From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation.

Numerous neurogenic tumors can affect the musculoskeletal system, including traumatic neuroma, Morton neuroma, neural fibrolipoma, nerve sheath ganglion, neurilemoma, neurofibroma, and malignant peripheral nerve sheath tumors (PNSTs). The diagnosis of neurogenic tumors can be suggested from their imaging appearances, including lesion shape and intrinsic imaging characteristics. It is also important to establish lesion location along a typical nerve distribution (eg, plantar digital nerve in Morton neuroma, median nerve in neural fibrolipoma, large nerve trunk in benign and malignant PNSTs). Traumatic and Morton neuromas are commonly related to an amputation stump or are located in the intermetatarsal space, respectively. Neural fibrolipomas show fat interspersed between nerve fascicles and are often associated with macrodactyly. Nerve sheath ganglion has a cystic appearance and commonly occurs about the knee. Radiologic characteristics of neurilemoma, neurofibroma, and malignant PNST at computed tomography (CT), ultrasonography, and magnetic resonance imaging include fusiform shape, identification of entering and exiting nerve, low attenuation at CT, target sign, fascicular sign, split-fat sign, and associated muscle atrophy. Although differentiation of neurilemoma from neurofibroma and of benign from malignant PNST is problematic, recognition of the radiologic appearances of neurogenic tumors often allows prospective diagnosis and improves clinical management of patients.     

From the archives of the AFIP. Benign tumors and tumorlike lesions of the gallbladder and extrahepatic bile ducts: radiologic-pathologic correlation. Armed Forces Institute of Pathology.

A diverse spectrum of benign tumors and tumorlike lesions arises from the gallbladder and bile ducts, and despite their diversity, these lesions share common embryologic origins and histologic characteristics. Although these lesions are relatively uncommon, their importance lies in their ability to mimic malignant lesions in these locations. Benign neoplasms are derived from the epithelial and nonepithelial structures that compose the normal gallbladder and bile ducts. The epithelium gives rise to adenomas, cystadenomas, and the unusual condition of biliary papillomatosis. Granular cell tumors, neurofibromas, ganglioneuromas, paragangliomas, and leiomyomas are examples of benign tumors that may originate from nonepithelial structures. Tumorlike lesions are more commonly found in the gallbladder and include xanthogranulomatous cholecystitis, adenomyomatous hyperplasia, cholesterol polyps, and heterotopias. In the clinical setting of a patient with nonspecific abdominal complaints or symptoms of biliary obstruction, the discovery of a gallbladder or bile duct polyp or mass, gallbladder wall thickening, or biliary stricture is most often indicative of malignancy. However, the differential diagnosis should include benign tumors and tumorlike lesions. The preoperative determination of a benign lesion may significantly alter therapy and patient prognosis.     

From the archives of the AFIP. Malignant germ cell tumors of the ovary: radiologic-pathologic correlation

Malignant germ cell tumors are the most common malignant ovarian neoplasms in girls and young women. The most well known of these neoplasms are dysgerminoma, immature teratoma, endodermal sinus tumor, and a mixture of two or more of these elements. All malignant germ cell tumors, especially immature teratoma, can be associated with mature (benign) teratoma. These tumors are generally large and have a complex but predominantly solid appearance on cross-sectional images. Elevated serum alpha-fetoprotein and human chorionic gonadotropin levels can help establish the diagnosis. Cystic areas of calcifications suggestive of mature teratoma do not exclude a co-existing malignant neoplasm.     

From the archives of the AFIP. Gestational trophoblastic disease: radiologic-pathologic correlation.

Gestational trophoblastic disease (GTD) is a manifestation of an aberrant fertilization event that leads to a proliferative process and, potentially, to an invasive neoplasm. The spectrum of GTD includes hydatidiform moles (complete and partial), invasive mole, choriocarcinoma, and placental site trophoblastic disease (rare). Increased levels of human chorionic gonadotropin (beta-hCG) are associated with all forms. Ultrasonography (US), performed late in the first trimester of a pregnancy complicated by hyperemesis gravidarum, toxemia, or bleeding, is essential in the early detection of hydatidiform mole, the most common form of GTD (80% of cases). In these cases, US typically reveals a central heterogeneous mass with anechoic spaces, which correspond to hydropic villi. In cases of invasive mole, imaging may show a central uterine process (similar to that seen in noninvasive moles), occasionally with myometrial invasion. Choriocarcinoma is often seen as a mass enlarging the uterus, with a heterogeneity that correlates with necrosis and hemorrhage. Because of the widespread availability of serum measurement of beta-hCG, diagnosis of the more severe, persistent manifestations of GTD seldom depends on radiologic examinations. However, imaging studies may alert the referring physician to the diagnosis in cases of early disease. Also, imaging studies may have a problem-solving role in examining patients with recurrent GTD or a confusing clinical picture.     

From the archives of the AFIP: extratesticular scrotal masses: radiologic-pathologic correlation.

The extratesticular scrotal contents consist of the epididymis, spermatic cord, and fascia derived from the embryologic descent of the testis through the abdominal wall. As opposed to intratesticular masses, most extratesticular masses are benign. Cystic masses (including hydroceles, epididymal cysts, and varicoceles) are easily diagnosed with ultrasonography (US) and are benign. Epididymitis is a common extratesticular lesion as well as the most frequent cause of an acute scrotum. It may be either acute or chronic and can be potentially complicated by epididymo-orchitis or scrotal abscess. Findings include epididymal enlargement, skin thickening, hydroceles, and hyperemia. The epididymis can also be affected by sarcoidosis, a noninfectious granulomatous disorder. The most common extratesticular neoplasms are lipomas (most often arising from the spermatic cord) and adenomatoid tumors (most often found in the epididymis). Despite their relative rarity, malignant neoplasms do occur and include rhabdomyosarcoma, liposarcoma, leiomyosarcoma, malignant fibrous histiocytoma, mesothelioma, and lymphoma. These tumors are often large at the time of presentation. The US findings of solid masses are often nonspecific. Magnetic resonance imaging can be very helpful in the evaluation of some of these disorders, allowing for a more specific diagnosis in cases of lipoma, fibrous pseudotumor, and polyorchidism. Copyright RSNA, 2003.     

From the archives of the AFIP. Cerebral intraventricular neoplasms: radiologic-pathologic correlation.

Intraventricular neoplasms are readily seen on cross-sectional images, but the myriad possibilities may make a focused differential diagnosis elusive. Consideration of the tissue within and composing the ventricular lining and the clinical findings provide the means to limit the differential diagnosis when analyzing an intraventricular mass on an imaging study. Ependymomas are typically calcified, are more common in children, are more common in the fourth ventricle, and show intense enhancement on contrast-enhanced images. Subependymomas and central neurocytomas have an affinity for the anterior portion of the lateral ventricle, and both commonly demonstrate a heterogeneous cystic appearance on cross-sectional images. Subependymomas are more common in older adults, whereas central neurocytomas are more common before 40 years of age. Subependymal giant cell astrocytomas always lie near the foramen of Monro and are characterized by frequent calcification, intense enhancement on contrast-enhanced studies, and the presence of other stigmata seen in tuberous sclerosis. When a mass is centered on the choroid plexus, a highly vascular tumor-either choroid plexus papilloma, choroid plexus carcinoma, meningioma, or metastasis-should be suspected. The characteristic heavily lobulated appearance of a choroid plexus tumor favors this diagnosis over other possibilities, although it is not always possible to distinguish between the more common benign form, the choroid plexus papilloma, and the less common malignant counterpart, the choroid plexus carcinoma. By using clinical, demographic, and imaging findings, one can significantly limit the differential diagnosis for many of the most common intraventricular neoplasms.     

From the archives of the AFIP. Infiltrative renal lesions: radiologic-pathologic correlation. Armed Forces Institute of Pathology.

Most renal masses exhibit an expansile growth pattern characterized by radial tumor enlargement that displaces normal renal parenchyma and forms spherical, often exophytic, lesions. These expansile masses have pushing margins that impress adjacent normal renal parenchyma but do not infiltrate it; this behavior results in a well-defined, encapsulated appearance at both radiologic and gross pathologic examination. In contrast, certain disease processes involve the kidney in an infiltrative fashion by using the normal renal architecture as scaffolding for interstitial growth. These infiltrative renal lesions lack a sharp border of demarcation with the normal parenchyma and therefore demonstrate ill-defined zones of transition between the lesion and normal parenchyma. Although infiltrative lesions frequently enlarge the kidney, its reniform shape is usually maintained. Cross-sectional imaging can often help distinguish infiltrative from expansile growth patterns through analysis of the parenchymal interface between the process and the kidney, the effect of the lesion on the collecting system and renal sinus, and the overall renal morphology. A wide variety of neoplastic and inflammatory conditions characteristically involve the kidney by cellular infiltration. Although considerable overlap of the imaging features exists among the various infiltrative processes, the correct diagnosis may be suspected when the clinical data and associated radiologic findings are considered together.     

From the archives of the AFIP. Leiomyosarcoma of the retroperitoneum and inferior vena cava: radiologic-pathologic correlation.

Leiomyosarcoma is the second most common primary retroperitoneal tumor in adults. Retroperitoneal leiomyosarcoma exhibits three major growth patterns: (a) completely extravascular (extraluminal) (62% of cases), (b) completely intravascular (intraluminal) (5% of cases), and (c) extra- and intraluminal (33% of cases). The usual clinical manifestation is a large abdominal mass. Intraluminal leiomyosarcoma may be accompanied by symptoms referable to venous thrombosis. The variable gross features and potential for intravascular extension result in various radiologic appearances, the most common being a large, partially necrotic soft-tissue mass in the retroperitoneum with or without extension into the inferior vena cava. Computed tomography and magnetic resonance imaging typically show a nonfatty, necrotic retroperitoneal mass and a vascular component when it is present. Ultrasound and angiography may also be useful, especially if vascular involvement is suspected from other imaging studies. Treatment of choice is surgical excision, which is frequently impossible due to the invasiveness of the tumor. Prognosis is related to extent of invasion and the adequacy of resection. Long-term prognosis is poor, and most patients die of local recurrence or distant metastasis.     

From the archives of the AFIP: superficial gliomas: radiologic-pathologic correlation. Armed Forces Institute of Pathology.

Glial neoplasms that are peripherally located and involve the cortical gray matter are noteworthy because of their predilection to serve as a seizure locus, their amenability to surgical resection, their generally favorable prognosis, and their characteristic imaging features, which facilitate diagnosis before surgery. The smaller lesions include ganglioglioma and dysembryoplastic neuroepithelial tumor. Gangliogliomas contain both neuronal and glial components and occur most commonly in the temporal lobe. Variant forms of gangliogliomas may occur and are related to the different compositions of the underlying cellular population. Gangliocytomas lack glial cells and are located both in the cerebral hemispheres and the cerebellum. Lhermitte-Duclos disease represents a specific type of cerebellar gangliocytoma with dysplastic features and is characterized by a laminar pattern at imaging. Dysembryoplastic neuroepithelial tumors occur predominantly in children and young adults with partial seizures and most commonly arise in the temporal lobe, frequently in combination with cortical dysplasia. Surrounding vasogenic edema is conspicuously absent in both gangliogliomas and dysembryoplastic neuroepithelial tumors. The larger masses in this group include desmoplastic infantile ganglioglioma and pleomorphic xanthoastrocytoma and tend to involve the leptomeninges and cortical territory. Both invoke an intense desmoplastic reaction, which appears as an enhancing soft-tissue component at imaging.     

From the archives of the AFIP. Mediastinal germ cell tumors: radiologic and pathologic correlation.

Germ cell tumors occur most frequently in the gonad but can rarely occur in extragonadal locations, usually in or near the midline. The most common extragonadal site of primary germ cell tumors is the anterior mediastinum. The most common histologic type of mediastinal germ cell tumor is mature teratoma, which is typically asymptomatic and incidentally discovered. Radiographically, these tumors appear as rounded, often lobulated masses; calcification may be seen. Imaging studies of mature teratoma frequently demonstrate cystic components and may demonstrate fat or calcium. Malignant germ cell tumors usually occur as large masses in symptomatic young male patients. Seminomas are typically of homogeneous soft-tissue attenuation, and nonseminomatous malignant germ cell tumors are typically of heterogeneous attenuation on computed tomographic scans. Therapy varies according to cell type and may include surgery, radiation therapy, or chemotherapy. Prognosis is excellent for patients with mature teratoma, good for patients with pure seminoma, and poor for patients with nonseminomatous malignant germ cell tumors and mixed germ cell tumors.     

From the archives of the AFIP. Paragangliomas of the head and neck: radiologic-pathologic correlation. Armed Forces Institute of Pathology.

Paragangliomas of the head and neck are ubiquitous in their distribution, originating from the paraganglia or glomus cells within the carotid body, vagal nerve, middle ear, jugular foramen, and numerous other locations. The typical patient is middle-aged and presents late in the course of the disease, with a painless slow-growing mass. Clinical manifestations include hoarseness of voice, lower cranial nerve palsies, pulsatile tinnitus, and other neuro-otologic symptoms. The overall prognosis of patients with a cervical paraganglioma is favorable, whereas its temporal bone counterpart often results in recurrence, residual tumor, and neurovascular compromise when in the advanced stage. Pathologic examination reveals a characteristic biphenotypic cell line, composed of chief cells and sustentacular cells with a peripheral fibrovascular stromal layer that are organized into a whorled pattern ("zellballen"). Imaging hallmarks of paragangliomas of the head and neck include an enhancing soft-tissue mass in the carotid space, jugular foramen, or tympanic cavity at computed tomography; a salt-and-pepper appearance at standard spin-echo magnetic resonance imaging; and an intense blush at angiography. Imaging studies depict the location and extent of tumor involvement, help determine the surgical approach, and help predict operative morbidity and mortality. Surgical treatment is definitive. Radiation treatment is included as a palliative adjunct for the exceptional paraganglioma not amenable to surgery.     

From the archives of AFIP. Imaging of giant cell tumor and giant cell reparative granuloma of bone: radiologic-pathologic correlation.

The radiologic features of giant cell tumor (GCT) and giant cell reparative granuloma (GCRG) of bone often strongly suggest the diagnosis and reflect their pathologic appearance. At radiography, GCT often demonstrates a metaepiphyseal location with extension to subchondral bone. GCRG has a similar appearance but most commonly affects the mandible, maxilla, hands, or feet. Computed tomography and magnetic resonance (MR) imaging are helpful in staging lesions, particularly in delineating soft-tissue extension. Cystic (secondary aneurysmal bone cyst) components are reported in 14% of GCTs. However, biopsy must be directed at the solid regions, which harbor diagnostic tissue. These solid components demonstrate low to intermediate signal intensity at T2-weighted MR imaging, a feature that can be helpful in diagnosis. Multiple GCTs, although rare, do occur and may be associated with Paget disease. Malignant GCT accounts for 5%-10% of all GCTs and is usually secondary to previous irradiation of benign GCT. Treatment of GCT usually consists of surgical resection. Recurrence is seen in 2%-25% of cases, and imaging is vital for early detection. Recognition of the spectrum of radiologic appearances of GCT and GCRG is important in allowing prospective diagnosis, guiding therapy, and facilitating early detection of recurrence.     

Unusual gastric tumors: radiologic-pathologic correlation.

The overlap of radiologic findings in many gastric tumors makes differentiation difficult. However, some unusual gastric tumors have characteristic radiologic features that may suggest a specific diagnosis. At barium study, lipomas typically manifest as a smooth submucosal mass or an ulcerated lesion with a "bull's-eye" appearance that is indistinguishable from other mesenchymal tumors. At computed tomography (CT), lipomas usually manifest as well-circumscribed submucosal masses with fat attenuation. At radiology, glomus tumors appear as smooth submucosal masses with or without ulceration and may contain tiny flecks of calcification. These tumors frequently demonstrate strong enhancement on early-phase contrast material-enhanced images. At barium study, lymphangiomas may appear as smooth intramural masses that are indistinguishable from other mesenchymal tumors. At CT, they manifest as non-enhancing extramucosal masses with homogeneous low attenuation. Diffuse lesions in Brunner gland hamartoma manifest as multiple small nodules, producing a characteristic "cobblestone" appearance. Lymphomas may have typical imaging features (eg, more pronounced and homogeneous mural thickening) that can help differentiate them from adenocarcinoma. In addition, adenocarcinomas may demonstrate unusual findings such as transpyloric spread, unusually large polyps, or intratumoral calcifications. Familiarity with these radiologic features of gastric tumors can help ensure correct diagnosis and proper management.     

From the archives of the AFIP. Giant cell tumor of the upper extremity

Giant cell tumor (GCT) is a relatively common primary bone tumor that typically develops in young adults between the ages of 20 and 40 years. Our archives contain 1,183 cases of histologically proved and radiographically correlated GCTs, collected in consultation over 40 years. From this large series, we identified 243 lesions (21% of GCTs) arising in the upper extremity distal to the scapula. This report demonstrates the spectrum of radiologic findings of GCT of the upper extremity, augmented where appropriate by accompanying pathologic material.     

From the archives of the AFIP: Localized fibrous tumor of the pleura

Eighty-two localized fibrous tumors of the pleura (LFTP) were reviewed retrospectively for the clinical, pathologic, and radiologic findings. Forty-four women and 38 men ranged in age from 17 to 78 years (mean, 54.7 years). Sixty-four benign LFTP ranged in size from 2 to 30 cm (mean, 13.2 cm), and 18 malignant tumors ranged from 3 to 23 cm (mean, 14.4 cm). Forty-eight patients (60%) presented with symptoms. Radiographs of 76 patients demonstrated solitary masses occupying or extending into the inferior hemithorax (79%). Computed tomography (CT) of 78 lesions demonstrated lobular masses (83%) that formed at least one acute angle (96%) or only acute angles (65%) with the adjacent pleura. Heterogeneous lesion attenuation was documented in 88% of enhanced and in 68% of unenhanced CT scans. Contrast enhancement was common (62% of cases). Magnetic resonance (MR) imaging of 18 lesions demonstrated heterogeneous signal intensity on both T1- and T2-weighted images (78% and 83%, respectively). Multiplanar MR imaging allowed visualization of the diaphragm and documentation of an intrathoracic mass in all cases. LFTP are solitary lobular heterogeneous masses that occur in symptomatic adults and often affect the inferior hemithorax. Malignant lesions are radiologically indistinguishable from those with benign histologic characteristics. Radiographic and CT features characteristic of pleural location are typically absent.