Venkateswar R. Surabhi

Benign Renal Neoplasms in Adults: Cross-Sectional Imaging Findings

OBJECTIVE A broad spectrum of benign renal neoplasms in adults shows characteristic ontogeny, histology, and tumor biology. Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Select benign tumors show characteristic anatomic distribution and imaging features. However, because of overlapping of findings between benign and malignant renal tumors, histologic evaluation may be required to establish a definitive diagnosis. Accurate preoperative characterization facilitates optimal patient management. CONCLUSION We attempt to provide a comprehensive, contemporary review of benign renal neoplasms that occur in adults, focusing on cross-sectional imaging characteristics.

A clinical and radiologic review of uncommon types and causes of pancreatitis.

Acute pancreatitis is one of the most common conditions for which emergent imaging is indicated. Alcohol consumption and cholelithiasis are the most common causes of acute pancreatitis in adults, whereas the majority of cases in children are idiopathic or secondary to trauma. A wide variety of structural and biochemical abnormalities may also cause pancreatitis. Although in some cases it is difficult to identify the specific cause of the disease radiologically, certain uncommon types of acute or chronic pancreatitis may have unique imaging features that can help the radiologist make an accurate diagnosis. These unusual types include autoimmune pancreatitis, groove pancreatitis, tropical pancreatitis, hereditary pancreatitis, and pancreatitis in ectopic or heterotopic pancreatic tissue. Pancreatitis may occasionally be seen in association with cystic fibrosis or pancreas divisum, or secondary to worm infestation of the pancreaticobiliary tree (eg, by Ascaris lumbricoides). In addition, primary pancreatic and duodenal masses may occasionally manifest as acute or recurrent acute pancreatitis. Knowledge of the classic imaging findings of these entities allows prompt recognition of the relevant pathologic condition, thereby preventing misdiagnosis and subsequent inappropriate or delayed management.

Mimics of Cholangiocarcinoma: Spectrum of Disease

Cholangiocarcinoma is the second most common primary malignant hepatobiliary neoplasm, accounting for approximately 15% of liver cancers. Diagnosis of cholangiocarcinoma is challenging and the prognosis is uniformly poor, with recurrence rates of 60%-90% after surgical resection. A wide spectrum of neoplastic and nonneoplastic conditions of the biliary tract may masquerade as cholangiocarcinoma, adding to the complexity of management in patients suspected to have cholangiocarcinoma. Mimics of cholangiocarcinoma constitute a heterogeneous group of entities that includes primary sclerosing cholangitis, recurrent pyogenic cholangitis, acquired immunodeficiency syndrome cholangiopathy, autoimmune pancreatitis, inflammatory pseudotumor, Mirizzi syndrome, xanthogranulomatous cholangitis, sarcoidosis, chemotherapy-induced sclerosis, hepatocellular carcinoma, metastases, melanoma, lymphoma, leukemia, and carcinoid tumors. These entities demonstrate characteristic histomorphology and variable clinicobiologic behaviors. The imaging findings of these disparate entities are protean and may be indistinguishable from those of cholangiocarcinoma. In most cases, a definitive diagnosis can be established only with histopathologic examination of a biopsy specimen.

Neoplastic and non-neoplastic proliferative disorders of the perirenal space: cross-sectional imaging findings.

The perirenal space, located between the anterior and the posterior renal fasciae, is shaped like an inverted cone with an apex that extends into the iliac fossa. Perirenal tumors and pseudotumors primarily originate either from the kidney or as part of a systemic disease process and have characteristic histopathologic features and biologic behavior. The lesions may be classified on the basis of their distribution and imaging features as solitary soft-tissue masses (renal cell carcinoma, lymphangioma, hemangioma, and leiomyoma), rindlike soft-tissue lesions (lymphoma, retroperitoneal fibrosis, and Erdheim-Chester disease), masses containing macroscopic fat (angiomyolipoma, liposarcoma, myelolipoma, and extramedullary hematopoiesis), and multifocal soft-tissue masses (metastases, plasma cell tumors). Because of overlap in imaging findings among these diverse perirenal lesions, a definitive diagnosis in most cases can be established only at histopathologic analysis. However, an imaging pattern-based approach may facilitate the diagnosis and optimal management of perirenal tumors and pseudotumors.

Clinical syndromes associated with ovarian neoplasms: A comprehensive review

Functional ovarian neoplasms have unique clinical manifestations related to hormone overproduction and may give rise to a broad spectrum of clinical syndromes. Sex cord-stromal tumors, the most common functional ovarian neoplasms, are associated with either hyperestrogenism (as in granulosa cell tumor and thecoma) or hyperandrogenism (as in Sertoli-Leydig cell tumor and Leydig cell tumor). Other, less common ovarian neoplasms that may have endocrine or nonendocrine syndromic manifestations include germ cell tumors associated with the excessive production of human chorionic gonadotropin (eg, choriocarcinoma, dysgerminoma), monodermal teratomas (eg, carcinoid tumor, struma ovarii) associated with carcinoid syndrome and hyperthyroidism, and primary epithelial ovarian cancers associated with paraneoplastic syndromes. The application of diagnostic algorithms based on patient demographic information, clinical manifestations, laboratory findings, and cross-sectional imaging features may help identify ovarian neoplasms in complex clinical settings.

Cross-sectional Imaging Evaluation of Renal Masses

Most renal masses are neoplastic in origin. Recent advances in cytogenetics and oncology continue to expand our knowledge of the genesis and biology of renal tumors with their attendant implications on patient management. Current state-of-the-art CT and MR imaging technology permit improved detection and better characterization of renal masses. Refinements in surgical techniques and the use of novel ablative technologies to treat patients who have renal masses allow optimal management, with reduced morbidity and mortality. Elucidation of specific oncologic pathways in renal cell carcinomas has led to the development of molecularly targeted therapies. The critical role of cross-sectional imaging techniques in the diagnosis, surveillance, and management of patients who have renal masses continues to expand.

Unusual imaging appearances of endometriosis

OBJECTIVE Endometriosis is defined as tissue resembling the endometrium occurring outside the uterus. The purpose of this article is to familiarize the radiologist with the wide spectrum of pelvic endometriosis and to review the distinctive imaging findings. Infrequent manifestations of endometriosis, including malignant degeneration, scar endometriosis, association with ascites, and invasive endometriosis, are described. CONCLUSION The manifestations of endometriosis commonly present a challenge to the gynecologist and radiologist. Familiarity with its varied presentations may allow accurate diagnosis.

Wunderlich syndrome: Cross-sectional imaging review

Wunderlich syndrome (WS) is a rare condition characterized by acute onset of spontaneous, nontraumatic renal hemorrhage into the subcapsular and perirenal spaces. Wunderlich syndrome is classically characterized by the Lenks triad: acute flank pain, flank mass, and hypovolemic shock. However, the clinical manifestations can be varied and nonspecific. A wide spectrum of neoplastic and nonneoplastic renal pathologies may result in WS. Renal neoplasms are the most common cause for WS, with angiomyolipoma being the most common benign neoplasm, whereas renal cell carcinoma is the most common malignant neoplasm. Other causative conditions of WS include vascular causes (vasculitis [polyarteritis nodosa being the most common cause], renal artery aneurysms, arteriovenous malformations and fistulas, and venous thrombosis), cystic renal diseases, renal infections, calculus disease, nephritis, and coagulation disorders. Cross-sectional imaging findings help in the detection of the subcapsular and/or perinephric hemorrhage and may identify underlying etiology. Renal angiography not only helps in diagnosis of the underlying cause in select cases but also allows control of active bleeding, which can avoid unnecessary emergent radical surgery.

Chronic fibrosing conditions in abdominal imaging

Chronic fibrosing conditions of the abdomen are relatively poorly understood and involve varied and often multiple organ systems. At histopathologic analysis, they share the unifying features of proliferative fibrosis and chronic inflammation. Different conditions in this group are often found in association with each other and with other fibrosing conditions outside the abdomen. Some of the confusion about these conditions stems from their complex nomenclature, which includes a gamut of alternate terms and eponyms. Many of them can be categorized within two large subgroups: the fibromatoses and immunoglobulin G4 (IgG4)-related disorders. While many of these entities are of uncertain etiology, some, especially the IgG4-associated conditions, appear to have an immune-mediated pathogenesis. Nephrogenic systemic fibrosis, sclerosing peritonitis, and retroperitoneal fibrosis have iatrogenic associations, while some of the fibromatoses are genetically inherited. Imaging differentiation of these conditions is difficult due to considerable overlap in their radiologic findings. However, certain conditions such as penile fibromatosis and sclerosing peritonitis may have unique imaging features that can help the radiologist make the diagnosis. Others such as deep fibromatoses and inflammatory pseudotumor demonstrate fibroproliferative mass formation and cannot be differentiated from neoplastic conditions at imaging. Thus, histopathologic correlation is often required to confirm their diagnosis.

Inflammatory Myofibroblastic Tumors: Current Update

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm of intermediate biological potential with a predilection for the lung and abdominopelvic region. IMT represents the neoplastic subset of the family of inflammatory pseudotumors, an umbrella term for spindle cell proliferations of uncertain histogenesis with a variable inflammatory component. IMTs show characteristic fasciitis-like, compact spindle cell and hypocellular fibrous histologic patterns and distinctive molecular features. Imaging findings reflect pathologic features and vary from an ill-defined, infiltrating lesion to a wellcircumscribed, soft tissue mass owing to variable inflammatory, stromal, and myofibroblastic components.