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BackgroundPediatric follicular lymphoma has recently been recognized as a novel variant of follicular lymphoma in the World Health Organization classification of lymphomas. Given the rarity of the disease, histopathological and genetic data on this type of lymphoma are still scarce. Design and MethodsWe analyzed 25 cases of pediatric follicular lymphoma (patients aged ≤18 years) by morphology, immunohistochemistry and interphase fluorescence in situ hybridization. All patients analyzed were treated within Non-Hodgkin's Lymphoma -Berlin-FrankfurtMünster (NHL-BFM) multicenter trials, and the cohort was representative of the German population. ResultsThe genetic hallmark of adult follicular lymphoma, t(14;18)(q32;q21), was not detectable in any of the pediatric cases, although BCL2 protein was expressed in 55% of the latter cases. No correlation was found between BCL2 protein expression and outcome. Chromosomal breaks in the immunoglobulin heavy chain gene (IGH) and the BCL6 locus were detected in 5 of 17 and 1 of 18 cases, respectively. Patients with pediatric follicular lymphoma had long event-free survival and, in contrast to adult follicular lymphoma, the clinical course was not dominated by relapses. A simultaneous diffuse large B-cell lymphoma was frequently detected at initial diagnosis in children but did not indicate an aggressive clinical course. ConclusionsOur data suggest that pediatric follicular lymphoma is a disease that differs from its adult counterpart both genetically and clinically.Key words: pediatric follicular lymphoma, childhood lymphoma, pediatric diffuse large B-cell lymphoma, t(14;18). NonHodgkin's Lymphoma -Berlin-Frankfurt-Münster (NHL-BFM) multicenter trials. Haematologica. 2010; 95:253-259. doi:10.3324/haematol.2009 This is an open-access paper. Citation: Oschlies I, Salaverria I, Mahn F, Meinhardt A, Zimmermann M, Woessmann W, Burkhardt B, Gesk S, Krams M, Reiter A, Siebert R, and Klapper W. Pediatric follicular lymphoma -a clinico-pathological study of a population-based series of patients treated within thePediatric follicular lymphoma -a clinico-pathological study of a population-based series of patients treated within the Non-Hodgkin's Lymphoma -Berlin-FrankfurtMünster (NHL-BFM) multicenter trials

The causal role of human papillomaviruses (HPV) in squamous cell carcinogenesis of tonsillar cancers (TSCC) depends on the activity of the viral oncoproteins E6 and E7, leading to inactivation of the cellular tumor suppressor p53 and the retinoblastoma gene product pRb. Because of the negative feedback mechanisms, the pRb inactivation causes an increase of the inhibitor of the cyclin-dependent kinases p16 INK4a . In 39 TSCC specimens, genotyping based on the amplification of HPV DNA was carried out using PCR by applying HPV type-specific oligonucleotides. Subsequently, amplicons were hybridised with fluorescence-labeled complementary probes using the Southern blot technology. For HPV E6/E7 mRNA expression, Northern hybridization and RT-PCR were performed, and for p16 INK4a detection, immunohistochemistry was performed. With 21/39 (53%) HPV-positives, the detection rate is within the range that can be expected in TSCC. The E6/E7 oncogene mRNA was detectable in 11 cases, 10 of which showed positive signals after p16 INK4a staining. Albeit the small study group was investigated, the correlation of the HPV DNA status with the p16 INK4a expression was of statistical significance (p 5 0.02). Kaplan-Meier estimations revealed better survival outcome for patients with HPV-positive tumors with detectable E6/E7 mRNA and p16 INK4a overexpression (p 5 0.02, median observation time 29 months). As mRNA expression tests are not routinely available in many clinical diagnostic laboratories, and based on the high correlation of p16 INK4a staining with HPV E6/E7 mRNA expression, in conclusion we suggest for a deeper exploration for the use of p16 INK4a as a surrogate marker with the potential to impact the standard of care of HPV DNA-positive head and neck carcinomas.Malignant tumors of the upper aerodigestive tract account for $7% of all cancers worldwide, 1 with squamous cell carcinomas (SCCs) constituting the largest portion among the different tumor entities. 2 Even though a majority of SCCs of the head and neck (HNSCC) seems associated to etiologic factors as carcinogenetic substances in tobacco smoke and alcohol, 3 an increase of especially younger patients without reported misuse of these environmental factors in history has been recognized. 4 Therefore, an increase in knowledge of other factors such as the infection with human papillomaviruses (HPV) promoting carcinogenesis in especially the latter patient group gains in importance.Epidemiologic data demonstrate HPV DNA prevalences of about 20-30% concerning all anatomical tumor sites of the head and neck region, 4-6 with the SCC of the Waldeyer's tonsillar (squamous cell carcinogenesis of tonsillar cancers, TSCC) ring showing an HPV DNA-positive rate of up to 60% as particularly predestined for an infection with HPV. 4,5,7 Recent data from Sweden describe HPV DNA infections in tonsillar carcinomas in even up to 85% of the investigated patients. 8 HPV DNA-positive HNSCCs, again with accentuation of those derived from the Waldeyer's tonsillar ring, are considered as being ...