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

largest reported ipoma in the United States of America

A woman in her early 60s presented for evaluation of an asymptomatic left groin mass. CT imaging noted a large fatty tumour replacing the majority of the abdominal and pelvic cavities. The patient underwent uneventful resection of a 53×36×9 cm mass of the retroperitoneal (RP) space. The pathology report was compatible with a lipoma. This is the largest noted RP lipoma in the US literature. In this case report, we also offer a literature review of the diagnosis and management of fat-containing retroperitoneal masses.

Total retroperitoneal lipectomy improves prognosis in patients with primary retroperitoneal liposarcoma: a comparative study

Background

Retroperitoneal liposarcoma (RPLS) is the most common soft tissue sarcoma originating in the retroperitoneal space. Although surgery is the standard treatment, recurrence remains frequent. In this study, we aimed to explore the safety and efficacy of total (ipsilateral) retroperitoneal lipectomy (TRL) compared to traditional complete resection (CR) for primary RPLS.

Methods

We retrospectively analyzed patients with primary RPLS treated at our center between January 2014 and December 2020. Univariate and multivariable Cox regression analyses assessed the impact of demographic, operative, and clinicopathological variables on recurrence-free survival (RFS) and overall survival (OS). Kaplan-Meier plots illustrated RFS and OS, and the log-rank test compared time-to-event distributions.

Results

A total of 81 patients were included in the final analysis: 37 in the CR group and 44 in the TRL group. Demographic and clinicopathologic parameters were comparable between the two groups. Post-operative morbidity occurred in 30.9% of cases, with 15 (40.5%) in the CR group and 10 (22.7%) in the TRL group (P=0.086). There were 9 cases of severe complications at grade 3 or higher, with 5 cases in the CR group and 4 cases in the TRL group. There was no significant difference between the two groups (P=0.314). The TRL group demonstrated improved RFS and OS, particularly among dedifferentiated liposarcoma (DDLS) patients.

Conclusions

Total retroperitoneal lipectomy (TRL) appears to be a safe procedure that enhances survival outcomes in patients with primary RPLS. Further studies are needed to validate these findings.

Perinephric myxoid pseudotumor of fat: A series of 13 cases and literature review

Perinephric myxoid pseudotumor of fat (PMPF) is a recently described and rare retroperitoneal mass-forming lesion whose clinical significance chiefly involves mimicry of a variety of soft tissue tumors. For unknown reasons, it commonly occurs in male patients with underlying non-neoplastic renal diseases and/or type 2 diabetes (DMT2). A total of 55 cases have been reported in the literature. Recently, we have encountered 13 such masses with peculiar histologic features; thus, we sought to investigate our experience and review the clinicopathologic characteristics of the literature. Our series confirms that PMPF frequently occurs in adult male patients (11/13, 85%), with an average age of 66 years, and commonly co-occurs with renal disease, such as DMT2 (2/13, 15%), end-stage renal disease (ESRD) (5/13, 39%), renal cysts (4/13, 31%), concurrent or prior renal neoplasia (2/13; 15%), and myeloma/lymphoma (2/13; 15%). Histologic evaluation shows lipomatous masses commonly showing variable amounts of fat necrosis, myxoid degeneration, lymphoplasmacytic inflammation and lacking atypical hyperchromatic stromal spindle cells. Unusual histologic features include extramedullary hematopoiesis (1/13, 8%), hemosiderin deposition (4/13, 31%), and small wisps of mature smooth muscle (6/13, 46%). All cases tested were negative for MDM2 and did not show an increased ratio of IgG4+/IgG+ plasma cells. Our study confirms the clinical and pathologic features of PMPF and expands its histologic spectrum, underscoring the importance of this entity as a benign pseudotumor which should be included in the differential diagnosis of other fat-containing retroperitoneal masses, particularly well-differentiated liposarcoma.

A 50-year-old patient with pancreatitis revealing pancreatitis, panniculitis, and polyarthritis syndrome-a case report and review of the literature

The combination of pancreatitis, panniculitis, and polyarthritis (PPP) is a rare systemic syndrome that occurs in patients with acute or chronic pancreatitis or pancreatic malignancies. A 50-year-old male patient presented with polyarthritis increasing for 1 week and consequent inability to walk unaided. In addition, the patient had several isolated nodules on the lower extremities without any tenderness to pressure. Laboratory tests showed elevated pancreatic enzymes indicative of pancreatitis, which was thereafter confirmed by abdominal CT scan, with signs of chronic pancreatitis and concrements in the pancreatic duct. The diagnosis of panniculitis was established by dermatological consultation. Considering all these clinical features, PPP syndrome was diagnosed. In accordance with the pre-existing literature, oral glucocorticoid therapy and nonsteroidal anti-inflammatory drugs (NSAIDs) were given but failed to improve pain and polyarthritis. In the further clinical course, due to the persistent increase in lipase and amylase, endoscopic retrograde cholangiopancreatography (ERCP) was performed, showing small concrements in the pancreatic duct. During the intervention, the pancreatic duct was widened, the small concrements were removed, and a pancreatic duct stent was then implanted. Following ERCP, an instant decrease in pancreatic enzymes was observed, accompanied by a clear and sustained improvement of joint swellings and pain. With the typical triad of clinical findings in mind, one should consider PPP syndrome in the context of acute or chronic pancreatitis as well as in pancreatic malignancies. All involved disciplines (gastroenterology, dermatology, and rheumatology) should be familiar with this rare but severe condition. The prognosis depends on the extent of the functional deficit of the extremities and the progression of the underlying disease.

Advancements in Diagnosis and Multimodal Treatment Strategies for Retroperitoneal Tumors: A Comprehensive Review

Retroperitoneal tumors (RPTs) encompass both benign and malignant entities, constituting ~0.1% to 0.2% of all malignant tumors, of which 70% to 80% manifest malignancy. Predominantly, retroperitoneal sarcomas (RPS) represent the most prevalent subtype among RPT. With over 70 histologic forms identified, liposarcomas and leiomyosarcomas emerge as the primary constituents of RPS. Accurate diagnosis of RPTs necessitates preoperative core-needle biopsy and comprehensive imaging assessment. The current staging protocol for RPS relies on the eighth edition of the American Joint Committee on Cancer/TNM classification. Surgical excision remains the established gold standard for treating RPS. Therapeutic approaches vary according to the underlying pathophysiology. Although chemotherapy and radiotherapy exhibit efficacy in managing metastatic and recurrent unresectable RPS, their role in primary RPS remains unresolved, necessitating further clinical trials for validation. Concurrently, ongoing research explores the potential of targeted therapies and immunotherapy. This literature review aims to provide a comprehensive overview of existing research, delineating diagnostic pathways and optimal therapeutic strategies for RPT.

Pancreas-sparing tumor resection for peripancreatic paraganglioma: a case series of six patients

Paragangliomas (PGLs) located around the pancreas are rare and challenging to diagnose preoperatively. Tumor resection with pancreatectomy is often performed for peripancreatic PGL. However, pancreas-sparing tumor resection can be indicated with an accurate preoperative diagnosis. Six patients with pathologically diagnosed peripancreatic PGL were included. The clinical data were retrospectively collected from medical records. Five of them were suspected of peripancreatic PGL on imaging studies due to the fat plane identified between the tumor and pancreas, and subsequently diagnosed with PGL preoperatively based on elevated urinary catecholamine levels and/or metaiodobenzylguanidine scintigraphy without biopsy. All patients underwent pancreas-sparing tumor resection with negative surgical margins, and they did not develop postoperative complications related to potential damage to the pancreas. A fat plane between the tumor and pancreas on imaging studies and hormone levels are key findings for obtaining an accurate preoperative diagnosis of peripancreatic PGL, which can be managed with pancreas-sparing tumor resection.

Clinical Characteristics of Adrenal Hemangioma

Objective

Adrenal hemangioma (AH) is a rare, benign adrenal tumor often detected incidentally by imaging. This retrospective study aimed to investigate the clinical characteristics of AH, including clinical and diagnostic imaging features, to improve the recognition and understanding of AH.

Methods

We retrospectively analyzed the medical records of patients diagnosed with AH at Peking Union Medical College Hospital between 2008 and 2022. Clinical manifestations, adrenal hormone levels, imaging findings, treatment approaches, and pathological results were collected and analyzed.

Results

Of the 7140 adrenal tumor patients, 40 (0.56%) had AH confirmed postoperatively. The mean age at diagnosis was 53.9 years, with a female predominance. Most (70%) were asymptomatic and diagnosed incidentally. Misdiagnosis before surgery was common, most frequently as pheochromocytoma. Imaging characteristics, especially enhanced computed tomography, revealed distinct features based on tumor size. Surgery was the main treatment, with laparoscopic adrenalectomy preferred.

Conclusion

This study elucidates the clinical characteristics of AH, including demographics, diagnostic challenges, and imaging features. AH often presents incidentally and is frequently misdiagnosed preoperatively. Recognizing distinct imaging characteristics and appropriate surgical management can enable accurate diagnosis and optimal treatment.

Soft-Tissue Sarcomas of the Genitourinary Tract with Radiologic-Pathologic Correlation

Genitourinary tract soft-tissue sarcomas are rare neoplasms with varied pathologic and clinical features. While some of these tumors may be aggressive high-grade malignancies, others are low grade with a relatively better prognosis. Given that the grade and extent of the disease are important prognostic factors in these tumors, timely diagnosis is crucial. Unfortunately, most imaging features of these malignancies are not pathognomonic, and various histologic subtypes do not manifest with typical classic imaging features. Therefore, reliable differentiation of the various histologic tumor types is not always possible based solely on the radiologic manifestations. Imaging findings need to be considered in the context of clinical history in corroboration with radiologic-pathologic correlation. The authors discuss the specific imaging and pathologic characteristics of various genitourinary tract soft-tissue sarcomas, emphasizing diagnostic difficulties and differential diagnoses. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Analysis of recurrence and metastasis patterns and prognosis after complete resection of retroperitoneal liposarcoma

Objective

To analyze the recurrence and metastasis patterns and prognosis after complete resection of retroperitoneal liposarcoma.

Methods

The clinical postoperative follow-up data and results of patients who underwent complete resection of retroperitoneal liposarcoma from September 10, 2014, to September 8, 2021, at Hebei Medical University hospital were collected retrospectively.

Results

A total of 60 patients with complete resection of retroperitoneal liposarcoma, including 33 cases of retroperitoneal liposarcoma recurrence, 2 cases of liver metastasis, and 1 case of lung metastasis, were included. The results showed that 100% of the recurrent sites were located in the primary region of the tumor, with most recurrences located near the kidney, paracolic sulci, and iliac vessels. Three patients had distant metastasis without obvious recurrence on imaging examination. The pathological type of retroperitoneal liposarcoma, Ki67 expression, and presence of serum albumin were risk factors for recurrence and metastasis after complete resection of retroperitoneal liposarcoma. The malignancy and Ki67 expression were independent risk factors for recurrence and metastasis as well as for overall survival of patients undergoing complete resection of retroperitoneal liposarcoma.

Conclusion

Complete resection remains the most effective method to treat retroperitoneal liposarcoma. Patients with pathological types of retroperitoneal liposarcoma showing dedifferentiation, pleomorphism, mixed type, and high Ki67 expression should be closely monitored and observed after complete resection, especially for imaging changes in the primary tumor area.

Imaging Findings and Misdiagnosis of Bronchogenic Cysts: A Study of 83 Cases

Objective

We characterize computed tomography (CT) and magnetic resonance imaging (MRI) features of bronchogenic cysts (BCs) and analyze misdiagnosis.

Methods

The retrospective study consisted of 83 patients with BCs. CT and MRI images were assessed for mass location, maximum diameter, density, calcification, signal intensity, and enhancement pattern. Eighty-three patients underwent plain CT in which 53 underwent enhanced CT. Thirteen patients received both plain and enhanced MR, and only one received just a plain MR.

Results

Eighty-three masses were all solitary, with 71 having a roundish morphology, and twelve having a lobulated or irregular morphology. Sixty-six masses are mediastinal type, four are intrapulmonary type, and 13 are ectopic type. Calcification occurred in 14 lesions. On plain CT, 13 lesions displayed water-like attenuation (-20-20 Hu), and 70 showed soft-tissue attenuation (≥21 Hu). On T1WI, eight masses were hyperintense, three were isointense, and three were hypointense. Fourteen masses were hyperintense on T2WI and (Apparent Diffusion Coefficient) ADC sequence. On (Diffusion Weighted Imaging) DWI, six masses were hypointense and eight were hyperintense. Enhanced T1WI showed seven cases were unenhanced, while six were marginally enhanced. Twenty cases were misdiagnosed as thymomas, eleven as neurogenic tumors, six as lymphangiomas, and two as lung cancer. Five cases were misdiagnosed as other diseases. Patients with BCs underwent MR (42.9%) had a lower rate of misdiagnosis than those who underwent CT alone (53.0%).

Conclusion

The imaging findings of BCs in the chest are generally consistent. Misdiagnosis occurs frequently when CT attenuation values exceed 20 Hu. Diagnostic accuracy of BCs tends to improve with preoperative MR examination.

Giant retroperitoneal well differentiated liposarcoma: A case report and literature review

INTRODUCTION AND IMPORTANCE

The most prevalent type of primary retroperitoneal tumors is soft tissue sarcoma (STS). Liposarcoma accounts for 40 % of retroperitoneal tumors (Mack, 1995). Retroperitoneal liposarcoma accounts for 12 % to 40 % of all liposarcomas (Vijay and Ram, 2015). They typically present with advanced disease and often carry a poor prognosis. Because of their rarity and anatomic location, these malignant tumors can cause a diagnostic dilemma and present several therapeutic challenges (Vijay and Ram, 2015).

CASE PRESENTATION

A 48-year-old male patient presented to our gastrointestinal oncology clinic with a 2-year history of abdominal discomfort, weight loss and steadily growing abdominal swelling. A soft, rubbery lobulated mass with a positive "slippage sign" was palpable over all the quadrants of the abdomen. CT scan conclusion was retroperitoneal lipoma with internal enhancing nodular components. During laparotomy, a fatty mass measuring 55*60*22 cm and weighing 14 kg was excised. Histopathologic report showed a well differentiated liposarcoma (WDLS).

CLINICAL DISCUSSION

Giant retroperitoneal liposarcoma (RPL) is exceedingly rare. Liposarcomas have diverse MRI and CT appearances due to the various subtypes. WDLS are difficult to identify from lipomas before surgery. Histopathology is the only way to provide a reliable diagnosis; therefore en block resection is the recommended approach when malignancy cannot be ruled out.

CONCLUSION

Although imaging with ultrasound, CT, and MRI can aid in the diagnosis, differentiating WDLS from lipoma pre-operatively can be difficult, and en block resection is the recommended approach when malignancy cannot be ruled out.

A Large Retroperitoneal Liposarcoma Mimicking an Angiomyolipoma on Pre-operative Imaging: A Case Report

Retroperitoneal masses present a diagnostic challenge due to their elusive origin and varied clinical manifestations. Among these masses, retroperitoneal liposarcomas, rare tumors of mesenchymal origin, often grow asymptomatically until compressing surrounding structures, necessitating accurate and early diagnosis. Renal angiomyolipomas (AMLs) have also been reported to mimic retroperitoneal liposarcomas on radiographic imaging, further complicating diagnostic processes. The presented case report describes a rare instance of a large well-differentiated liposarcoma that mimicked a renal angiomyolipoma on imaging in a 58-year-old male patient. The patient initially presented with worsening abdominal distension, early satiety, and left-sided flank pain for the past year. Radiographic imaging revealed a large mixed echogenic lesion measuring 22 x 13 cm in the left kidney with diffuse fat contribution, suspected to be a giant renal angiomyolipoma. The patient underwent selective arterial embolization by interventional radiology. Follow-up imaging eight months later showed an increase in the size of the mass, raising suspicion of a liposarcoma. Surgical resection of the mass and a radical left nephrectomy were performed, with final pathology confirming the diagnosis of a well-differentiated liposarcoma. This case highlights the importance of accurate diagnosis and the potential for liposarcomas to mimic other masses on imaging, despite their rarity.

Simultaneous adrenal and retroperitoneal myelolipoma resected by laparoscopic surgery: a challenging case

BACKGROUND

Myelolipoma is a benign neoplasm of the adrenal cortex, composed of fat and hematopoietic cells. Although myelolipoma is benign, differentiation from adrenocortical cancer may be difficult. The presence of adrenal and extra-adrenal myelolipomas simultaneously is sporadic, making it a challenging case, especially when the preoperative diagnosis is ambiguous.

CASE PRESENTATION

A 65-year-old man was referred to our clinic due to a mass in the adrenal fossa. In the abdominopelvic computed tomography (CT), a well-circumscribed fat-containing 78 × 61 × 65 mm bi-lobulated mass was reported in the left adrenal fossa. The first differential diagnosis was myelolipoma. The patient was then referred to our clinic for a mass excision. He was asymptomatic and was scheduled to undergo laparoscopic-assisted adrenalectomy. After adrenalectomy and mass dissection, surprisingly, another mass was detected in the retroperitoneal area. The second mass was also dissected. The final diagnosis was myelolipoma for both masses. The patient has been symptom-free for nine months after the operation.

CONCLUSION

Simultaneous adrenal and extra-adrenal myelolipoma should be considered as one of the differential diagnoses. However, because this situation is extremely rare, the probability of malignancy should be highly regarded, and we suggest an obsessive approach when approaching this condition. It is essential to manage these cases on a case-by-case basis and tailor the management concerning intraoperative biopsy, the intraoperative appearance of tumors, and the location of extra-adrenal masses.

Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards

The radiologic diagnosis of adrenal disease can be challenging in settings of atypical presentations, mimics of benign and malignant adrenal masses, and rare adrenal anomalies. Misdiagnosis may lead to suboptimal management and adverse outcomes. Adrenal adenoma is the most common benign adrenal tumor that arises from the cortex, whereas adrenocortical carcinoma (ACC) is a rare malignant tumor of the cortex. Adrenal cyst and myelolipoma are other benign adrenal lesions and are characterized by their fluid and fat content, respectively. Pheochromocytoma is a rare neuroendocrine tumor of the adrenal medulla. Metastases to the adrenal glands are the most common malignant adrenal tumors. While many of these masses have classic imaging appearances, considerable overlap exists between benign and malignant lesions and can pose a diagnostic challenge. Atypical adrenal adenomas include those that are lipid poor; contain macroscopic fat, hemorrhage, and/or iron; are heterogeneous and/or large; and demonstrate growth. Heterogeneous adrenal adenomas may mimic ACC, metastasis, or pheochromocytoma, particularly when they are 4 cm or larger, whereas smaller versions of ACC, metastasis, and pheochromocytoma and those with washout greater than 60% may mimic adenoma. Because of its nonenhanced CT attenuation of less than or equal to 10 HU, a lipid-rich adrenal adenoma may be mimicked by a benign adrenal cyst, or it may be mimicked by a tumor with central cystic and/or necrotic change such as ACC, pheochromocytoma, or metastasis. Rare adrenal tumors such as hemangioma, ganglioneuroma, and oncocytoma also may mimic adrenal adenoma, ACC, metastasis, and pheochromocytoma. The authors describe cases of adrenal neoplasms that they have encountered in clinical practice and presented to adrenal multidisciplinary tumor boards. Key lessons to aid in diagnosis and further guide appropriate management are provided. © RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Imaging of Ganglioneuroma: A Literature Review and a Rare Case of Cystic Presentation in an Adolescent Girl

Retroperitoneal ganglioneuroma is a rare neuroectodermal tumor with a benign nature. We performed a literature review among 338 studies. We included 9 studies, whose patients underwent CT and/or MRI to characterize a retroperitoneal mass, which was confirmed to be a ganglioneuroma by histologic exam. The most common features of ganglioneuroma are considered to be a solid nature, oval/lobulated shape, and regular margins. The ganglioneuroma shows a progressive late enhancement on CT. On MRI it appears as a hypointense mass in T1W images and with a heterogeneous high-intensity in T2W. The MRI-"whorled sign" is described in the reviewed studies in about 80% of patients. The MRI characterization of a primitive retroperitoneal cystic mass should not exclude a cystic evolution from solid masses, and in the case of paravertebral location, the differential diagnosis algorithm should include the hypothesis of ganglioneuroma. In our case, the MRI features could have oriented towards a neurogenic nature, however, the predominantly cystic-fluid aspect and the considerable longitudinal non-invasive extension between retroperitoneal structures, misled us to a lymphatic malformation. In the literature, it is reported that the cystic presentation can be due to a degeneration of a well-known solid form while maintaining a benign character: the distinguishing malignity character is the revelation of immature cells on histological examination.

Current management of benign retroperitoneal tumors

Benign retroperitoneal tumors (BRT) represent a rare group of heterogeneous diseases. The literature lacks high-quality evidence about the optimal management of BRT, and most of the information available takes the form of case reports or case series. The aim of this review is to provide an overview of current management strategies for adult patients with BRT. A literature search using PubMed indexed articles was conducted and BRT were classified into five different biological subgroups: 1) lipomatous tumors, 2) smooth muscle tumors, 3) peripheral nerve sheath tumors, 4) myofibroblastic tumors, and 5) others. Tumors that are primarily pelvic in origin were excluded. Despite the significant heterogeneity of the disease, several generic considerations have emerged and can be applied to the management of BRT. Specifically, the risk of misdiagnosing a BRT with another pathology such as retroperitoneal sarcoma is notable. When encountered, suspected BRT should therefore be referred to a specialized sarcoma center. Multidisciplinary tumor boards, present at these centers, have a pivotal role in managing BRT. The decision of whether to offer surgery, nonsurgical treatment or a "watch-and-wait" approach should be made after multidisciplinary discussion, depending on tumor histology. Moving forward, collaborative research efforts dedicated to BRT remain crucial in gathering evidence and knowledge to further optimize patient care.

Fat Necrosis Mimicking Local Recurrence With Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) Positivity After Partial Nephrectomy for Renal Cell Carcinoma

We report a case of fat necrosis with positive results on fluorodeoxyglucose positron emission tomography (FDG-PET)-CT imaging after partial nephrectomy. A 77-year-old man underwent a partial nephrectomy for a right renal mass. The histopathological results showed clear cell renal cell carcinoma, G1>G2, pT1a. Four and a half years after surgery, a nodule appeared in the retroperitoneal space on CT. FDG-PET CT showed increased uptake in the nodule, indicating local recurrence of carcinoma. A right nephrectomy was performed. The histopathological diagnosis was fat necrosis.

CT and MR Imaging of Retroperitoneal Sarcomas: A Practical Guide for the Radiologist

Primary retroperitoneal sarcomas (RPS) represent around 10-16% of all sarcomas, with liposarcomas and leiomyosarcomas being the most common subtypes. RPS have some peculiar characteristics, imaging appearances, worse prognosis, and complications compared to other locations of sarcoma. Commonly, RPS primarily present as large masses, progressively encasing adjacent structures, causing mass effect, and complications. RPS diagnosis is often challenging, and these tumors may be overlooked; however, failure to recognize RPS characteristics leads to a worse prognosis for the patients. Surgery is the only recognized curative treatment, but the anatomical constraints of the retroperitoneum limit the ability to achieve wide resection margins; therefore, these tumors have a high rate of recurrence, and require long-term follow-up. The radiologist has an important role in the diagnosis of RPS, the definition of their extent, and their follow-up. Specific knowledge of the main imaging findings is required to reach an early diagnosis, and, ultimately, to guarantee the best patient management. This article provides an overview of the current knowledge regarding cross-sectional imaging features of patients with retroperitoneal sarcomas, presenting tips and tricks to improve imaging diagnosis of RPS.

Meta-analysis of reported presacral myelolipomas, including a report of a new case

BACKGROUND

Presacral myelolipomas form a rare disease and are often found incidentally in imaging diagnostics.

CASE PRESENTATION

In this study, we report the case of a 71-year-old caucasian female with an incidental finding of a retroperitoneal tumor on magnetic resonance imaging scan. This report aimed at presenting the clinical course of this patient with emphasis on analysis of pathological, clinical, and epidemiological features in a meta-analysis of reported cases.

CONCLUSION

Presacral myelolipomas are rare and its etiology remains unclear. Surgical resection is indicated in symptomatic lesions and lesions > 4 cm. More clinical and pathological research on this rare entity is warranted.

Localized Multifocal Retroperitoneal Ganglioneuroma with an Infiltrative Appearance on Imaging: A Case Report

Multifocal ganglioneuromas are characterized by the presence of multiple benign neuroepithelial tumor nodules and are less common than solitary tumors. A small percentage of ganglioneuromas present with a fatty appearance. Only a few cases of multifocal ganglioneuromas have been reported, due to both their rarity and minimal symptomatic presentation; therefore, generalizations about risk factors and predictive markers are very difficult. Here, we report a case of multifocal retroperitoneal ganglioneuroma with an infiltrative appearance on computed tomography (CT). The tumor demonstrated slow growth on multiple imaging studies and was associated with abdominal and flank pain. The aggressive appearance eventually led to surgical resection 18 months after the initial incidental finding on CT. Postsurgical analysis of the tumor on imaging was crucial in revealing its nodularity and infiltration, as well as for clarifying its retroperitoneal location inseparable from the adrenal gland. Histology demonstrated Schwann cells and ganglion cells without atypia or increased cellularity, and with no mitosis or necrosis seen. Our case highlights the consideration of ganglioneuroma with fatty infiltration in the differential diagnosis of a fatty tumor in the mediastinum or retroperitoneum. Additionally, our report differentiates multifocal ganglioneuroma with fatty infiltration from lipomatous ganglioneuroma on radiology and histopathology.

Retroperitoneal lipoma and bilateral renal cell carcinoma in a rare co-existence

Introduction

Giant retroperitoneal lipomas are rarely observed clinically, and a retroperitoneal lipoma accompanied by renal cell carcinoma is even more unusual. We present a case of a large retroperitoneal lipoma with bilateral renal cell carcinoma that was definitively diagnosed after resection.

Case presentation

A huge retroperitoneal mass was incidentally discovered in a 58-year-old male with end stage renal disease being evaluated for a kidney transplant. Imaging studies revealed a mixed solid and fat-containing mass displacing the left kidney. Repeat imaging discovered concurrent unilateral renal cell carcinoma and interval enlargement of the mass. Histopathology showed benign adipose tissue, bland spindle cells, and mixed inflammatory infiltrate that was negative for MDM2 amplification. Resection of the mass and bilateral nephrectomy was performed. Final histopathological examination was consistent with bilateral renal cell carcinoma and a large benign retroperitoneal lipoma.

Discussion

The presented case provides a prime example of the diagnostic challenges encountered with retroperitoneal tumors, The final diagnosis of lipoma in this case was only made after review of the resected specimen in its entirety. Retroperitoneal lipomas can present differently based on tumor size and involvement of adjacent organs. The concomitant occurrence of a renal cell carcinoma and retroperitoneal lipoma is extremely rare, and this is the first report published in the literature.

Conclusion

We document a rare case of retroperitoneal lipoma with concurrent bilateral renal cell carcinoma and illustrate frequently encountered challenges during the evaluation of retroperitoneal masses.

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This retroperitoneal lipoma with bilateral renal cell carcinoma is the first case to be reported in the medical literature.

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This case provides a prime example of the diagnostic challenges encountered with retroperitoneal tumors.

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We illustrated frequently encountered challenges during the evaluation of retroperitoneal masses.

Utility of high-resolution ultrasound in measuring subcutaneous fat thickness

OBJECTIVE

Previous studies conclude that high-resolution ultrasound (HRUS) enables noninvasive and accurate measurements of subcutaneous fat thickness. The primary objective of this cross-sectional study was to better characterize subcutaneous fat thickness measurements in a diverse patient population using HRUS. Secondarily, we sought to correlate these measurements with patients' body image.

METHODS

A cross-sectional study to measure subcutaneous fat measurements at seven distinct anatomic sites, including upper and lower extremities, submental, and torso regions, in 40 men and women of different ages and races using HRUS. Independent t-tests and analysis of variance were performed to analyze findings.

RESULTS

In our patient population, on average, women had thicker subcutaneous fat than men at all anatomic sites. Asian patients had significantly reduced fat thickness at peripheral anatomic sites, such as arms when compared to patients who identified as Black and Other (p = 0.05 and p = 0.008, respectively). Lastly, women reported decreased total body satisfaction at all anatomic sites when compared to men.

CONCLUSION

The information obtained and methods developed in this study may be utilized clinically during patient selection for fat reduction procedures, including for estimating the degree of likely benefit; for managing pathologies involving subcutaneous fat thickness alteration; and to monitor the progression of lipodystrophy secondary to disease or drugs.

Perinephric myxoid pseudotumor of fat: a multimodality imaging case series

Perinephric myxoid pseudotumor of fat (PMPF) is an unusual clinical entity with few prior imaging case reports. We report a multimodality imaging case series of PMPF, consisting of four cases seen in our department with both imaging studies and histopathologic confirmation. Three of the four patients had a history of advanced non-neoplastic renal disease. The perirenal masses in these cases varied in size and appearance. Some lesions resembled cysts or contained macroscopic fat. Enhancement was equivocal on CT, but prominent in one case on MRI and in another on contrast-enhanced ultrasound. Although not known to be malignant, PMPF may be confused for a cyst, liposarcoma, or hypovascular solid neoplasm on imaging. The dominant mass was resected in two cases because of concern for malignancy, while percutaneous CT-guided biopsy was performed in the other two. Mouse double minute 2 (MDM2) gene amplification by fluorescence in situ hybridization (FISH) was negative in all four cases, excluding well-differentiated liposarcoma. Radiologists should be familiar with PMPF to provide appropriate guidance on clinical management.

Lipoma and Its Doppelganger: The Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma

Lipomatous tumors are among the most common soft tissue lesions encountered by the general surgeon. Shared history and clinical presentation make differentiation between benign lipomas and low-grade liposarcomas a diagnostic dilemma. This article reviews the epidemiology, clinical history, diagnostic workup, management, natural history, and surveillance of benign lipomas and atypical lipomatous tumors/well-differentiated liposarcomas. Although it is important that aggressive, potentially malignant atypical lipomatous tumors and liposarcomas be managed in a multidisciplinary, preferably high-volume setting, it is equally as important for the nonspecialist general surgeon to be familiar with lipoma and its doppelganger-the well-differentiated liposarcoma.

Solid Primary Retroperitoneal Masses in Adults: An Imaging Approach

Mass lesions in the retroperitoneal space may be primary or secondary. Primary retroperitoneal mass lesions are relatively uncommon as compared to pathology that arises secondarily from retroperitoneal organs. These may be solid or cystic lesions. The overlapping imaging features of various solid primary retroperitoneal tumors make the diagnosis difficult, and hence, histopathology remains the mainstay of diagnosis. This paper provides a brief review of the anatomy of the retroperitoneal space and provides an algorithmic approach based on cross-sectional imaging techniques to narrow down the differential diagnosis of solid primary retroperitoneal masses encountered in the adult population.

Hereditary and Sporadic Pheochromocytoma: Comparison of Imaging, Clinical, and Laboratory Features

BACKGROUND. A considerable fraction of pheochromocytomas initially suspected to be sporadic, whether or not symptomatic, are a result of germline mutations. OBJECTIVE. The purpose of this article is to compare imaging features between hereditary and sporadic pheochromocytomas. METHODS. This retrospective study included 71 patients (39 women, 32 men; median age, 48 years) who underwent adrenal pheochromocytoma resection from January 2002 to October 2021 after preoperative CT or MRI. Two radiologists independently reviewed examinations to assess features of the largest resected pheochromocytoma. Interreader agreement was assessed by prevalence-adjusted bias-adjusted kappa coefficients; a third radiologist resolved discrepancies for further analysis. Genetic testing was used to classify pheochromocytomas as hereditary or sporadic and to classify hereditary pheochromocytomas by germline mutation clusters. Symptoms associated with pheochromocytomas and preoperative biochemical laboratory values were recorded. Groups were compared using Kruskal-Wallis, Fisher exact, and chi-square tests, and false-discovery rate-adjusted p values were computed to account for multiple comparisons. RESULTS. Hereditary pheochromocytoma (n = 32), compared with sporadic pheochromocytoma (n = 39), was associated with younger median age (38 vs 52 years, p = .001) and smaller median size (24 vs 40 mm, p < .001). Interreader agreement for CT and MRI features, expressed as kappa, ranged from 0.44 to 1.00. Hereditary and sporadic pheochromocytoma showed no difference in frequency of calcifications, hemorrhage, cystic change/necrosis, or macroscopic fat on CT, or in frequency of hemorrhage, cystic change/necrosis, macroscopic fat, or microscopic fat on MRI (p > .05). When combining CT and MRI, cystic change/necrosis was observed in 35% of hereditary versus 67% of sporadic pheochromocytomas (p = .10). Hereditary pheochromocytoma, compared with sporadic, had lower frequency of symptoms (31% vs 74%; p = .004) and lower 24-hour urinary normetanephrines (1.1 vs 5.1 times upper limits of normal, p = .006). Among hereditary pheochromocytomas, cystic change/necrosis (when assessable on imaging) was present in 18% and 45% of those with cluster 1 (n = 11) and cluster 2 (n = 21) germ-line mutations, respectively. CONCLUSION. Hereditary pheochromocytomas, compared with sporadic, are detected at a younger age and smaller size, produce lower 24-hour urinary normetanephrines, are less often symptomatic, and may less frequently show cystic change/necrosis. CLINICAL IMPACT. Imaging findings may complement clinical and biochemical features in raising suspicion for a previously unsuspected germline mutation in patients with pheochromocytoma.

Pancreatic liposarcoma: a case report

An 81-year-old woman who had undergone total thyroidectomy for papillary thyroid cancer 12 years earlier was found to have a tumor in the tail of the pancreas. Four years earlier, skin, lung, and mediastinal lymph node metastases had appeared. Computed tomography (CT) showed a mass 26 mm in diameter in the tail of the pancreas. Thereafter, the pancreatic tumor increased in size, while the lung metastases remained stable. Unenhanced CT at the time of first detection showed that the tumor was heterogeneous, with low-attenuation areas indicating fat components. As the tumor grew, the fat components became unclear. Laparoscopic distal pancreatectomy and splenectomy were performed. The tumor was diagnosed as dedifferentiated liposarcoma with a well-differentiated liposarcoma component at the tumor margin. The pancreas is an extremely rare site of primary liposarcoma. In the present case, a pancreatic liposarcoma appeared during follow-up of thyroid cancer, and the changes over time were able to be observed with CT.

Differentiation between heterogeneous adrenal adenoma and non-adenoma adrenal lesion with CT and MRI

PURPOSE

To assess whether heterogeneous adrenal adenomas can be distinguished from heterogeneous non-adenomas with Computed Tomography (CT) and/or Magnetic Resonance Imaging (MRI).

METHOD

From 2009 to 2019, 980 consecutive adrenalectomies were retrospectively identified. Patients without adequate CT/MRI, with homogeneous and/or < 1 cm lesions were excluded. Differences between adenomas and non-adenomas were analyzed using Chi-square, Student t or Fischer tests, and interobserver agreement using weighted kappa test or intraclass correlation coefficient. Independent variables associated with adenomas were searched for using multivariable analysis. Area under the receiver operating characteristic curve (AUC) of the final model and its diagnostic performances were calculated.

RESULTS

Final population comprised 183 patients (106 women, 77 men, mean age 53.2 ± 14.4 years) with 124 non-adenomas and 59 heterogeneous adenomas. Macroscopic or microscopic fat on CT/MRI allowed diagnosis of adenoma with 98% specificity and 63% sensitivity. Interobserver agreement was almost perfect for macroscopic fat (k = 0.82; 95% CI 0.66; 0.94) and substantial for microscopic fat (k = 0.75; 95% CI 0.62; 0.86). A multivariable model including micro- or macroscopic fat [Odds ratio (OR) 81.19; 95% CI 20.17; 572.27], diameter < 5.5 cm (OR 7.32; 95% CI 2.17; 31.28), calcifications (OR 5.68; 95% CI 2.08; 16.18), and hemorrhage (OR 3.10; 95% CI 0.70; 15.35) had an AUC of 0.91 (95% CI 0.86; 0.96), 71% (42/59, 95% CI 58; 82) sensitivity, 93% (115/124; 95% CI 87; 97) specificity, and 86% (157/183; 95% CI 79; 90) accuracy for the diagnosis of adenoma.

CONCLUSION

A multivariable model enables CT/MR diagnosis of heterogeneous adenomas. Presence of microscopic fat, even if partial, in a heterogeneous mass is highly specific of adenoma.

Giant retroperitoneal lipoma presenting with abdominal distention: A case report and review of the literature

BACKGROUND

Retroperitoneal lipomas are extremely rare tumors and tend to be large in size (> 10 cm) when diagnosed, causing various clinical manifestations. Preoperative diagnosis of retroperitoneal lipomas is difficult. There is a lack of relevant information about the management and prognosis of these benign tumors due to limited reports.

CASE SUMMARY

A 53-year-old woman who complained about progressive abdominal distention and aggravating satiety was referred to the gynecological outpatient department of Peking Union Medical College Hospital. Computerized tomography (CT) revealed an immense mass with fat density, measuring 28.6 cm× 16.6 cm in size. Adjacent organs, including the intestinal tract and uterus, were squeezed to the right side of the abdomen. An exploratory laparotomy was performed with suspicion of liposarcoma. Intraoperatively, a giant yellowish lobulated mass was found occupying the retroperitoneum and it was removed by tumor debulking. Postoperative histopathological results confirmed the diagnosis of retroperitoneal lipoma.

CONCLUSION

Retroperitoneal lipoma is a very rare condition and is difficult to differentiate from well-differentiated liposarcoma. Radiographic investigations, especially CT and magnetic resonance imaging, are important for preoperative diagnosis. Surgical resection is the fundamental treatment, which is difficult due to its size and relation to neighboring structures.

Fat-containing pelvic lesions in females

Pelvic tumors are common in females and have a broad differential diagnosis. The clinical management of pelvic tumors varies widely-from observation to surgical resection-and imaging plays a pivotal role in diagnosis and clinical decision-making in these cases. In particular, imaging can help determine the organ of origin and tissue content of these tumors, which are the most important steps to narrowing the differential diagnosis. Fat has a characteristic appearance and is often easily identified on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). The amount and distribution of intralesional fat varies in different types of tumors. Macroscopic intralesional fat is often easily recognized by its hyperechoic appearance on US and low attenuation on CT similar to subcutaneous fat. On MRI, macroscopic fat is hyperintense on T1-weighted (T1W) images, with characteristic signal loss on fat-saturated sequences and India-ink artifact on opposed-phase T1W images. Macroscopic fat is the hallmark of teratomas, which are the most common ovarian neoplasms. Uterine lipoleiomyomas, peritoneal loose bodies, intraperitoneal and extraperitoneal primary lipomatous tumors such as lipoma and liposarcomas, and extra-adrenal myelolipomas are other pelvic masses distinguished by the presence of macroscopic fat. However, the imaging diagnosis of pelvic masses containing minimal or microscopic fat, such as immature ovarian teratomas, steroid cell ovarian neoplasms, and extramedullary hematopoiesis, can present a diagnostic challenge owing to their nonspecific appearance on US or CT. Obtaining MRI with in-phase and opposed-phase dual-echo T1W sequences and depicting chemical shift artifacts can be helpful in distinguishing these lesions.

An extrahepatic hydatid cyst with the fat-fluid level

A hydatic cyst is a zoonosis caused by the larva of a tapeworm Echinococcus granulosus. The liver is the most commonly affected organ. Soft tissue localization has been reported in 2.3% of cases. Herein, we present a patient with a fat-containing hydatid cyst located in the left thigh. There are only a few reports in the literature on the presence of the fat-fluid level within a hydatid cyst. Previous studies have suggested that fat-containing hydatid cysts occur due to their cysto-biliary communication in the liver. In our case, we describe a fat-containing hydatid cyst in the extrahepatic location and discuss the pathophysiologic mechanism of fat inside it.

Bilateral extra-adrenal perirenal myelolipomas: a case report

Background

Myelolipomas are mesenchymal tumors usually involving the adrenal gland. They are a rare entity with incidence ranging from 0.08 to 0.4% as per autopsy reports. Only 15% of these are in extra-adrenal locations such as pelvis, retroperitoneum, mediastinum, lungs, stomach, liver, spleen and kidneys. Very few (only 3) cases of bilateral extra-adrenal perirenal myelolipomas have been reported until now; and one such case has been presented in our case report.

Case presentation

A 45-year-old male presented with abdominal distension and bilateral lower limb edema for 2 months. Renal functions were mildly deranged. Ultrasound was suggestive of perirenal masses. CT scan of the abdomen confirmed the diagnosis of bilateral extra-adrenal, perirenal myelolipoma. The differentials of lipomatous retroperitoneal tumors were considered. Core biopsy from perirenal masses revealed adipose tissue with interspersed hematopoietic precursors.

Conclusion

Extra-adrenal myelolipoma are rare tumors that are not known to have malignant potential and may be symptomatic only due to mass effect. Diagnosis can be confirmed by imaging in most cases. Histopathology may not be able to confirm malignancy even in sarcoma if sample is not taken from the appropriate site, usually non-fatty soft-tissue components. This rare case is presented in order to add to literature, the varied presentations of extra-adrenal myelolipomas.

Retroperitoneal lipoma, a rare cause of pelvic mass in women

Background:

Lipoma is a benign mesenchymal tumor of soft tissue that occurs in almost all parts of the body where fat normally exists. Retroperitoneal lipomas are very infrequent condition with about 20 cases represented in the literature since 1980. They usually present as an abdominal mass or with pressure symptoms to adjacent organs.

Case Presentation:

A 66-year-old, post-menopausal woman referred to Imam Hossein Medical Center due to abdominal pain. Abdominopelvic magnetic resonance imaging (MRI) revealed a large mass containing fat component without enhancement on the right side of the pelvis. Tumor markers were within normal ranges. The patient underwent laparotomy and a 12 cm retroperitoneal mass which was located on the iliopsoas muscle with extension into the inguinal canal was resected with pathology report of lipoma. There has been no recurrence after one year of follow-up since surgery.

Conclusion:

In the differential diagnosis of retroperitoneal pelvic mass at all ages, lipoma should be considered as a rare cause.

Adrenal myelolipomas

Adrenal myelolipomas are benign, lipomatous tumours with elements of myeloid cells, most of which present as adrenal incidentalomas and comprise 3·3-6·5% of all adrenal masses. Adrenal myelolipomas are usually unilateral (in 95% of cases), variable in size, most often found during midlife, and affect both sexes almost equally. On imaging, adrenal myelolipomas show pathognomonic imaging features consistent with the presence of macroscopic fat. Large adrenal myelolipomas can cause symptoms of mass effect, and can occasionally be complicated by haemorrhage. In the event of a concomitant adrenal cortical adenoma or hyperplasia, adrenal hormone excess might be detected in patients with adrenal myelolipoma. Patients with congenital adrenal hyperplasia exhibit a higher prevalence of adrenal myelolipomas than other patient groups, and are at risk of developing large and bilateral lesions. This Review discusses the pathogenesis, clinical presentation, and management of adrenal myelolipomas.

Diagnosis strategy of adipocytic soft-tissue tumors in adults: a consensus from European experts

Fat-containing tumors are very commonly found in daily practice with benign lipoma accounting for the majority of superficial tumors. Overlap in imaging findings between benign and intermediate or malignant fat-containing tumor is common. Guidelines recommend a core needle biopsy (CNB) for all deep tumors, and superficial tumors over 3 cm. However, specific strategy for diagnosis and referral to a sarcoma center should be applied on adipocytic tumors. The aim of this consensus statement is to provide a specific algorithm for adipocytic tumors, to discriminate patients who do require a CNB for preoperative diagnosis from those who can simply undergo active surveillance or a simple excision.

Radiologic-Pathologic Correlation of Primary Retroperitoneal Neoplasms

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

Potential application value of PET/computed tomography in retroperitoneal leiomyosarcoma and a literature review

OBJECTIVE

To analyze the fluorine-18 fludeoxyglucose PET/computed tomography (18F-FDG PET/CT) findings of retroperitoneal leiomyosarcoma (RLMS) and the role of this method in differentiating between benign and malignant masses and classifying the malignant degree to improve the understanding of this rare disease.

METHODS

Eight leiomyomas (A group), 13 RLMSs (B group), and 20 postoperative recurrence/metastasis RLMSs (C group) were enrolled. PET/CT features of B group were analyzed. The differences of metabolic parameters between three groups were compared, receiver operating characteristic (ROC) curve analysis was performed to group A and B, and correlation analysis was performed to subgroup B.

RESULTS

(1) The RLMS patients were more likely to be female, and PET/CT showed a high degree of heterogeneous metabolism in the soft tissue mass. (2) The standardized uptake value (SUV) of RLMS were significantly higher than those of benign leiomyomas (P < 0.05). The area under the ROC curve was 0.909, the sensitivity and specificity for diagnosing RLMS were 0.923 and 0.750, respectively, The SUVmax and SUVstd of primary RLMS were moderately associated with the Ki67 index. The mean SUVmax in the G1, G2 and G3 subgroups increased successively (4.15 ± 0.35, 6.47 ± 0.83, and 10.13 ± 4.29, respectively). (3) Primary RLMS was characterized by local invasion, but hematogenous metastasis and lymph node metastasis were rare. Postoperative recurrence/metastasis of RLMS was characterized by local recurrence and hematogenous metastasis, but lymph node metastasis was rare.

CONCLUSION

PET/CT has potential value in the preoperative staging, benign and malignant differentiation, malignant degree classification and postoperative follow-up of RLMS.

Incidental Adrenal Nodules

Incidentally detected adrenal nodules are common, and prevalence increases with patient age. Although most are benign, it is important for the radiologist to be able to accurately determine which nodules require further testing and which are safely left alone. The American College of Radiology incidental adrenal White Paper provides a structured algorithm based on expert consensus for management of incidental adrenal nodules. If further diagnostic testing is indicated, adrenal computed tomography is the most appropriate test in patients for nodules less than 4 cm. In addition to imaging, biochemical testing and endocrinology referral is warranted to exclude a functioning mass.

Diagnostic approach to primary retroperitoneal pathologies: what the radiologist needs to know

Retroperitoneal soft tissue lesions represent a wide range of disease processes with overlapping imaging findings. Familiarity with the CT and MR characteristics of these conditions is important to guide clinical evaluation. We review the tissue types, characteristic clinical, demographic, and imaging features of retroperitoneal tumors and tumor-like non-neoplastic conditions with CT and MR correlation, including anatomic and imaging clues, and provide a diagnostic approach to aide the radiologist in making a specific diagnosis.

Presacral Myelolipoma: The Usefulness of a 99mTc-Albumin Nanocolloid Scintigraphy

Myelolipoma is a rare mesenchymal tumor consisting of adipose tissue and hematopoietic cells. Found usually in the adrenal region, however, few cases have been reported in extra-adrenal regions, most frequently in the presacral region. It is important to recognize such tumor, as it can attain massive size and causes pressure symptoms, and needs to be differentiated from malignant tumors, including liposarcomas. Although CT and MRI can suggest a diagnosis of myelolipoma, these are not conclusive. The hematopoietic cells are enhanced by a Tc-albumin nanocolloid scintigraphy and help to distinguish myolipoma from other entities.

Unusual appearance of an adrenal ganglioneuroma

Ganglioneuromas are rare tumors that occur spontaneously or arise from a poorly differentiated neuroblastic tumor. Although they are typically described in the pediatric population, they can occur in adults. Ganglioneuromas are often discovered incidentally and their typical imaging appearance, although non-specific, is that of a well-defined solid mass. We are presenting a case of a fat-containing adrenal lesion in a 53-year-old male. The extensive lipomatous changes within the lesion led to the presumption that it represented an adrenal myelolipoma. Pathology revealed a ganglioneuroma with extensive lipomatous changes. This is an uncommon presentation of an adrenal ganglioneuroma mimicking an adrenal myelolipoma. The diagnosis of an adrenal ganglioneuroma raises the possibility of syndromic associations for which patients may undergo genetic testing. We provide a review of typical imaging features of an adrenal ganglioneuroma and provide insight into the situations in which a ganglioneuroma can be suggested as a diagnostic consideration.

Renal Angiomyolipoma Mimicking a Well-Differentiated Retroperitoneal Liposarcoma

A 37-year-old Burmese woman presented with an incidentally found retroperitoneal fat-containing tumor. The tumor was 9 cm in the longest diameter, surrounding the right kidney, and composed of homogenous adipose tissue with thickened septum-like structures and spotty nonadipose structures, which were enhanced on contrast-enhanced computed tomography and magnetic resonance imaging. The tumor did not show either a beak sign or synchronous angiomyolipoma-like lesion in the kidneys. The tumor had irregular septa, thin blood vessels, and spotty small soft-tissue nodules. The tumor did not contain any heterogeneously enhanced solid lesions suspicious for dedifferentiated liposarcomas. Based on these imaging findings, a clinical diagnosis of a well-differentiated liposarcoma was made. Under the consensus of a multidisciplinary cancer board, she was recommended to undergo core-needle biopsy to confirm the clinical diagnosis. However, she declined to undergo biopsy for financial reasons. She underwent kidney-sparing retroperitoneal tumor resection. Histopathologically, the tumor was an angiomyolipoma with positive immunostaining for HMB45 and Melan A. The present case suggests the importance of core-needle biopsy prior to surgical intervention for retroperitoneal fat-containing tumors.

Recurrent giant retroperitoneal liposarcoma with 10 years follow up. Case report and review of literature

INTRODUCTION

This case is of a patient with a recurrent giant retroperitoneal liposarcoma, followed-up and operated multiple times over 10 years. We report this case because of its rarity and review all previous articles reporting "Giant Retroperitoneal Liposarcoma" in the English literature.

CASE DESCRIPTION

A 70 years old man presented to our clinic for dizziness and fatigue. He was incidentally found to have a large retroperitoneal mass filling all the length of the abdominal cavity and shifting all intraabdominal viscera and kidney to the left side. En bloc excision of a 50 × 30 × 18 cm, 9 kg tumor was performed. Final pathology revealed a well-differentiated liposarcoma. Five years later, the patient was reoperated for recurrence and a well-differentiated liposarcoma was excised in 2 pieces (the biggest measuring 14 × 11 × 7 cm) along with the appendix. Four years later the patient was operated on again for a second recurrence, and again a well-differentiated liposarcoma (16 × 10 × 7 cm) extending into the right inguinal canal was excised. One year thereafter, the patient was diagnosed with a third recurrence (22 × 12 cm).

DISCUSSION

Retroperitoneal Liposarcomas are rare tumors, presenting with different histological differentiation. They are diagnosed using multiple imaging modality, mainly CT scan, and it is confirmed by percutaneous large core needle biopsy. R0 Surgical excision remains the proper treatment for non-metastatic tumors, which may necessicate multiorgan resection. They rarely grow to reach a large size and be labled as "Giant Retroperitoneal Liposarcoma".

Retroperitoneal tumors: Review of diagnosis and management

Retroperitoneal tumors are extremely rare tumors occurring in the retroperitoneum. Retroperitoneal tumors are divided into benign tumors and malignant tumors, including retroperitoneal sarcoma. Approximately 70-80% of primary retroperitoneal soft-tissue tumors are malignant; however, these only account for 0.1-0.2% of all malignancies. Retroperitoneal sarcoma is an orphan malignant disease with a low incidence. The information on benign retroperitoneal tumors is limited. The American Joint Committee on Cancer/TNM classification updated to the 8th edition in 2017. In 2010, three new drugs for soft tissue sarcoma were approved based on the results of phase III trials, but the histological subtypes of the patients enrolled in the trials of each drug differed. Recently, in addition to surgery for retroperitoneal sarcoma, the effectiveness of perioperative radiation therapy has become interesting. For malignant retroperitoneal tumors and retroperitoneal sarcoma, survival improvement and locoregional recurrence prevention can be undertaken by carrying out surgery to secure negative margins with wide and combined resection of some adjacent organs, and cooperation with a trained medical team comprising of radiologists, pathologists and medical oncologists in centralized hospitals. Some clinical trials aimed at further improving treatment results by adding preoperative chemotherapy and radiation therapy based on histological confirmation using a correct needle biopsy are in progress. In recent years, molecular profiling has been used to select eligible patients for chemotherapy. In the future, precision medicine with next-generation sequencing technology will be expected among the diverse and potential future treatments for retroperitoneal sarcoma. In this review, we summarized the current state of retroperitoneal tumors and retroperitoneal sarcoma.

Perinephric myxoid pseudotumor of fat: A very rare entity that can mimic a renal cyst and retroperitoneal liposarcoma on imaging

We present a case of perinephric myxoid pseudotumor of fat, a rare benign entity that often occurs in patients with non-neoplastic renal disease. In our case, an 80 year old man with end-stage renal disease was imaged over the course of 5 years during evaluation for renal transplantation. Imaging identified a left perinephric mass whose appearance over time and on different imaging modalities variably suggested a simple cyst, cystic neoplasm, and liposarcoma. Contrast enhanced examination was necessary to discern the solid nature of this mass, and ultimately, tissue sampling with histopathologic evaluation and molecular testing were required to make the diagnosis of myxoid pseudotumor of fat and exclude the imaging mimics.

An unusual finding of giant fat-rich retroperitoneal masses in a patient with Graves' disease

We report the case of a 48-year-old man who was unexpectedly found by abdominal ultrasonography to have large retroperitoneal masses accompanied by Graves' disease. Computed tomography and magnetic resonance imaging further demonstrated giant fat-rich soft masses arising within both renal sinuses. Histopathological examination of the mass was performed twice at 5-year intervals, with both examinations indicating fatty tissue cells with chronic fibrous panniculitis. Intravenous pulse therapy and successive oral glucocorticoid therapy were ineffective against Graves' ophthalmopathy or mass lesion. An antithyroid hormone regimen was followed by subtotal thyroid resection, leading to improvements in hyperthyroidism. Mass growth then attenuated slowly as the thyroid hormones returned to normal levels. The long-term follow-up of this patient should carefully monitor the appearance of warning signs such as mass effects.

Non-adrenal tumors of the adrenal area; what are the pitfalls?

Discovery of an adrenal mass is nowadays a frequent situation. While adrenal tumors can cause a variety of symptoms, more often than not they are diagnosed incidentally on imaging exams such as CT-scan or MRI performed for another purpose. However, any retroperitoneal supra-renal mass can have an extra-adrenal origin. Indeed, operated non-adrenal masses initially but wrongly diagnosed as an adrenal disease represent about 3.5% of adrenalectomies. These differential diagnoses principally include retroperitoneal tumors that are malignant in two thirds of cases (lymphomas, sarcomas, neurogenic or germinal tumors), and more rarely vascular anomalies or congenital malformations, which are most frequently left-sided due to the wide variety of anatomical structures surrounding the left adrenal gland. Several lesions can originate from the adrenal gland or be located near the gland (paraganglioma, ganglioneuroma). Even though unilateral adrenalectomy is associated with low morbidity, ignorance of these differential diagnoses can cause ill-adapted management; overly conservative surgery in case of sarcoma is one example. Some of these lesions have characteristic clinical or imaging features (cystic lymphangioma, angiomyolipoma…). In other cases, assessment of hormonal secretion is required and additional exams (MRI, percutaneous biopsy, PET-scan with 18-Fluorodeoxyglucose) can correct an erroneous diagnosis. The above diagnostic approach allows appropriate management (with or without surgery). The purpose of this review was to highlight the main differential diagnoses of adrenal masses, to describe their characteristics, and to discuss their therapeutic management.

Comprehensive Review of Abdominopelvic Mesenchymal Tumors With Radiologic Pathologic Correlation and Update on Current Treatment Guidelines-Part 2

Soft-tissue sarcomas are a diverse group of rare mesenchymal malignancies accounting for only 1% of all solid adult malignancies. These have been categorized in 12 broad groups by the World Health Organization (WHO) with their recent update in 2013. Majority of them lack specific imaging features serving as imaging conundrums for a radiologist. These are often large masses at presentation as they are asymptomatic or cause vague clinical symptoms. These tumors are challenging for surgeons as well as they find it difficult to achieve complete resection because of complex intra-abdominal anatomy and their close relationship with critical structures. Often, a multidisciplinary approach is required to decide on the most appropriate management for these complex cases so as to provide optimal patient care. Knowledge of the WHO classification, pathologic features, and treatment options available helps the radiologist make a meaningful contribution in multidisciplinary discussions of such cases and overall patient care. Liposarcoma (well-differentiated and dedifferentiated liposarcomas), leiomyosarcoma, and gastrointestinal stromal tumor are the 3 most common primary intra-abdominal sarcomas. In part 1 of this article, general features of soft-tissue sarcomas and some of the common tumors from WHO category 1-4 found in abdomen and pelvis are discussed. Part 2 will focus on common tumors from remainder of the WHO categories.