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Context.--Papillary thyroid carcinoma (PTC) is an uncommon tumor in the pediatric population. A limited number of studies have examined genetic mutations affecting the mitogen-activated protein kinase (MAPK) pathway in the pediatric population. Objective.--To examine mutations affecting this pathway in PTC in our pediatric population and compare the BRAF V600E mutation rates in pediatric and adult tumors. Design.--Eighty-four patients, including 14 pediatric and 70 adult, with PTC were tested for the BRAF V600E mutation by using real-time polymerase chain reaction and sequencing. Additionally, we examined the rate of RAS point mutations with real-time polymerase chain reaction and rearrangements of RET/PTC1 and RET/PTC3 in the pediatric group with fluorescence in situ hybridization. Clinical and histologic data were compared as well. Results.--Of 77 tumors that had an interpretable result, the BRAF V600E mutant was identified in 4 of 13 pediatric patients (31%) and 43 of 64 adult patients (67%), which was a significant difference (using Fisher exact test, P = .03). One pediatric and 6 adult cases did not reveal an interpretable result with melting curve analysis. One of these cases harbored a rare 3-base pair deletion mutation (c.1799_1801delTGA). Mutations in RAS genes were not seen in any pediatric tumors. One tumor with a RET/PTC1 rearrangement and another with RET/PTC3 were identified in the pediatric population (15%). Conclusions.--The rate of the BRAF V600E mutation in the pediatric population is significantly lower than that seen in the adult population. Mutations in RAS do not contribute significantly to pediatric PTC. This experience from our institution adds to the growing body of knowledge regarding tumor genetics in pediatric PTC. (Arch Pathol Lab Med. 2016; 140:134-139; doi: 10.5858/arpa.2014-0612-OA), Papillary thyroid carcinoma (PTC) is an uncommon tumor in the pediatric population. Despite having an excellent prognosis with long-term mortality rates of less than 1%, (1,2) pediatric patients with PTC [...]

Homologous recombination, a basic biological mechanism in Escherichia coli, involves 25 gene products which include RecA, RecBCD, ReCE, several exonoucleases, SSB proteins, DNA polymerases and DNA gyrases. These gene products exhibit strand exchange, DNA pairing, branch migration and several other recombination characteristics. Escherichia coli also possesses a cis-acting recombination hot-spot, chi, which is essential for regulatory function. Homologous recombination occurs in four different stages in Escherichia coli.

Context.--We reported previously that more than one-third (37%) of primary bladder squamous cell carcinomas (SCCs) demonstrate diffuse p16 immunoreactivity independent of gender. This observation made us question whether p16 overexpression in bladder carcinoma is due to human papillomavirus (HPV)-dependent mechanisms. Objective.--To determine whether the presence of high-risk HPV (HR-HPV) DNA could be detected in these tumor cells. Design.--Fourteen cases of primary bladder SCC, which were positive for p16 by immunohistochemistry, were probed for the detection of HR-HPV by in situ hybridization and the signal amplification Invader assay. Samples positive for detection of HR-HPV by Invader assay were amplified by using HR-HPV type-specific primers, and amplification products were DNA sequenced. Results.--Detection of HR-HPV by the in situ hybridization method was negative in all cases (0 of 14). However, in 3 of 14 cases (21.4%), the presence of HR-HPV DNA was detected with the Cervista HPV HR Invader assay, which was followed by identification of genotype. All positive cases were confirmed by using HR-HPV type-specific amplification followed by DNA sequencing. Identified HR-HPV genotypes included HPV 16 (2 cases) and HPV 35 (1 case). Conclusions.--High-risk HPV DNA is detectable in a subset of primary bladder SCCs. Based on the well-documented carcinogenic potential of HR-HPV, there is a necessity for additional studies to investigate the role of HR-HPV in bladder carcinogenesis. (Arch Pathol Lab Med. 2013;137:1088-1093; doi: 10.5858/arpa.2012-0122-OA), Bladder cancer is the second most common malignancy of the genitourinary tract diagnosed in the United States1 with approximately 70 000 newly diagnosed cases and 14 000 deaths from disease [...]