Occult leptomeningeal large cell medulloblastoma in an adult.

OBJECTIVE AND IMPORTANCE: Large cell medulloblastoma is an uncommon malignancy of childhood that often pursues an aggressive clinical course. We report the first case of this entity in an adult that proved to be an unsuspected primary leptomeningeal tumor. CLINICAL PRESENTATION: A 30-year-old man complained of worsening neck pain over the course of 3 months. Neck pain increased a few days prior to admission and a cervical spine CT revealed tonsillar herniation. Cervical spine MRI performed the day prior to admission confirmed the diagnosis of Chiari I malformation and C3-4 disk herniation without spinal cord compression. On the day of admission, the patient became unresponsive and resuscitative measures were unsuccessful. Postmortem examination of the brain was notable for necrotic cerebellar tonsils, but demonstrated no evidence of an intraparenchymal mass lesion. Microscopic examination of the cerebellum revealed discohesive neoplastic cells, which showed characteristic dot-like immunoreactivity for synaptophysin, diagnostic of large cell medulloblastoma within the subarachnoid space. CONCLUSIONS: Our experience with this unique case illustrates the challenges of diagnosing a primary leptomeningeal neoplasm. This case also underscores the importance of maintaining a high degree of suspicion for leptomeningeal neoplasms in patients who present with imaging studies suspicious for Chiari I malformation.

Intracranial neurenteric cysts: imaging and pathology spectrum.

BACKGROUND AND PURPOSE: Intracranial neurenteric (NE) cysts are rare congenital lesions that may be mistaken for other, more common non-neoplastic cysts as well as cystic neoplasms. We delineate the imaging spectrum, pathologic findings, and differential diagnosis of NE cysts. METHODS: History, imaging, surgical and pathologic findings were analyzed retrospectively in 18 patients with intracranial NE cysts. Fifteen were surgically proved cases; 3 exhibited classic imaging findings and are being followed clinically. RESULTS: Thirteen cysts were located in the posterior fossa; 12 of 13 were extra-axial. Size varied from 1.2 x 0.8 x 0.6 cm to 3.4 x 3 x 2.5 cm. Five were supratentorial, measuring from 7 x 5 x 3 to 9 x 6 x 7 cm. All were frontal and off the midline. Seven of 18 patients had CT scans. Cysts varied widely in attenuation. None enhanced. Eighteen of 18 had MR images. Sixteen of 18 were hyperintense, and 2 were isointense to CSF on T1-weighted imaging. Sixteen of 18 were hyperintense on T2-weighted imaging. All cysts were hyperintense to CSF on fluid-attenuated inversion recovery (FLAIR) sequences. Diffusion imaging was performed on 2 patients. One case showed mild restriction. Mild posterior rim enhancement was seen in 5 cases at the site where the cyst adhered to brain parenchyma. CONCLUSION: The imaging spectrum for NE cysts is broader than previously reported. Intracranial NE cysts should be considered in the differential diagnosis for intracranial extra axial cystic lesions both above and below the tentorium.

Radiologic Anatomy Browser

It presents radiologic images (computerized tomography, arteriogram, lymphaniogram, upper gastrointestinal, Barium enema, and ultrasound) of the human body (head and neck, back and upper extremity, chest, abdomen, pelvis, and lower extremity).

Anatomy Browser's Glossary of Anatomical Terms

It presents definition for terms related to the human anatomy (from Abdominal aorta to Zygomatic arch), and a radiological image for each term.

The new WHO classification of brain tumors.

The current WHO classification greatly advances the ability to predict patient prognosis from pathologic diagnosis by introducing new tumor categories. This improved pathologic stratification is reflected in more accurate interpretations of diagnostic imaging studies. Pathology and oncology have progressed from a gross beginning, through microscopy and special stains, and into the realm of molecular biology and tumor genetics.

Clinical and imaging features of cervical chordoma.

OBJECTIVE: We attempted to define the clinical and imaging features of cervical spine chordoma. CONCLUSION: In this series of 10 patients, cervical spine chordomas tended to be large, multilevel destructive lesions of the midcervical region that caused pain and weakness in the neck and shoulder. Typically, these tumors primarily involved the vertebral body and extended into soft tissues of the perivertebral and epidural spaces. Surprisingly, almost a third of the tumors appeared on radiographs to predominantly occupy either the epidural or the intradural space, and nearly half resembled schwannomas. Although no imaging features were pathognomonic, CT and MR imaging were valuable in identifying the tumor, revealing its extent, and defining its relationship to the intraspinal structures.

Chemical shift: the artifact and clinical tool revisited.

The chemical shift phenomenon refers to the signal intensity alterations seen in magnetic resonance (MR) imaging that result from the inherent differences in the resonant frequencies of precessing protons. Chemical shift was first recognized as a misregistration artifact of image data. More recently, however, chemical shift has been recognized as a useful diagnostic tool. By exploiting inherent differences in resonant frequencies of lipid and water, fatty elements within tissue can be confirmed with dedicated chemical shift MR pulse sequences. Alternatively, the recognition of chemical shift on images obtained with standard MR pulse sequences may corroborate the diagnosis of lesions with substantial fatty elements. Chemical shift can aid in the diagnosis of lipid-containing lesions of the brain (lipoma, dermoid, and teratoma) or the body (adrenal adenoma, focal fat within the liver, and angiomyolipoma). In addition, chemical shift can be implemented to accentuate visceral margins (e.g., kidney and liver).

Congenital cystic masses of the neck: radiologic-pathologic correlation.

Cervical congenital cystic masses constitute an uncommon group of lesions usually diagnosed in infancy and childhood. The most common congenital neck mass is the thyroglossal duct cyst. The diagnosis is easily established from the presence of a cystic lesion in the anterior midline portion of the neck. The vast majority of branchial cleft cysts arise from the second branchial cleft. They can occur anywhere from the oropharyngeal tonsillar fossa to the supraclavicular region of the neck. Cystic hygroma is the most common form of lymphangioma. In the neck, cystic hygromas are most commonly found in the posterior cervical space. They typically extend into adjacent structures without respecting the fascial planes. Dermoid and epidermoid cysts result from sequestration of ectodermal tissue. The floor of the mouth is the most common location in the neck. Cervical thymic cysts are very uncommon lesions and are found anywhere from the angle of the mandible down to the sternum. Laryngoceles are classified into internal, external, and mixed types and have a frequent association with laryngeal carcinoma.

Orbital masses.

The "space approach" will be introduced as a means of analyzing orbital masses on imaging studies. Determination in which space an orbital mass resides, the character of its margin, the presence or absence of bony changes, and evidence of extension of the mass beyond the orbit often allows the radiologist to narrow the differential diagnosis and provides essential information to the ophthalmologist for definitive diagnosis and treatment planning.

The "dural tail sign": not always a meningioma.

Periorbital masses are often referred to oculoplastic surgeons. We report a 20-year-old patient presenting with a tender supertemporal mass that on gadolinium-enhanced magnetic resonance imaging (MRI) demonstrated a prominent dural enhancement adjacent to the mass, the so-called "dural tail sign." This sign has been reported to be highly specific for a meningioma; however recent literature challenges this view. In this case as well, the "dural tail sign" was not produced by a meningioma.

Cerebral MR imaging in intravascular lymphomatosis.

MR imaging data were reviewed retrospectively in four male patients (32 to 74 years old) with histologically confirmed intravascular lymphomatosis (IVL), a rare, aggressive form of non-Hodgkin lymphoma. MR findings included infarct-like lesions (n = 2), focal parenchymal enhancement (n = 3), dural/arachnoid enhancement (n = 2), and, in one case, nonspecific, patchy foci of increased signal in the white matter on long-TR images. All patients had multifocal lesions. Knowledge of the spectrum of MR imaging features in this unusual disorder may aid in diagnosis and potentially enhance the role of imaging in following response to therapy.

Primary central nervous system lymphoma: radiologic-pathologic correlation.

Once an extremely rare neoplasm, primary lymphoma of the central nervous system (CNS) now ranks behind only meningiomas and low-grade astrocytomas in prevalence. Understanding of primary CNS lymphoma has increased greatly in recent years as a result of special immunohistochemical stains. Virtually all primary CNS lymphomas are composed of B cells. Although a viral cause has been suggested in some cases, the exact cause of the disease is still under investigation. Primary CNS lymphoma has a distinct affinity for perivascular extension. Although granular nodules may be seen at gross pathologic inspection, diffuse microscopic spread is always present, which accounts for the ability of this tumor to produce distant disease and local recurrences. The dense cellularity of the tumor and its predilection for the periventricular region also explains its typical hyperattenuated appearance on unenhanced computed tomographic scans and hypointensity on T2-weighted magnetic resonance images. Virtually all lesions enhance with contrast material. Although the overall prognosis for patients with primary CNS lymphoma remains poor, some advances have been made with radiation therapy and chemotherapy for this once uniformly fatal disease.

Neuroimaging--autopsy correlations in AIDS.

This article is a brief review of the radiologic-pathologic correlation of central nervous lesions occurring in patients with AIDS. The major discussions of the imaging appearance and radiologic differential diagnosis have been presented elsewhere in this issue. Our emphasis is on the gross pathologic correlations that are only possible with autopsy materials. We will illustrate the opportunistic neoplasms such as primary CNS lymphoma. This article also discusses the imaging and pathology of the common opportunistic infections. Toxoplasmosis, an obligate intracellular protozoan, is the most common CNS infection producing a mass lesion in AIDS. However, AIDS encephalitis, a direct infection of the brain by the HIV-1 virus itself, may actually be more prevalent. Other viral infections occurring in AIDS include progressive multifocal leukoencephalopathy. Fungal diseases infecting the central nervous system of AIDS patients include cryptococcus, aspergillosis, and mucormycosis. The primary purpose of this article is to demonstrate how the gross pathology correlates with the radiologic images.

Papillary endolymphatic sac tumors: CT, MR imaging, and angiographic findings in 20 patients.

PURPOSE: To determine the computed tomographic (CT), magnetic resonance (MR) imaging, and angiographic findings of papillary endolymphatic sac tumors. MATERIALS AND METHODS: Clinical and imaging studies in 20 patients (aged 17-65 years) with histopathologically proved papillary endolymphatic sac tumors were retrospectively reviewed. Patients underwent CT (n = 18), MR imaging (n = 15), or angiography (n = 12). CT scans were evaluated for bone erosion and calcification; MR images, for signal intensity, enhancement patterns, and flow voids; and angiograms, for tumoral blood supply. RESULTS: All tumors were destructive and contained calcifications centered in the retrolabyrinthine region at CT. The MR imaging appearance varied with lesion size; 12 of 15 tumors showed increased signal intensity at T1-weighted imaging. The high-signal-intensity area was circumferential in lesions 3 cm or smaller and was scattered throughout the lesion in advanced tumors. Only tumors larger than 2 cm had flow voids. The blood supply arose predominantly from the external carotid artery. Large tumors had additional supply from the internal carotid and posterior circulation. CONCLUSION: Papillary endolymphatic sac tumors are destructive, hypervascular lesions that arise from the temporal bone retrolabyrinthine region. Increased signal intensity at unenhanced T1-weighted MR imaging is common and may help distinguish these lesions from more common, aggressive temporal bone tumors.

Disappearing enhancing brain lesion in a child with neurofibromatosis type I.

Neurofibromatosis type 1 (NF1) in children can produce a variety of parenchymal signal abnormalities on cranial MR. Areas of abnormal signal in these patients may represent regions of disordered myelination, "hamartomatous" change or frank neoplasia. The presence of contrast enhancement in intracranial lesions in patients with NF1 is usually strongly suggestive of tumor. We report the case of a child with NF1 and a focal enhancing brain parenchymal lesion which spontaneously resolved without specific therapy.

Lesions of the cauda equina: a clinical and pathology review from the Armed Forces Institute of Pathology.

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.

Botryomycosis ('bacterial ball') of the sinonasal tract caused by Pseudomonas aeruginosa.

BACKGROUND: Botryomycosis is a chronic bacterial infection that typically presents as a cutaneous lesion. Visceral involvement may occur, but mucosal disease is uncommon. We report two cases of sinonasal tract botryomycosis that clinically simulated a neoplasm. METHODS: Two cases of sinonasal tract botryomycosis were identified from the Otolaryngic Tumor Registry at the Armed Forces Institute of Pathology, Washington, DC. The clinical records, slides, and paraffin blocks were available for both cases. Histochemical stains, including Brown and Hopps, Gomori's methenamine-silver, acid-fast bacilli, mucicarmine, periodic acid-Schiff, and Warthin-Starry, were performed. RESULTS: The patients were an 81-year-old man and a 43-year-old woman. The man presented with acute ethmoiditis and a bulging eye. Radiographic studies showed a soft tissue mass in his left maxillary antrum with osseous erosion of adjacent anatomic sites. The woman presented with persistent headaches of more than 1 year's duration, with increasing severity in the months prior to presentation. An expansile soft tissue mass was identified in her right maxillary and ethmoid sinuses. Surgery was performed on both patients. The histology included amorphous, acellular material and separate, rounded eosinophilic granules associated with a neutrophilic infiltrate. A Splendore-Hoeppli phenomenon was seen. Filamentous gram-negative bacilli, identifiable only by histochemical staining, were morphologically compatible with Pseudomonas aeruginosa. Cultures of samples taken from both patients intraoperatively confirmed the organisms as P. aeruginosa. CONCLUSIONS: Sinonasal botryomycosis is a rare localized disease that may be mistaken clinically for an aggressive neoplasm. Complete surgical evacuation is curative.