Extranodal follicular dendritic cell sarcoma.

Extranodal follicular dendritic cell sarcoma is a rare tumor of follicular dendritic cells that can occur in a wide variety of sites. Although fairly well characterized histologically, with a distinct immunophenotype, it remains under-recognized, with as many as one third of cases initially misdiagnosed. This is often due to a failure to consider the entity.

Use of the ThinPrep method in bile duct brushings: analysis of morphologic parameters associated with malignancy and determination of interobserver reliability.

Recent work suggests the ThinPrep method can improve diagnostic sensitivity and accuracy in bile duct brushings. However, the proportion of atypical and suspicious diagnoses remains high. The aim of this study was to identify the most useful morphologic features in ThinPrep bile duct cytology and evaluate interobserver reliability.

Desmoplastic small round cell tumor: using FISH as an ancillary technique to support cytologic diagnosis in an unusual case.

Desmoplastic small round cell tumor is a rare and aggressive neoplasm that predominantly affects young males. In almost all cases, a reciprocal translocation is present resulting in the fusion of the Ewing sarcoma gene with the Wilms' tumor gene. Here we describe an unusual case occurring in a 59-year-old male, in which fluorescence in situ hybridization (FISH) was used in conjunction with immunohistochemical studies to confirm the diagnosis.

Silent corticotroph cell pituitary adenoma in a struma ovarii.

This is the first report of a silent corticotroph cell pituitary adenoma arising in a struma ovarii. The patient, a 79-year-old woman, was found to have an asymptomatic left-sided adnexal mass confirmed by vaginal sonography to be a complex cystic and solid tumor. Pathological analysis demonstrated an 8-cm partially cystic struma ovarii in which there was a focus of predominantly basophilic adenohypophyseal cells arranged in a diffuse pattern, adjacent to mature neural tissue containing numerous Herring bodies.

Ras1 controls pheromone expression and response during mating in Cryptococcus neoformans.

The Cryptococcus neoformans Ras1 signal transduction pathway controls mating, hyphal differentiation, and the ability of this opportunistic human fungal pathogen to grow at elevated temperatures. To further elucidate how Ras1 signals in this organism, the RAS1 gene was disrupted in the congenic serotype D strain background. Genetic epistasis experiments indicated that Ras1 regulates the mating response through the MAP kinase/pheromone response pathway.

Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans.

The Ras1 signal transduction pathway controls the ability of the pathogenic fungus Cryptococcus neoformans to grow at high temperatures and to mate. A second RAS gene was identified in this organism. RAS2 is expressed at a very low level compared to RAS1, and a ras2 mutation caused no alterations in vegetative growth rate, differentiation or virulence factor expression.