the most common adrenal mass that contains macroscopic fat. Other adrenal masses, such as pheochromocytoma and adrenocortical carcinoma, rarely contain fat. Renal angiomyolipoma is the most common fat-containing renal mass. Other fat-containing renal lesions, such as lipoma and liposarcoma, are rare. Fatty replacement of the pancreas and pancreatic lipomas are relatively common, whereas pancreatic teratomas are rare. Of the primary retroperitoneal fat-containing lesions, lipoma and liposarcoma are common, while other lesions are relatively rare. (©)RSNA, 2016.

Leiomyoma in the Retzius space

Parauterine location of leiomyomas is observed to be an extremely rare clinical condition. However, when benign or malignant primary tumours are detected in that area, they are often found in the Retzius space. There have been only six cases of leiomyomas in the Retzius space reported in the literature so far. The paper presents one such leiomyoma case located in the Retzius space. This extremely rare location of the tumour justifies its presentation. The medical records of the patient treated in the outpatient’s obstetrics and gynaecology (ob-gyn) clinic, her case history, and hospital records, supplemented by information obtained from the patient’s daughter, were analysed. The patient, a 50-year-old woman with type 2 diabetes, was referred to hospital for diagnosed secondary anaemia due to heavy menstruation for four months, which was associated with intramural leiomyoma in the anterior wall of the uterine body. Clinical examination found a large leiomyoma located in the anterior wall of the uterus. Laparotomy was performed: apart from and a leiomyoma in the uterine body it found a tumour, 140 × 100 mm in size, in the Retzius space. Total resection of the tumour was performed. Since the leiomyoma was located in the uterine wall, hysterectomy with bilateral excision of adnexa was also performed. The patient was discharged home in generally good condition on the sixth day following the operation. Concomitant occurrence of leiomyoma atypically located in the Retzius space and leiomyoma in the uterine body made perioperative diagnosis very difficult.

Hamartomas from head to toe: an imaging overview

Hamartomas are tumours composed of mesenchymal tissues such as cartilage, fat, connective tissue and smooth muscle and can be found in virtually any organ system. These masses commonly develop sporadically, but are also seen in certain syndromes such as tuberous sclerosis or Carney triad. While their imaging appearance varies depending on the organ they arise from, findings are usually unique and a diagnosis can be confidently made. Radiologists must be aware of the clinical and imaging presentations of these lesions with the particular goal of avoiding unnecessary studies or invasive procedures. Furthermore, knowledge of common syndromic entities is crucial, as the radiologist may be the first to suggest the diagnosis.

Magnetic Resonance Imaging of Pelvic Masses: A Compartmental Approach

Magnetic resonance imaging (MRI) is often "one stop shop" for evaluating female pelvic masses that helps in diagnosis, staging, and restaging of these tumors. A pelvic mass can arise from any tissue present within the pelvis. Although most masses in the female pelvis arise from the reproductive organs, masses may also arise from the gastrointestinal tract, urinary system, adjacent soft tissues, peritoneum, etc. It may not always be possible to determine the site of origin or distinguish these masses based on imaging characteristics. However, familiarity with the clinicopathologic and MRI features of most common pelvic masses helps in narrowing the differential diagnosis. Diagnosis of these masses needs a holistic approach as required for any tumor including clinical history, laboratory data, and imaging characteristics. We focus on MRI characteristics of commonly encountered pelvic masses. A compartmental imaging approach is discussed in this article that helps in identifying and characterizing these masses.

Initial Experience: Alleviation of Pain with Percutaneous CT-Guided Cryoablation for Recurrent Retroperitoneal Soft-Tissue Sarcoma

PURPOSE

To evaluate the pain-alleviating effect of computed tomography (CT)-guided percutaneous cryoablation for recurrent retroperitoneal soft-tissue sarcomas (RPSs).

MATERIALS AND METHODS

Data from 19 men and 20 women (median age, 50.3 y) with recurrent malignant RPS who underwent percutaneous cryoablation were reviewed retrospectively. A total of 50 tumors were treated by cryoablation, including a single tumor in 29 patients, 2 tumors in 9, and 3 tumors in 1. Adverse events and analgesic outcomes were compared as a function of tumor size (< 10 cm and ≥ 10 cm). Efficacy was assessed based on modified Response Evaluation Criteria In Solid Tumors and progression-free survival (PFS).

RESULTS

Grade 1/2 adverse events included fever (n = 17), emesis (n = 7), frostbite (n = 5), and local pain (n = 4). The median follow-up period and PFS were 18.5 months (range, 12-42 mo) and 13.4 months ± 6.2, respectively. At the end of follow-up, 13 patients had died and 26 were living. The mean severe local pain scores on pretreatment day 1 and posttreatment days 1, 5, 10, 15, 20, and 25 were 7.49, 7.40, 6.51, 5.81, 5.35, 5.04, and 5.44, respectively, and significant differences versus pretreatment (P < .001) were reported for posttreatment days 5-25. Immediate relief occurred more frequently in the small-tumor group (4 of 7; 57.1%; P = .018), whereas delayed relief occurred more frequently in the large-tumor group (17 of 22; 77.3%; P = .030).

CONCLUSIONS

Minimally invasive percutaneous cryoablation improves local pain and is a feasible treatment for recurrent RPSs.

Pelvic retroperitoneal pleomorphic hyalinizing angiectatic tumor (PHAT) of soft tissue: a case report

Background

Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare soft tissue tumor of low malignant potential, which most often arises in the lower extremities. Lesions occurred in other anatomic locations have been rarely reported. Moreover, their imaging features have not been well discussed. Here we report a case of PHAT arising primarily in the pelvic retroperitoneum. To our knowledge, this is the first radiological description for retroperitoneum PHAT.

Case presentation

A 26-year-old female was referred to our hospital for evaluation of a pelvic mass incidentally noted in routine pre-pregnancy ultrasonography examination. Magnetic resonance imaging (MRI) and computed tomography (CT) scan revealed an irregular mass with clear boundary in the pelvic retroperitoneum. Its signal intensity or density was inhomogeneous. On MRI images, it mainly showed isointense and slight hypointense on T1 weighted image and isointense and hyperintense on T2 weighted image. On contrast-enhanced images, it showed marked but heterogenous enhancement. With the delay time increasing, the enhanced area in the lesion increased but the CT value decreased. Dilated vessels and hemorrhage were detected in the tumor. With patience and careful separation, it was completely excised with great amount of bleeding during operation. Pathological and immunohistochemistry analysis confirmed the diagnosis of PHAT of the soft parts. We found no evidence of recurrence 18 months after operation.

Conclusion

We present an extremely rare case of PHAT arising primarily in the pelvic retroperitoneum. To our knowledge, this is the first radiological description for retroperitoneum PHAT. The provided information is useful for summarizing the characteristics of this kind of tumor. It should be included in the differential diagnosis of a well-defined, inhomogenously enhanced hypervascular soft-tissue mass in pelvic cavity.

Giant seminal vesicle cyst: an unusual site for a malignant extragastrointestinal stromal tumour

Mesenchymal tumours with clinicopathological and molecular profiles similar to gastrointestinal stromal tumours (GISTs) are, on occasion, found in extragastrointestinal locations. Extra GIST (EGIST) is a singular occurrence in the genitourinary tract. A 30-year-old man, catheterised following urinary retention, was found to have a complex pelvic retrovesical cyst on imaging. At operation, origin from the right seminal vesicle was evident with histopathology confirming a GIST. The patient received adjuvant therapy with tyrosine kinase inhibitor and is currently disease free at 2 years. This is only the second report of an EGIST at this anatomic locale. The current literature presents significant uncertainty in defining the true origin of EGISTs, particularly those in the pelvis. We propose the designation origin indeterminate stromal tumour (OIST), to facilitate disambiguation and advance accurate profiling of EGIST; a subject in evolution.

Benign and malignant tumors of the rectum and perirectal region

Although most rectal masses are histologically characterized as adenocarcinomas, the rectum and perirectal region can be affected by a wide variety of tumors and tumor-like conditions that can mimic the symptoms caused by rectal adenocarcinoma, including mucosal or submucosal rectal tumors such as lymphoma, gastrointestinal stromal tumor, leiomyosarcoma, neuroendocrine tumor, hemangioma, and melanoma, as well as tumors of the perirectal region such as developmental cyst, neurogenic tumor, osseous tumor, and other miscellaneous conditions. As a group, tumors of the rectum are considerably different from the group of tumors that arise in the perirectal region: they are most often neoplastic, symptomatic, and malignant, whereas tumors arising in the perirectal region are most commonly congenital, asymptomatic, and benign. Proctoscopy with biopsy is the most important method for the diagnosis of rectal tumors, but this procedure cannot determine the precise intramural extension of a rectal tumor and cannot accurately distinguish submucosal and intramural tumors from extramural tumors. Cross-sectional imaging, especially transrectal ultrasound and magnetic resonance imaging, allows evaluation of the entire bowel wall thickness and the perirectal tissues, helping further characterize these tumors. Recognition of the existence of these masses and their key clinical and imaging features is crucial for clinicians to accurately diagnose and appropriately manage these conditions.

Magnetic resonance imaging evaluation of non ovarian adnexal lesions

Differentiation of nonovarian from ovarian lesions is a diagnostic challenge. MRI (Magnetic Resonance Imaging) of the pelvis provides excellent tissue characterization and high contrast resolution, allowing for detailed evaluation of adnexal lesions. Salient MRI characteristics of predominantly cystic lesions and predominantly solid adnexal lesions are presented along with epidemiology and clinical presentation. Due to its excellent soft tissue resolution, MRI may be able to characterize indeterminate adnexal masses and aid the radiologist to arrive at the correct diagnosis, thus positively affect patient management.

Ossifying metaplasia of urothelial metastases: original case with review of the literature

Background

Ossifying metaplasia is an unusual feature of urothelial carcinoma, with only a few cases reported. The largest series included 17 cases and was published in 1991. The mechanism of ossification is unknown and hypotheses of osteogenic precursor cells, inducing bone formation, are proposed.

Case presentation

A 75 year-old patient was treated for a high grade transitional cell carcinoma of the bladder by surgery, chemotherapy and radiotherapy. Histology showed foci of bone metaplasia, both at the periphery of the tumor, and in a lymph node metastasis. 1 year later, a heterotopic bone formation was discovered in the right retroperitoneal space, near the lumbar spine, increasing rapidly in size during follow-up. Several imaging exams were performed (2 CT, 1 MRI, 1 Pet-CT), but in the absence of typical features of sarcoma, diagnosis remained unclear.

Histology of a CT-guided percutaneous biopsy showed urothelial carcinoma and mature lamellar bone. Integration of these findings with the radiological description of extraosseous localization was consistent with a diagnosis of osseous metaplasia of an urothelial carcinoma metastasis. The absence of bone atypia in both the primary and metastases argues against sarcomatoid urothelial carcinoma with osteosarcomatous differentiation.

Conclusion

Osseous metaplasia of an urothelial carcinoma metastasis is unusual, and difficult to distinguish from radiotherapy induced sarcoma, or from sarcomatoid carcinoma. Rapid progression, sheathing of adjacent structures such as vessels (like inferior vena cava in our case) and nerves and bony feature of lymph node metastases necessitate histological confirmation and rapid treatment. Our case illustrates this disease and evaluates the imaging features. In addition we discuss the differential diagnosis of osseous retroperitoneal masses.

Report of a case: Retroperitoneal mucinous cystadenocarcinoma with rapid progression

INTRODUCTION

Retroperitoneal mucinous cystic neoplasms are uncommon, and little is known about the etiology of the disease. Malignant forms of these are extremely rare. Here, we report a case of primary retroperitoneal mucinous cystadenocarcinoma (PRMC), which demonstrated unexpectedly aggressive progression despite finding only a limited area of adenocarcinoma.

PRESENTATION OF CASE

A 62-year-old woman with a complaint of abdominal discomfort was admitted to the hospital. Abdominal CT and MRI showed multiple large retroperitoneal cysts dislocating the right kidney nearly to the center of the abdomen. Transabdominal resection of the cysts was performed. Those cysts contained 1100ml of mucinous fluids in total. Cytological examination of those fluids revealed no malignant cells. The cyst wall was lined with mucinous epithelial cells, and contained some ovarian-type stroma. Also, there was a focal area of adenocarcinoma in the cyst wall, and the lesion was diagnosed as primary retroperitoneal mucinous cystadenocarcinoma. Eight months later, the patient developed lumbar bone metastasis. Chemotherapy with S-1, an oral fluoropyrimidine, and docetaxel had been begun immediately; however, the disease had rapidly spread in the retroperitoneum. Eventually, the patient died of the disease 15 months after surgery.

DISCUSSION

Retroperitoneal mucinous cystic neoplasms are considered to be metaplasia of embryonal coelomic epithelium. Complete excision without rupture is essential. However, variance of biological aggressiveness might exist in PRMCs.

CONCLUSION

Retroperitoneal mucinous cystadenocarcinoma is a rare tumor, and it is urgently necessary to elucidate the etiology of an effective therapy for the disease.

Dedifferentiated liposarcoma involving the spleen and splenic hilum: a report of a case with a rare growth pattern

We present a rare case of dedifferentiated liposarcoma confined to the spleen and splenic hilum. An 81-year-old man was referred to our hospital with a large asymptomatic splenic tumor. The patient underwent splenectomy, and the adipose tissue surrounding the splenic hilum was also resected. Microscopically, the tumor mainly consisted of high-grade spindle cells similar to those seen in undifferentiated pleomorphic liposarcoma. In the splenic hilum, scattered atypical cells were detected in the sclerosing component and adipose tissue. Immunohistochemically, both the spindle cells in the spleen and the atypical cells in the splenic hilum were positive for MDM2 and CDK4. The histopathologic diagnosis was dedifferentiated liposarcoma derived from an atypical lipomatous tumor/well-differentiated liposarcoma of the adipose tissue in the splenic hilum with extension into the spleen. Dedifferentiated liposarcoma in the spleen and splenic hilum should be considered as a differential diagnosis of splenic tumors.

Ischemic colitis due to a mesenteric arteriovenous malformation in a patient with a connective tissue disorder

Ischemic colitis is a rare, life-threatening, consequence of mesenteric arteriovenous malformations. Ischemia ensues from a steal phenomenon through shunting, and may be compounded by the resulting portal hypertension. Computed tomographic angiography is the most common first-line test because it is quick, non-invasive, and allows for accurate anatomic characterization. Also, high-resolution three-dimensional images can be created for treatment planning. Magnetic resonance angiography is similarly sensitive for vascular mapping. Conventional angiography remains the gold standard for diagnosis and also allows for therapeutic endovascular embolization. Our patient underwent testing using all three of these modalities. We present the first reported case of this entity in a patient with a vascular connective tissue disorder.

Retroperitoneal tumors in the pelvis: a diagnostic challenge in gynecology

Retroperitoneal tumors can pose a diagnostic and therapeutic challenge to gynecologists because of their rarity, late presentation, and complex anatomical location in the retroperitoneum. This article reviews the diagnosis and management of retroperitoneal tumors in the pelvis, and highlights the potential pitfalls that may be faced by gynecologists.

Presacral myelolipoma. A case report and literature review

Many reports have described adrenal myelolipomas but there have been only a few reports of extra-adrenal myelolipomas. We describe a 74-year-old woman who came to our observation for MRI of the lumbar spine for typical lumbar back pain. In addition to signs of mild scoliosis and spondylo disc arthrosis, MR imaging revealed a presacral mass showing a heterogeneously high signal in all pulse sequences and almost completely suppressed on inversion recovery sequences for fat tissue. CT imaging confirmed the fatty nature of the lesion and no signs of bone involvement. These findings were most consistent with a diagnosis of a rare presacral myelolipoma as confirmed at histopathologic analysis. This work reports a case of one of the rarest presacral masses, emphasizing the role of imaging in the differential diagnosis of other presacral masses.

[Presacral giant solitary neurofibroma: a rare cause of pelvic mass in women]

Le neurofibrome présacré solitaire est une tumeur ectodermiquetrès rare tant par sa fréquence que par sa localisation, souvent pauci-symptomatiquejusqu’à l'atteinte de taille importante, d'accès difficile et de diagnostic erroné. L'imagerie préopératoirejoue un rôle essentieldans la prise en charge. Son diagnostic est immuno-histologique. Son traitement chirurgical est basé sur l'exérèse complète à marges saines. Nous rapportons l'observation d'une patiente de 46 ans, ayant été opérée pour suspicion de fibrome utérin sous séreux, dont l'exploration chirurgicale a confirméune tumeur rétropéritonéale et présacrée. L'IRM post opératoire a précisé ses rapports anatomiques. La reprise chirurgicalea permis l'exérèse complète de la tumeur sans lésions des organes adjacents. L'histologie et l’étude immuno-histochimique ont conclu à un neurofibrome.

Role of 18F-DOPA PET/CT in diagnosis and follow-up of adrenal and extra-adrenal paragangliomas

PURPOSE

The objective of this study was to establish the clinical value of F-DOPA PET/CT in patients with adrenal and extra-adrenal paragangliomas (PGLs).

METHODS

Twenty-six consecutive patients with suspected or recurrent PGL underwent MR (and/or CT) and F-DOPA PET/CT. Histopathology confirmation was obtained in 20 cases. Genetic analysis on known susceptibility genes for PGL (VHL, RET, SDHx, TMEM127) was available in 13 patients.

RESULTS

Fourteen patients were affected by PGL (8 with head/neck location, 6 with abdominal/thoracic location), whereas 12 showed masses of other origin. Three patients proved to be SDHD, 1 SDHB, 2 SDHC, and 1 TMEM127 mutation carriers. F-DOPA PET/CT showed pathological uptake in 13 of 26 patients. The procedure identified all PGLs except one with bone metastases (previous malignant adrenal PGL). No uptake was found in patients without proven PGL. Thus, in the whole group, F-DOPA PET/CT sensitivity was 92.8%, and specificity was 100% with positive and negative predictive values of 100% and 92.3%, respectively. Total diagnostic accuracy was 96.2%. In the head/neck subgroup, sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were 100%. In the abdominal location, sensitivity was 80% and specificity was 100%, and positive and negative predictive values were 100% and 91.7%, respectively. Abdominal diagnostic accuracy was 93.7%. Radiotracer uptake was superimposable in head/neck PGLs versus abdominal PGLs and in mutated versus wild-type patients.

CONCLUSIONS

The high diagnostic performance of F-DOPA PET/CT showed this technique to be a useful tool in detecting PGLs, above all those located at the head/neck site, regardless of the genetic pattern.

Radiographic diagnosis and differentiation of an aggressive angiomyxoma in a male patient

Aggressive angiomyxoma is a rare soft-tissue tumor which usually occurs in female patients of reproductive age. Its occurrence in men is even more unusual and as illustrated in this case the difference between pathology suggested by a physical examination and its actual extent can be quite striking. We present a case report of an 81-year-old man with the typical MRI appearances of a pelvic aggressive angiomyxoma, describe imaging and histopathologic features of this rarely seen locally infiltrative neoplasm and also discuss therapeutic options for patients with an aggressive angiomyxoma.