Malignant primary hepatic tumors in children include lesions unique to the pediatric age group and others that are more common in adults. Important considerations when evaluating a child with a liver tumor are the age of the patient, laboratory findings, and specific imaging features. The most common primary malignant hepatic tumor in the pediatric population, hepatoblastoma occurs almost exclusively in patients younger than 5 years with no history of liver disease. Hepatoblastoma is associated with elevated serum α-fetoprotein (AFP) level and appears predominantly solid. Hepatocellular carcinoma (HCC) is the most common malignant liver tumor in older children, often with a history of liver disease. HCC is associated with elevated serum AFP level and also appears as a solid mass. Fibrolamellar carcinoma occurs in adolescents without elevated AFP level and contains a T2-hypointense fibrous scar that usually does not enhance. Undifferentiated (embryonal) sarcoma occurs in young children, contains cystic and mucoid components, and mimics a cyst at magnetic resonance imaging and computed tomography but appears solid at ultrasonography. Epithelioid hemangioendothelioma is a multifocal vascular tumor in older children with a distinctive imaging appearance of confluent peripheral nodules with adjacent capsular retraction. Angiosarcoma rarely occurs in young children and frequently shows evidence of hemorrhage. Embryonal rhabdomyosarcoma of the biliary tree is unique to children, usually under 5 years of age, and frequently demonstrates an intraductal growth pattern. Knowledge of the pathologic features of these tumors and their imaging appearances can help radiologists offer an appropriate differential diagnosis and management plan.

Pancreatic endocrine tumors (PETs) are primarily well-differentiated tumors composed of cells that resemble normal islet cells but that arise from pancreatic ductal cells. They are classified as functioning or nonfunctioning according to their associated clinical symptoms; insulinoma, gastrinoma, and glucagonoma are the most common functioning PETs. They also are classified according to their biologic behavior, although all PETs have malignant potential. Most are sporadic, but some are associated with familial syndromes such as multiple endocrine neoplasia type 1, von Hippel-Lindau syndrome, and neurofibromatosis type 1. At imaging, PETs typically appear as well-defined hypervascular masses, a finding indicative of their rich capillary network. Cystic change, calcification, and necrosis are common in large tumors, which are associated with a poorer prognosis and a higher prevalence of local and vascular invasion and metastases than are smaller tumors. Even when metastases are present, many well-differentiated PETs have an indolent course. Poorly differentiated PETs are rare and have an infiltrative appearance; patients with such tumors have a poor prognosis. Knowledge of the characteristic clinical, pathologic, and radiologic features of PETs is important in the evaluation and management of patients with a suspected clinical syndrome or a pancreatic mass.

Male breast disease includes a variety of benign and malignant conditions, many of which are hormonally influenced. Gynecomastia and skin lesions account for the majority of conditions in symptomatic men with a palpable abnormality, and these conditions should be accurately recognized. Imaging patterns of gynecomastia include nodular, dendritic, and diffuse patterns. Histopathologically, the nodular and dendritic patterns correlate with the florid and quiescent (fibrotic) phases of gynecomastia, respectively. The diffuse pattern may have features of both phases and is associated with exposure to exogenous estrogen. Benign-appearing palpable masses in male patients should be approached cautiously, given the overlapping morphologic features of benign and malignant tumors. In addition to gynecomastia, other benign male breast tumors include lipoma, pseudoangiomatous stromal hyperplasia, granular cell tumor, fibromatosis, myofibroblastoma, schwannoma, and hemangioma. Male breast cancer accounts for 1% of all breast carcinomas. Invasive ductal carcinoma accounts for the majority of cases in adult males and typically appears as a subareolar mass without calcifications that is eccentric to the nipple. Other epithelial and mesenchymal tumors that may occur, albeit not as commonly as in women, include papillary carcinoma, invasive lobular carcinoma, adenoid cystic carcinoma, liposarcoma, dermatofibrosarcoma, pleomorphic hyalinizing angiectatic tumor, basal cell carcinoma of the nipple, hematopoietic malignancies, and secondary tumors. Knowledge of the natural history, clinical characteristics, and imaging features of tumors that occur in the male breast will help narrow the radiologic differential diagnosis and optimize treatment.

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Advanced imaging often reveals adrenal tumors and tumor-like conditions in both symptomatic and asymptomatic patients. When adrenal disease is clinically suspected, cross-sectional imaging can be helpful in evaluating the etiology of the patient's symptoms. When adrenal disease is incidentally identified, what the clinician and patient really want to know is whether the findings are benign or malignant, as this ultimately will affect their next step in management. Using radiologic-pathologic correlation, we broadly classify common, uncommon, and rare tumors and tumor-like conditions that can occur in the adrenal as benign or malignant. This classification follows predominant trends in observed biologic behavior while acknowledging those tumors that may behave in the minority in an unpredictable manner. We review the clinical background and presentation of functional adrenal tumors including Conn syndrome, Cushing syndrome, and catecholamine-secreting tumors, as well as their relationship with adrenal anatomy. We discuss a variety of benign tumors, including adrenal cortical adenoma (including oncocytoma) and pheochromocytoma, as well as uncommonly and rarely encountered tumors such as myelolipoma, hemangioma, lymphangioma, schwannoma, ganglioneuroma, and adenomatoid tumor. A variety of tumefactive but nonneoplastic lesions are addressed, including adrenal cortical hyperplasia, adrenal hemorrhage, adrenal cysts, and infections. Malignant tumors discussed include adrenal cortical carcinoma, the rare malignant pheochromocytoma, lymphoma, metastases, and sarcomas. For each tumor and tumor-like lesion, the clinical presentation, epidemiology, key imaging findings, diagnostic differential considerations, and management options are briefly addressed. Finally, an approach to the workup of suspected or incidentally discovered tumors is presented based on a selected literature survey and our clinical experience. Radiologists play an important role in identification and diagnosis of adrenal tumors and tumor-like conditions in both symptomatic and asymptomatic patients.

Vascular abnormalities of the breast include a wide spectrum of arterial and venous disorders, as well as benign and malignant vascular masses. Multimodality imaging is often necessary to accurately diagnose several of these uncommon conditions, and pathologic correlation can be important for accurate diagnosis of vascular masses. After a review of the vascular anatomy of the breast, the authors discuss the imaging appearance of several native arterial disorders (atherosclerosis and aneurysm) and venous disorders (superior vena cava syndrome, congestive heart failure, thrombophlebitis, and varix). Benign vascular tumors (hemangioma, lymphangioma, and angiolipoma) and malignant vascular tumors (angiosarcoma and hemangiopericytoma) that may be encountered in the breast are also reviewed. In addition, pitfalls in the correct interpretation of vascular breast lesions (devascularization of masses and pathologic mimics) are reviewed. Understanding and assessing normal and pathologic breast vasculature will permit more accurate diagnosis and treatment planning and allow breast imagers to have a more active role in breast care.

Sclerosing angiomatoid nodular transformation shows characteristic CT and MRI findings reflecting the underlying pathology. Typical features are a solitary, round, lobulated mass with early peripheral enhancing radiating lines and progressive enhancement of the angiomatous nodules; delayed enhancement of the fibrous tissue; and hypo-intense T2 signal intensity from hemosiderin deposition.

Both benign and malignant tumors and tumorlike conditions can arise from the nonepididymal extratesticular tissues. Benign tumors are far more common than malignant tumors, with lipoma being the most common lesion found at this site. Several imaging features can help narrow the differential diagnosis of these lesions, including the presence of fat and imaging features suggestive of fibrous tissue. Lesions that contain fat represent lipoma, liposarcoma, or angiomyofibroblastoma (AMF)-like tumor. If enhancing soft tissue is present in conjunction with fat, the differential diagnosis narrows further to just liposarcoma and AMF-like tumor. Lesions that display magnetic resonance imaging characteristics compatible with fibrous tissue are likely to be fibrous pseudotumor. However, many of the lesions in this location have overlapping imaging findings, and surgical excision is most often necessary for accurate diagnosis. The ability to narrow the differential diagnosis with imaging, however, is helpful for the clinician for both treatment planning and patient counseling.