Retroperitoneal tumors and lymphadenopathy

The retroperitoneum is the space between the parietal peritoneum anteriorly and the transversalis fascia posteriorly. Most retroperitoneal tumors arise from mesenchyme, neurogenic tissue, or embryonic rests. By this definition and by including lymph nodes as a retroperitoneal organ, lymphoma is not considered a primary retroperitoneal tumor.     

Retroperitoneal tumors and lymphadenopathy

The retroperitoneum is the space between the parietal peritoneum anteriorly and the transversalis fascia posteriorly. Most retroperitoneal tumors arise from mesenchyme, neurogenic tissue, or embryonic rests. By this definition and by including lymph nodes as a retroperitoneal organ, lymphoma is not considered a primary retroperitoneal tumor. The opinions or assertions contained herein are the private views of the author and are not to be construed as official or reflecting the view of the Uniformed Services University of the Health Sciences, the Department of the Navy, or the Department of Defense     

A massive retroperitoneal mature teratoma from a “burned-out” testicular teratoma and seminoma

Germ cell tumors are the most common nonhematologic malignancy of young men which often present with metastasis to the retroperitoneum, however a primary retroperitoneal mass should also be considered. The case presented herein reports a 42-year-old male presenting with a massive heterogenous retroperitoneal mass determined to be a mature cystic teratoma. Further investigation revealed a multifocal right testicular mass containing both a viable pure seminoma and a fibrous scar demonstrating germ cell neoplasia in situ thus representing the rare phenomenon of a “burned-out” mixed germ cell testicular tumor. When the radiologist is faced with a large retroperitoneal fat-containing mass, the differential includes a renal angiomyolipoma, liposarcoma, or germ cell tumor (whether primary or secondary). If pathology reveals a germ cell tumor, it is imperative to perform a thorough evaluation of the gonads, as it is much more common for a retroperitoneal germ cell tumor to be a metastasis from the gonads, rather than primary in origin.     

Anterior protrusion of retroperitoneal processes. A mimic of lesser sac or gastrohepatic masses

The space between the left lobe of the liver and the lesser curvature of the stomach normally contains intraperitoneal structures. These include the gastrohepatic recess of the greater peritoneal cavity, the medial recess of the lesser sac and the interposed gastrohepatic ligament. An anterior protrusion of retroperitoneum can project into this space, dorsal to the posterior reflection of the medial compartment of the lesser sac. Tumors that extend into this fossa are anterior and medial to the fundic and upper body region of the stomach. These tumors may cause confusion regarding their origin if the radiologist is not aware of the existence of this retroperitoneal protrusion. Between 1982, and 1986, 183 patients with pancreatic cancer were hospitalized at our institution, 63 of whom had computed tomography (CT) scans of the abdomen. Four of these patients (6.3%) demonstrated direct tumor extension anterior to the stomach. During this same period, four large benign retroperitoneal tumors also exhibited this finding. Masses in the gastrohepatic interval between the liver and stomach can be extensions of retroperitoneal processes and should not be assumed to represent intraperitoneal involvement.     

Retroperitoneal malignant fibrous histiocytoma: The angiographic and computed tomographic features of an unusual tumor

Malignant fibrous histiocytomas are uncommon retroperitoneal soft tissue tumors. We report a case of a malignant fibrous histiocytoma of the retroperitoneum that was angiographically hypervascular and indistinguishable from renal cell carcinoma. Computerized tomography of the abdomen demonstrated extensive psoas muscle infiltration by tumor. This feature may be useful in differentiating a renal cell carcinoma from a primary retroperitoneal sarcoma.     

原发性腹膜后肿瘤的影像学诊断

原发性腹膜后肿瘤来源复杂，周围脏器多。旨在探讨影像学检查的诊断价值。材料与方法：回顾性分析４６例病理证实的腹膜后肿瘤的Ｘ线、ＣＴ及超声表现，并与手术所见作对照分析。Ｂ超及ＣＴ具较高的定位诊断价值。ＣＴ可较好地显示肿瘤的境界及质地，对腹膜后肿瘤的定性诊断有一定的帮助。     

Gastrointestinal stromal tumor of the retroperitoneum: CT and MR findings

Gastrointestinal stromal tumor (GIST) is a non-epithelial neoplasm arising from the wall of the gastrointestinal (GI) tract. Although the majority of GISTs are located in the GI tract, some GISTs occur in the omentum, mesentery and retroperitoneum. GIST arising in the retroperitoneum is extremely rare, and its radiological findings have not been well described. We report a case of primary retroperitoneal GIST and discuss its imaging findings.     

Retroperitoneal and pelvic hemangiopericytomas: clinical, radiologic, and pathologic correlation

Seventeen cases of hemangiopericytoma of the retroperitoneum were retrospectively analyzed for demographic, morphologic, and radiologic features. These tumors were found in all age groups (2 months to 72 years) and occurred in similar numbers of male and female patients. The tumors tended to be large (11 were greater than 8 cm), were well encapsulated, and occurred less frequently in the pelvic retroperitoneal space (six cases) than in abdominal retroperitoneum (11 cases). All tumors were bulky enough to displace part of the gastrointestinal tract, with only two being inoperable. The most distinctive radiologic feature was hypervascularity (found on 11 of 11 angiograms). Other nondiscriminating radiologic features included well-defined margins and necrosis, with nondistinctive amorphous calcification identified in one case. Angiographic or computed tomographic demonstration of hypervascularity in a retroperitoneal tumor is more suggestive of hemangiopericytoma than of a liposarcoma or malignant fibrous histiocytoma, two of the more common tumors of this region.     

Neurogenic tumors in the abdomen: tumor types and imaging characteristics.

There is a broad spectrum of neurogenic tumors that involve the abdomen. These tumors can be classified as those of (a) ganglion cell origin (ganglioneuromas, ganglioneuroblastomas, neuroblastomas), (b) paraganglionic system origin (pheochromocytomas, paragangliomas), and (c) nerve sheath origin (neurilemmomas, neurofibromas, neurofibromatosis, malignant nerve sheath tumors). Abdominal neurogenic tumors are most commonly located in the retroperitoneum, especially in the paraspinal areas and adrenal glands. All of these tumors except neuroblastomas and ganglioneuroblastomas are seen in adult patients. Abdominal neurogenic tumor commonly manifests radiologically as a well-defined, smooth or lobulated mass. Calcification may be seen in all types of neurogenic tumors. The diagnosis of abdominal neurogenic tumor is suggested by the imaging appearance of the lesion, including its location, shape, and internal architecture. Benign and malignant neurogenic tumors are difficult to differentiate unless distant metastatic foci are seen. For malignant tumors, imaging modalities other than computed tomography (CT) and magnetic resonance (MR) imaging may be necessary for staging. However, because most neurogenic tumors in adults are benign, CT and MR imaging can be used to develop a differential diagnosis and help determine the immediate local extent of tumor. Copyright RSNA, 2003.     

CT characteristics of primary retroperitoneal neoplasms in children

Primary retroperitoneal neoplasms are uncommon in children. Retroperitoneal neoplasms are either mesodermal, neurogenic, germ cell ectodermal or lymphatic in origin. In general, primary retroperitoneal neoplasms in children have different spectrum and prevalence compared to those in adults. Neuroblastoma, rhabdomyosarcoma, benign teratoma and lymphoma are the common retroperitoneal neoplasms. In this review, the clinical and CT futures of common retroperitoneal neoplasms in children are described. Coarse, amorphous, and mottled calcification are very common in neuroblastoma. Paraganglioma tends to show marked and early enhancement and may present with clinical symptoms associated with the excess catecholamine. Sarcomas are often very large and have heterogeneous appearance. Imaging cannot be reliably used to identify the type of retroperitoneal sarcomas due to overlapped radiographic features. In children, lipoblastoma is the most common lipomatous tumor in the retroperitoneum. The percentage of visible fat in tumor varies depending on the cellular composition of the lesion. The CT characteristics of teratoma are quite variable, which may be cystic, solid, on a combination of both. Typically teratoma appears as a large complex mass containing fluid, fat, fat-fluid level, and calcifications. Lymphoma is often homogeneous on both enhanced and unenhanced CT scans. Necrosis and calcification are rare on CT. In conclusion, making a final histological diagnosis of retroperitoneal tumor base on CT features is not often possible; however, CT can help to develop a differential diagnosis and determine the size and extent of the retroperitoneal neoplasms.     

Retroperitoneal oncocytoma: case report and review of the imaging features

Oncocytomas are uncommon tumours that occur in a number of specific anatomical locations within the head, neck, chest, abdomen and pelvis. When occurring in the retroperitoneum, oncocytomas almost always arise from either the kidney or adrenal gland. With this case we present the imaging findings of an exceptionally rare retroperitoneal oncocytoma whose site of origin is neither the kidney nor adrenal gland.     

Radiologic findings of peripheral primitive neuroectodermal tumor arising in the retroperitoneum

OBJECTIVE: The purpose of this article is to present the radiological findings of peripheral primitive neuroectodermal tumors that arise in the retroperitoneum. CONCLUSION: Peripheral primitive neuroectodermal tumors (PNETs) arising in the retroperitoneum tend to be large and aggressive. Although the imaging appearance of peripheral PNETs is nonspecific, these tumors should be considered in the differential diagnosis when one encounters a large retroperitoneal mass with aggressive features.     

Primary retroperitoneal neoplasms: How close can we come in making the correct diagnosis

The primary retroperitoneal tumors form a rare and diverse group of neoplasms, the origin of which is independent of the various retroperitoneal organs and unrelated to systemic diseases, such as lymphomas, lymphadenopathy, or metastases. Radiologic investigation, mainly cross-sectional imaging and, to a lesser extent, angiography is essential in the diagnosis and management of these tumors. The radiologist often is challenged to identify the origin and specific tissue composition of the imaged neoplasms. When the radiologic findings are combined with patient information and clinical data, the correct diagnosis may be made in many cases. Imaging-guided percutaneous needle biopsy further enhances the diagnostic yield of the various imaging modalities by establishing the diagnosis without the need for exploration.     

Primary retroperitoneal neoplasms: how close can we come in making the correct diagnosis.

The primary retroperitoneal tumors form a rare and diverse group of neoplasms, the origin of which is independent of the various retroperitoneal organs and unrelated to systemic diseases, such as lymphomas, lymphadenopathy, or metastases. Radiologic investigation, mainly cross-sectional imaging and, to a lesser extent, angiography is essential in the diagnosis and management of these tumors. The radiologist often is challenged to identify the origin and specific tissue composition of the imaged neoplasms. When the radiologic findings are combined with patient information and clinical data, the correct diagnosis may be made in many cases. Imaging-guided percutaneous needle biopsy further enhances the diagnostic yield of the various imaging modalities by establishing the diagnosis without the need for exploration.     

盆部原发肿瘤CT表现特征及其解剖学基础

目的分析盆部原发肿瘤CT增强表现特征，探讨产生各种影像表现的病理学和解剖学基础。方法回顾性分析14例经病理学证实的盆部原发肿瘤CT增强表现，包括病灶大小、密度、边缘、强化特征，肿块所在的解剖部位及其与邻近组织器官和间隙的关系等。结果良性肿瘤3例，恶性肿瘤11例。肿块位于盆腹膜腔和腹膜外间隙各6例，盆腹膜腔和腹膜外间隙同时受累2例。CT增强表现为实质性8例，囊实性6例；均匀强化3例，不均匀强化11例。肿块周围脂肪间隙清晰和受侵犯各7例。4例病灶内出现钙化，其中良性畸胎瘤2例，恶性畸胎瘤和类癌各1例。结论CT增强扫描能准确判断盆部原发肿瘤的解剖位置及其与邻近解剖结构的毗邻关系，初步判断肿瘤的良恶性，对畸胎瘤能做出比较明确的定性诊断。     

原发性肠系膜肿瘤的CT诊断

目的：讨论原发性肠系膜肿瘤的CT表现,提高该病的CT诊断率。方法：21例经手术病理证实的原发性肠系膜肿瘤,其中良性8例,恶性13例,分析其CT征象。结果：原发性肠系膜肿瘤多单发,体积较大,与肠管关系密切,多被肠管包绕,肿块常推压腹膜后脏器移位,但两者常有脂肪间隙存在,体积较大的肿瘤多密度不均匀,良性肠系膜肿瘤多数边缘光滑、形态规则,恶性肠系膜肿瘤多数边缘不光滑,常伴大片低密度坏死。结论：CT对原发性肠系膜肿瘤的定位具有重要价值,对于良性及恶性肿瘤的鉴别亦有较大帮助,但不易明确其组织学类型。     

Retroperitoneal neoplasms within the perirenal space in infants and children: Differentiation of renal and non-renal origin in enhanced CT images

Purpose

To retrospectively demonstrate the specific CT findings of retroperitoneal neoplasms to diagnosis and differential diagnosis renal and non-renal tumors within the perirenal space in infants and children.

Materials and methods

We retrospectively reviewed the clinical data and CT images of 42 consecutive patients with surgically and pathologically proven retroperitoneal neoplasms within the perirenal space. The patients were divided into renal tumors group (n = 16) and non-renal tumors group (n = 26). The former included nephroblastoma (n = 15) and renal lymphoma (n = 1), while the latter included neuroblastoma (n = 12), retroperitoneal teratoma (n = 6), adrenal ganglioneuroma (n = 4), retroperitoneal lymphoma (n = 2), ectopic pheochromocytoma (n = 1) and adrenal cortical carcinoma (n = 1). The clinical information of these patients and the major CT imaging findings which were related to lesion localization in the two groups were compared and statistically analyzed using Pearson Chi-Square Test and Risk Estimate.

Results

The mean diameter of tumors was 9.82 ± 6.13 cm (n = 42 range: 2.3-32 cm). The demographic data and chief clinical symptoms between the renal tumor group and the non-renal tumor group showed no statistically significant differences (P > 0.05). 30.8% (8/26) of non-renal tumor patients presented elevated urinary vanillylmandelic acid (VMA) level, while no patient showed elevated VMA in renal tumor group (P < 0.05). Some CT imaging signs of the renal tumors including “crescent sign” (odds ratio, OR = 52), “beak sign” (OR = 84), “embedded organ sign” (OR = 84), and “prominent feeding artery sign” (OR = 36) showed significantly higher incidence when compared to the non-renal tumors (P < 0.001). The sign of “renal displacement and renal axis rotation” (OR = 0.059) was seen in 23 of 26 (88.5%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P < 0.001). The sign of “extra-renal central plane of tumor” (OR = 0.038) was displayed in 24 of 26 (92.3%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P < 0.001). The CT findings such as “pseudocapsule” (OR = 38.5), “necrosis and cystic change” (OR = 11.2), “vascularity” (OR = 16.867), “distant metastasis” (OR = 5.96), and “inferior vena cava tumor thrombus” which were thought to be characteristic of renal tumors were observed with significant higher incidence in renal tumors group than in the non-renal tumors group (P < 0.05); while CT signs of “irregular mass” (OR = 0.045) and “intratumoral calcifications” (OR = 0.065) were observed with lower incidence in renal tumors group than in the non-renal tumors group (P < 0.05).

Conclusion

The “crescent sign”, “beak sign”, “embedded kidney sign” and “renal arteries feeding” are the most specific CT signs suggestive of renal tumors and distinguish them from non-renal origin tumors within the perirenal space. Other CT signs, such as “pseudocapsule”, “hypervascular tumors” and “Inferior vena cava tumor thrombus”, when present, tumors of renal origin are strongly suggested. On the other hand, CT signs of “irregular mass”, “intratumoral calcifications”, and associated elevated urinary vanillylmandelic acid strongly suggest the non-renal tumors.     

Atypical radiological features of a leiomyosarcoma that arose from the ovarian vein and mimicked a vascular tumour

Leiomyosarcomas of the ovarian vein are extremely rare tumours. Most tumours are hypervascular and typically have a large avascular centre of necrosis. We experienced a case of a retroperitoneal leiomyosarcoma that arose from the ovarian vein with marked vascular proliferation and dilatation within the tumour. To the best of our knowledge, this is the first case report of a retroperitoneal leiomyosarcoma with an atypical vascular structure in the clinical literature.A leiomyosarcoma is a rare malignant tumour of the smooth muscle that arises in the alimentary tract, retroperitoneum, genitourinary tract or soft tissue. A primary leiomyosarcoma of vascular origin is a rare tumour, which arises most often from the inferior vena cava [1]. A few cases of leiomyosarcoma of the ovarian vein have been reported in previous studies [2–4]. Commonly, a retroperitoneal leiomyosarcoma is seen as a large mass containing a prominent cystic necrotic area. Recently, we experienced a case of a retroperitoneal leiomyosarcoma that arose from the right ovarian vein and had multiple intratumoural dilated vessels. In this case report, we describe the imaging findings of this tumour and review the relevant literature.     

恶性纤维组织细胞瘤影像征象分析及诊断

目的:探讨恶性纤维组织细胞瘤(MFH)的CT及MRI征象,提高对该病的诊断水平.方法:搜集15例经手术病理确诊的MFH影像学资料进行回顾性分析,其中12例行CT检查,4例行MRI检查,2例行CT与MRI检查.结果:6例瘤体位于四肢,类圆形,边界模糊;其中2例MRI表现为T1WI呈等或稍低信号,T2 WI稍高混杂信号;其...     

腹膜后原发少见肿瘤的CT表现及其诊断价值

目的探讨腹膜后原发性肿瘤的CT特点,试图进一步提高对该类病变的认识水平。资料与方法回顾性分析经病理证实的28例腹膜后肿瘤的CT图像,观察肿块的位置、形态、大小及强化程度,并结合病理结果分析腹膜后肿瘤的CT特点。结果脂肪肉瘤3例,平滑肌肉瘤4例,恶性纤维组织细胞瘤3例,胃肠外恶性胃肠间质瘤2例,血管平滑肌脂肪瘤1例,神经鞘瘤4例,副神经节瘤2例,嗜铬细胞瘤3例,神经内分泌肿瘤1例,皮样囊肿1例,脉管瘤3例,囊性淋巴管瘤1例。其CT表现各不相同,CT定位腹膜后的准确率为71.42%(20/28),其中准确定性率为21.42%(6/28)。另有8例错误定位于腹膜后的脏器。结论腹膜后肿瘤种类多,其CT表现有很多重叠,但CT对腹膜后肿瘤的定位诊断率较高,对定性诊断及鉴别诊断也有一定的价值。