Large cell/anaplastic medulloblastomas and medullomyoblastomas: clinicopathological and genetic features.

OBJECT: Medulloblastoma is the most common malignant central nervous system neoplasm found in children. A distinct variant designated large cell/anaplastic (LC/A) medulloblastoma is characterized by frequent dissemination of cerebrospinal fluid (CSF) at presentation and a more aggressive clinical course. The authors report on their examination of the clinicopathological and genetic features of seven such cases encountered at their institution. METHODS: Eighty cases of medulloblastomas were reviewed and seven (8.8%) of these were believed to fit the histological and immunohistochemical criteria for LC/A medulloblastoma. In three cases (43%) either desmoplastic or classic medulloblastoma was the underlying subtype, and in two cases (28%) the LC/A tumor was found within the setting of medullomyoblastoma. Fluorescence in situ hybridization was used in six of the seven cases to characterize the presence of isochromosome 17q, deletion of chromosome 22q (a deletion characteristically found in atypical teratoid/rhabdoid tumors), and c-myc amplification. The patients' clinical histories revealed CSF dissemination in all cases and lymph node metastasis in one case. Isochromosome 17q was found in five (83%) of six cases. Evidence of chromosomal gains indicated aneuploidy in three tumors (50%), and amplification of c-myc was found in three tumors (50%). No 22q deletions were encountered. CONCLUSIONS: A high percentage of LC/A medulloblastomas arise within a background of typical medulloblastomas or medullomyoblastomas. As is the case in conventional medulloblastomas, the presence of 17q is a common early tumorigenic event; however, in a significant percentage of specimens there is also evidence of aneuploidy and/or amplification of c-myc. These findings indicate that LC/A morphological characteristics reflect a more advanced tumor stage than that found in pure medulloblastomas or in typical medullomyoblastomas.

A role for fluorescence in situ hybridization detection of chromosome 22q dosage in distinguishing atypical teratoid/rhabdoid tumors from medulloblastoma/central primitive neuroectodermal tumors.

It has been postulated that infants with medulloblastomas/central primitive neuroectodermal tumors (MB/PNET) may fare worse than older patients because some of them harbor unrecognized atypical teratoid/rhabdoid tumors (AT/RT), rare intracranial neoplasms that are typically unresponsive to therapy and rapidly fatal. Although small primitive cells are common to both entities, chromosome 22q11.2 deletions are common only in AT/RTs. Using fluorescence in situ hybridization (FISH) on archival, paraffin-embedded biopsy tissue with commercially available probes to 22q11.2, the region associated with RTs, we studied 8 cases of AT/RT, 12 cases of MB/PNET, and 4 cases of primitive central nervous system (CNS) neoplasms, which were difficult to classify. 22q Deletions were identified in 6 of 8 (75%) conventional AT/RTs and 0 of 12 (0%) children with classic MB/PNET. Of the 4 originally "difficult to classify" cases, 3 had deletions of 22q. In light of the FISH results, review of the morphology and immunophenotype resulted in 3 tumors being reclassified as AT/RTs and 1 as a large cell MB. These 4 cases highlight the potential diagnostic use of FISH for selected cases of primitive CNS malignancies in children and substantiate the notion that misdiagnosed AT/RTs may, in part account for the worse prognosis associated with "MB/PNET" in children younger than 2 years of age.

Schwannoma of the urinary bladder: a case report.

The urinary bladder is an extremely rare site for primary schwannomas. They are most often associated with von Recklinghausen disease. This patient was found to have a schwannoma of the bladder in the absence of evidence of von Recklinghausen disease and was successfully treated with a partial cystectomy. This represents only the third such case in the literature of this entity.

Unexpected recovery in a newborn with severe hypomyelinating neuropathy.

We report the case of a severely hypotonic and weak term newborn who required ventilatory support from the time of birth. Serial neurophysiologic studies were consistent with severe demyelinating polyneuropathy. The infant's condition deteriorated over several weeks despite treatment with corticosteroids and intravenous immunoglobulin (IVIG) for presumed inflammatory demyelinating polyneuropathy. Histopathologic findings in a sural nerve biopsy, however, were similar to those previously reported in congenital hypomyelinating neuropathies. After 12 weeks of hospitalization and after discontinuation of corticosteroids, the patient began to recover and required no further ventilatory support. Remarkable improvement has continued for 18 months. This patient raises questions about the underlying mechanisms of hypomyelinating neuropathies in early infancy.

A 63-year-old woman with right small finger pain.

The following case is presented to illustrate the clinical findings and imaging modalities of a condition of interest to the orthopedic/hand surgeon. The initial history, physical examination, and imaging examinations are found on this page. The final clinical and roentgenographic differential diagnosis and discussion can be found on the following pages.

Unexpected deaths due to colloid cysts of the third ventricle.

Colloid cysts of the third ventricle are rare central nervous system tumors that are a recognized cause of unexpected death in young, otherwise healthy adults and children. We report three adults and one child who died from colloid cysts of the third ventricle. Our report illustrates the difficulties of diagnosing these tumors premortem.

Cavernous sinus involvement in head and neck cancer.

Spread of tumor to intracranial structures is an infrequent and late manifestation of head and neck cancers. We recently encountered six patients with a distinct clinical syndrome due to involvement of the cavernous sinus, which forms the basis of this report. This syndrome was a source of significant morbidity and mortality, with a mean survival of only 4 months. The diagnosis is often elusive, but is now made more commonly than previously. Whether this reflects increased incidence (due to alterations in the natural history of disease by therapy) or improved diagnosis (due to modern imaging modalities) is unknown. Cavernous sinus involvement may be the first evidence of distant disease in head and neck cancer. Although survival is poor, palliation is worthwhile. Awareness of this syndrome can lead to earlier diagnosis and alteration of treatment.

Overexpression of sigma receptors in nonneural human tumors.

Previous data indicated that opioid receptors occur in both neural and nonneural human tumors. However, it has recently been shown that some of the putative opioid binding may be attributable to sigma sites. In this study the occurrence of sigma and opioid receptors in nonneural human tumors was assessed. The neoplasms included renal and colon carcinomas and a sarcoma. [3H]1,3-di-o-tolylguanidine was used to assay sigma receptors by homologous competition binding assays, which when analyzed provided dissociation constant and receptor density values. Opioid binding was measured with [3H]-(-)-ethylketocyclazocine, a ligand which interacts with mu, delta, and kappa subtypes. Fresh surgical specimens were obtained from 9 human neoplasms, selected for their large size, and compared with nonmalignant tissues. All 9 tumors contained sigma sites, and dissociation constant values were within the range of 27-83 nM. Occasionally, two-site fit the data better than one-site binding, suggesting the presence of multiple sigma sites. Opioid binding was not detected. Intratumoral variability was evaluated by sampling several locations on the periphery of the mass and one in the center. Each of the samples was bisected, with a portion reserved for histological examination to correlate morphological features with receptor data. Changes in sigma binding were not associated with the extent of fibrosis, viability, or necrosis. Receptor density values displayed moderate intra- and intertumoral variation (coefficients of variation, 8-39 and 27-49%, respectively). More important, sigma binding in tumors was found to be greater than or equal to 2-fold higher than that of control nonmalignant tissue.

Osmotic demyelination syndrome. Lack of pathologic and radiologic imaging correlation.

An otherwise healthy diabetic woman developed severe hyponatremia, her serum sodium ion levels were rapidly corrected to normal, and she had a course of improvement then neurologic deterioration, with seizures and coma developing in the subsequent two days. Imaging studies, including computed tomography and magnetic resonance images of the brain as late as 19 days after the osmotic insult, failed to show pathologically demonstrated demyelinating lesions. Osmotic brain injury induces demyelination in areas of gray-white apposition and, clinically, results in a delayed neurologic deterioration one to three days following the osmotic challenge. Even with magnetic resonance imaging, review of the literature and this experience suggest that osmotic demyelination cannot reliably be imaged during the first month after the insult.