Giant Juvenile Ectopic Schwannoma of the Temporal Bone.

BACKGROUND: Ectopic intracranial schwannomas (those that do not arise from a named cranial nerve) are rare. They account for <2% of surgically resected central nervous system schwannomas. CASE DESCRIPTION: We report the case of a 14-year-old boy presenting with a left conductive hearing loss and temporal bone deformity. No facial or cranial nerve deficits were present. Cross-sectional imaging demonstrated a large expansile extra-axial temporal bone mass, extending into and distorting the middle cranial fossa. At surgical resection the tumor was functionally and anatomically distinct from the facial nerve or any other identifiable neural structure within the middle ear or temporal bone. Histology confirmed a World Health Organization grade 1 schwannoma. CONCLUSIONS: This is the first reported case of a giant juvenile ectopic schwannoma within the temporal bone.

Malignancy in asymmetrical but otherwise normal palatine tonsils.

An abnormally large tonsil may be a sign of malignancy. We retrospectively analyzed the case files of 87 patients who had asymmetrically sized but otherwise normal tonsils and no risk factors for cancer to determine if asymmetry is associated with a higher incidence of malignancy. We found 2 cases (2.3%) of malignancy among these patients. One patient had high-grade non-Hodgkin's lymphoma in the larger tonsil, and the other had lymphocyte-rich Hodgkin's lymphoma. Both patients were older than 50 years, and neither had a history of recurrent tonsillitis. We believe that although the incidence of cancer in our series was small, it is significant. Therefore, we recommend routine excision of abnormally large tonsils. Moreover when making such a recommendation to a patient, it is essential that the patient have a clear understanding of the risk and benefit of having a tonsil removed solely because of asymmetry.

The presenting features of middle ear facial nerve sheath tumors: a clinical review.

Facial nerve sheath tumors are the most common middle ear benign neoplasms. Four facial nerve sheath tumors in the middle ear were diagnosed in our department over a 12-year period, and we described our experience in the management of these tumors. A thorough review of the English literature on middle ear peripheral nerve sheath tumors has been conducted, and the findings of this review are presented and discussed. We have paid particular attention to the presenting features of these tumors with the aim of enhancing diagnostic ability.

Single-walled carbon nanotube paper as a sorbent for organic vapor preconcentration.

Single-walled carbon nanotubes were examined as an adsorptive material for a thermally desorbed preconcentrator for organic vapors. The nanotubes were processed into a paper form and packed into a metal tube for flow-through sampling. Adsorbed vapors were released by a temperature-programmed desorption method and detected downstream with a flexural plate wave vapor sensor. The tested vapors, methyl ethyl ketone, toluene, and dimethyl methylphosphonate, were released from the packed column at different temperatures. The vapors were retained more strongly than previously observed for the widely used Tenax porous polymer, indicating a significant affinity of the single walled nanotubes for organic vapors.

Progressive thermal desorption of vapor mixtures from a preconcentrator with a porous metal foam internal architecture and variable thermal ramp rates.

A vapor preconcentrator has been designed with the porous polymer (Tenax) packed into a highly porous metal foam to facilitate thermal conductivity and temperature uniformity throughout the bed of the preconcentrator during heating. Vapors were desorbed using linear temperature programming from room temperature to a maximum temperature of 170 or 200 degrees C; the programmed duration of the thermal ramp was varied from 10 to 180 s. The partial separation of vapor mixtures that are thermally desorbed from the preconcentrator has been examined in terms of a metric for resolution, using methyl ethyl ketone, toluene, and dimethyl methylphosphonate as a test mixture. Vapors desorbed as a sequence of partially separated overlapping peaks, as observed with a polymer-coated flexural plate wave sensor. It was shown that vapor mixture resolution improved as the total time of the thermal ramp was extended from 30 to 120 s. In this way, the preconcentrator serves to act as a preseparator in addition to its usual functions for sampling, signal modulation, and improving sensitivity. Overlapping peaks were modeled, and peak areas were extracted using an exponentially modified Gaussian model. Peak areas were independent of the thermal ramp rate. Uses of such preconcentrators with multivariate detectors, such as sensor arrays, are discussed.