Organisms identified in inflammatory lesions of eyes in the registry of ophthalmic pathology; Armed Forces Institute of Pathology, Washington, D. C.
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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.
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.
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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.
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.
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Many variants of papillary carcinoma of thyroid have been described. Identification of some of these may have prognostic implications. Eighty-two cases of papillary carcinoma of the thyroid diagnosed at Armed Forces Institute of Pathology, Rawalpindi over a six year period were reviewed with the aim of identifying these variants. Fifty-eight (70.7%) were classical papillary carcinoma. Thirteen (15.9%) had follicular variant, 6 (7.3%) columnar cell variant and 3 (3.7%) had tall cell variant. The mean age at diagnosis was 27 years for classical papillary carcinoma, 46 years for follicular variant, 61 years for columnar cell variant and 52 years for tall cell variant. The columnar cell variant had a more aggressive clinical presentation than others. Tall cell, columnar cell and diffuse sclerosing variant have a poor prognosis. An effort should be made to identify them on histopathology so that specific therapy can be planned.
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The Armed Forces Institute of Pathology uses telepathology and telemedicine programs to support its mission of providing pathology consultation, education, and research. The telepathology service is based on a static imaging or "store-and-forward" approach using both proprietary equipment and open systems through the Internet. Initiated in 1993, the service provides rapid expert consultation to pathologists globally. Diagnoses are provided by pathologists in 22 specialized departments. Educational programs are delivered through the World Wide Web. Category I continuing medical education credits can be obtained through Internet-based courses. Research activities are focused on forensic applications and the creation of image databases.
We reviewed the clinical records of 149 patients with pathologically proved cauda equina lesions in order to define the relative frequency and clinical presentations of the various diagnoses. The most common pathology was ependymomas (47 patients) followed in frequency by nerve sheath tumors (35 patients), metastases (27 patients), nonependymal glial neoplasms (six patients), meningiomas (six patients), lipomas (five patients), paragangliomas (five patients) and various other diagnoses (19 patients). Mean patient age at presentation for the various lesions included: metastases (51.5 years), nerve sheath tumors (49.7 years), nonependymal glial tumors (46.5 years), paragangliomas (41.2 years), ependymomas (38.3 years), meningiomas (34.7 years), and lipomas (18.4 years). ANOVA showed that the relationship between age and diagnosis for these groups to be statistically significant at a high level (P = 0.002). Low back pain was the most common symptom and occurred in 44 patients. Other symptoms included unilateral lower extremity pain or tenderness (24 patients), bilateral lower extremity pain or tenderness (16 patients), and bilateral lower extremity weakness (16 patients). No relationship between pathologic diagnosis and specific symptoms was found.
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The radiologic patterns caused by interstitial lung disease evoke a long list of differential diagnostic possibilities. Though the problem may at first seem insoluble, subdivision into conditions that spare the pulmonary architecture, as opposed to those that lead to an end-stage "honeycomb lung", and consideration of the clinical findings will frequently narrow down the list. Occasionally, key associated findings such as pleural effusion, pneumothorax, and systemic involvement of many organs will help rule out inappropriate diagnoses. Lymphangiomyomatosis is a rare cause of "honeycomb lung" that may result in a very specific combination of radiologic and clinical findings.