Reactive Lymphadenopathy in the Pediatric Population with a Focus on Potential Mimics of Lymphoma.

Benign lymphadenopathy is common in the pediatric population and may be clinically striking. As in adults, lymph node evaluation in pediatric patients requires careful morphologic and immunohistochemical assessment and clinical contextualization of the findings. It is important for the pathologist to be familiar with benign and reactive conditions that may mimic malignancy. This review presents non-neoplastic or indolent processes or patterns of lymphoid hyperplasia that may be confused with or raise the differential of lymphoma, with a focus on those more commonly encountered in the pediatric/adolescent population.

Morphologic and Immunophenotypic Differences in Juvenile Myelomonocytic Leukemias With CBL and Other Canonical RAS-pathway Gene Mutations: A Single Institutional Experience.

The diagnostic criteria for juvenile myelomonocytic leukemia have recently been revised to include clinical findings and RAS-pathway gene mutations per the 2016 World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues. Differing clinical behaviors have been observed in cases with CBL versus other RAS-pathway gene (RAS-p) mutations, notably the patients with CBL mutations can be self-limiting with spontaneous resolution. Additional clinical characteristics and histopathologic findings between these subsets are less well-described. We performed a retrospective search and identified cases with either CBL or RAS-p mutations, as per targeted and/or massively parallel sequencing. Eight patients had sufficient material for review, including cytogenetic studies and peripheral blood, bone marrow aspirate, and/or biopsy with flow cytometry analyses. Three patients showed CBL mutations and lower percentages of hemoglobin F and peripheral blood absolute monocyte counts, lesser degrees of leukocytosis compared with the RAS-p cohort, and normal megakaryocyte morphology and myeloblast immunophenotypes. Two of these patients were managed with observation only and experienced resolution of their disease. The patients with RAS-p mutations had severe thrombocytopenia, moderate to severe anemia, and experienced variable clinical outcomes. Abnormal megakaryocyte morphology and decreased numbers of megakaryocytes were seen in cases with RAS-p mutations. In addition, 3 of 4 cases with flow cytometry data demonstrated aberrant CD7 expression in myeloblasts. Our study is the first to identify morphologic and immunophenotypic differences between juvenile myelomonocytic leukemia cases with CBL or RAS-p mutations, and further supports previous reports of significantly different clinical behaviors between these subsets of patients.

Inv(11)(q21q23); KMT2A-MAML2, a Recurrent Genetic Abnormality in T-Cell Therapy-related Acute Lymphoblastic Leukemia.

T-cell therapy-related acute lymphoblastic leukemia (T-t-ALL) is a rare condition associated with previous cytotoxic therapy for another disease. Here we report T-t-ALL with inv(11)(q21q23), which involves KMT2A and MAML2, a transcriptional coactivator of NOTCH proteins, that occurred after chemotherapy for Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia. This case describes the youngest patient with T-t-ALL harboring inv(11)(q21q23) and is the first independent report following an initial series also occurring in children. Our results lend further support to the observation that the KMT2A-MAML2 fusion gene resulting from inv(11)(q21q23) is likely a recurrent cytogenetic abnormality in T-t-ALL and appears to be associated with pediatric cases.

Noninvasive encapsulated follicular variant of papillary thyroid carcinoma: Should it also be reclassified in children?

BACKGROUND: Noninvasive encapsulated follicular variant of papillary thyroid carcinoma (noniEFVPTC) has low risk of adverse outcome in adults, warranting reclassification as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). In children, thyroid nodules have higher risk of malignancy and it is unknown if encapsulated FVPTC (EFVPTC) and infiltrative FVPTC (IFVPTC) tumors have different behavior. We analyzed the clinicopathologic features of follicular variant of papillary thyroid carcinoma (FVPTC) subtypes in our pediatric population to determine if noniEFVPTC has an indolent course as reported in adults. PROCEDURE: We retrospectively studied all patients diagnosed with FVPTC at our institution. The clinicopathologic characteristics of the histologic subtypes were compared. RESULTS: Eighteen patients were identified, all treated with total thyroidectomy. No significant differences in age, sex, tumor size, focality, or prior malignancy were detected between subtypes. Extrathyroidal extension had significantly higher incidence in IFVPTC (5/8) compared with EFVPTC (1/10, P = 0.03), translating in significantly more T3 tumors within IFVPTC subtype (5/8), whereas most EFVPTC cases had T1 staging (6/10, T1 vs. T3, P = 0.05). EFVPTC had significantly lower rate of lymph node involvement (N1 in 2/8) compared with IFVPTC (N1 in 8/8, P = 0.003). Only one patient diagnosed with IFVPTC developed extranodal recurrence. When noniEFVPTC and iEFVPTC were separately compared, the noninvasive form showed no propensity for invasive growth (T3 staging: 0/4 vs. 2/6), lymph node metastasis (N1: 0/3 vs. 2/5) or extranodal recurrence. CONCLUSION: In children, noniEFVPTC/NIFTP has indolent behavior, warranting consideration of less aggressive management, similar to adults.

Higher antibody, but not cell-mediated, responses to vaccination in high physically fit elderly.

The purpose of this study was to examine whether cardiovascular fitness, independent of confounding factors, was associated with immune responsiveness to clinically relevant challenges in older adults (60-76 yr). Thirteen sedentary, low-fit (LF; maximal O(2) uptake = 21.1 +/- 1.1 ml.kg(-1).min(-1)) and 13 physically active, high-fit (HF; maximal O(2) uptake = 46.8 +/- 3.4 ml.kg(-1).min(-1)) older adults participated in this study. Dietary intake was assessed, and a battery of psychosocial tests was administered. In vivo antibody and ex vivo proliferative and cytokine responses to influenza (Fluzone) and tetanus toxoid (TT) vaccination and delayed-type hypersensitivity skin tests were performed. HF elderly individuals displayed a higher antibody response to two of the three strains included in the Fluzone vaccine as measured by hemagluttination inhibition, but there was no difference between groups in influenza-specific ex vivo proliferation or IFN-gamma or IL-10 production. HF elderly individuals exhibited a lower IgG(1) response and a tendency for a higher IgG(2) response to the TT vaccine. There were, however, no differences in TT-specific ex vivo proliferation or IFN-gamma or IL-10 production. In contrast, HF subjects had higher proliferative responses to phytohemagluttinin. In addition, there were no differences in delayed-type hypersensitivity responses to fungal antigens between groups. These results suggest that, after accounting for confounding factors, HF elderly individuals have higher antibody responses to Fluzone vaccine and a Th2 skewing of the antibody response to TT. There was little evidence that HF mounted better cell-mediated immune responses to the Fluzone or TT vaccine measured in peripheral blood cells or to other recall antigens in vivo.

Effects of a Taiji and Qigong intervention on the antibody response to influenza vaccine in older adults.

Previous studies have suggested that Taiji practice may improve immune function. This study was intended to examine whether 5 months of moderate Taiji and Qigong (TQ) practice could improve the immune response to influenza vaccine in older adults. Fifty older adults (mean age 77.2 +/- 1.3 years) participated in this study (TQ N = 27; wait-list control [CON] N = 23). Baseline pre-vaccine blood samples were collected. All subjects then received the 2003-2004 influenza vaccine during the first week of the intervention. Post-vaccine blood samples were collected 3, 6 and 20 weeks post-intervention for analysis of anti-influenza hemagglutination inhibition (HI) titers. We found a significant (p < 0.05) increase in the magnitude and duration of the antibody response to influenza vaccine in TQ participants when compared to CON. The vaccination resulted in a 173, 130, and 109% increase in HI titer at 3, 6, and 20 weeks post-vaccine, respectively, in the TQ group compared to 58, 54, and 10% in CON. There was a significant between group difference at 3 and 20 weeks post-vaccine and at 20 weeks the TQ group had significantly higher titers compared to the pre-vaccine time point, whereas the CON group did not. A higher percentage of TQ subjects also responded to the influenza A strains with a protective (> 40HI) antibody response (37% TQ vs. 20% CON for the H1N1 strain and 56% TQ vs. 45% CON for the H3N2 strain), but the differences between groups were not statistically significant. Traditional TQ practice improves the antibody response to influenza vaccine in older adults, but further study is needed to determine whether the enhanced response is sufficient to provide definitive protection from influenza infection.

Effects of a traditional Taiji/Qigong curriculum on older adults' immune response to influenza vaccine.

Previous studies have suggested that Taiji (T'ai Chi) practice may improve immune function. The current study examined whether 5 months of moderate traditional Taiji and Qigong (TQ) practice could improve the immune response to influenza vaccine in older adults. Fifty older adults participated in this study. Baseline pre-vaccine blood samples were collected. Subjects received the 2003-2004 influenza vaccine during the 1st week of the intervention. Post-vaccine blood samples were collected 3, 6 and 20 weeks after intervention for analysis of anti-influenza hemagglutination inhibition titers. Findings indicated a significant increase in the magnitude and duration of the antibody response to influenza vaccine in TQ participants when compared to controls. There was a significant between-group difference at 3 and 20 weeks after vaccine, and at 20 weeks the TQ group had significantly higher titers compared to the pre-vaccine time point, whereas the controls did not. A higher percentage of TQ subjects also responded to the influenza A strains with a protective antibody response, but differences between groups were not statistically significant. Traditional TQ practice improves the antibody response to influenza vaccine in older adults, but further study is needed to determine whether the enhanced response is sufficient to provide definitive protection from influenza infection.