Epithelioid malignant peripheral nerve sheath tumors arising in pre-existing schwannomas are extremely rare. We report an unusual example occurring in a patient with multiple schwannomas (schwannomatosis), all but one of which showed “neuroblastoma-like” histology. By immunohistochemistry, both the epithelioid malignant peripheral nerve sheath tumor and the schwannomas showed a complete loss of the Smarcb1 protein. Subsequent genetic evaluation revealed the presence of a novel germline mutation in the SMARCB1/INI1 gene in the patient and three of her children, two of whom were diagnosed with atypical teratoid/rhabdoid tumors of the brain.
Mutational analysis of c-KIT or PDGFRA has become an important laboratory assay for patients with gastrointestinal stromal tumors (GISTs) because the results are useful in predicting the responsiveness to imatinib. To assess the diagnostic usefulness of denaturing high-pressure liquid chromatography (DHPLC) in this setting, we performed DHPLC and DNA sequencing to study exons 9, 11, 13, and 17 of c-KIT and exons 12 and 18 of PDGFRA in 54 consecutive cases of GIST collected from a single population. Most (40/54 [74%]) carried c-KIT mutations, and 7 (13%) carried PDGFRA mutations. These results were similar to those described in the literature. It is important to note that DHPLC was found to be highly sensitive, detecting all of the mutations in these 6 exons that were identified by DNA sequencing. Our data suggest that DHPLC is a cost-effective, rapid, and sensitive test for screening for mutations of c-KIT and PDGFRA in GISTs.
Histoplasma capsulatum is a dimorphic fungus endemic to North America. Histoplasmosis is primarily an inhalation-acquired mycosis that is encountered rarely outside of endemic regions. In nonendemic regions, histoplasmosis may present a diagnostic challenge and both clinical and laboratory vigilance are required to accurately identify infection. Unusual clinical presentations with limited physical findings may compound the difficulty in diagnosis. We describe a 78-year-old retired soil science professor who presented with an eroded epiglottic mass secondary to disseminated histoplasmosis in a nonendemic region (Alberta). Clinically, this mass was thought to represent a primary laryngeal carcinoma, as no other buccal or oropharyngeal ulcers were identified. Histoplasmosis was confirmed by tissue biopsy and a positive immunodiffusion test for immunoglobulin G. Disseminated histoplasmosis is often associated with laryngeal and oropharyngeal disease; however, isolated epiglottic histoplasmosis is rare. Histoplasmosis should be included in the differential diagnosis of neoplasms and chronic ulcers of the upper aerodigestive tract.
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