Claudete Esteves Klumb

Geographic variation in Epstein-Barr virus-associated Burkitt's lymphoma in children from Brazil

In developing countries, BL has a strong association with EBV infection during childhood. In South America, the data have shown an EBV association intermediate between that reported in the United States (30%) and that in equatorial Africa (95%). Early age at EBV infection and lower socioeconomic status have been related to increased EBV‐associated BL in developing countries. In Brazil, there are not enough data on childhood BL related to EBV infection. Our aim was to evaluate the clinicopathologic features and EBV association of 44 children with NHL from the state of Rio de Janeiro, situated in the southeast of Brazil. EBV was detected using RNA in situ hybridization in 36 biopsy specimens. DNA from fresh tumor samples and from paraffin‐embedded tissues of patients were analyzed by PCR, in which the first reaction included primers for an EBNA‐2 common region while the nested reaction amplified the region discriminating between EBV types 1 and 2 in separate reactions. EBV was detected in 21 of 29 BLs (72%), and type 1 virus infected the majority of EBV‐positive BLs (18/21). There was a trend for younger age in children with EBV‐positive BL compared to EBV‐negative BL (median age 4 compared to 6 years, respectively; p = 0.056). Our study confirmed that in the southeast of Brazil BL had an intermediate association with EBV. A higher rate of EBV‐associated BL was described in the northeast of Brazil. These differences are probably related to regional socioeconomic status. In conclusion, our study suggests that early infection with EBV in the background of a low socioeconomic condition associated with other environmental factors could contribute to BL in Brazil.

DNA sequence profile of TP53 gene mutations in childhood B‐cell non‐Hodgkin's lymphomas: prognostic implications

Objectives: The TP53 gene encodes a nuclear protein implicated in the regulation of the cell cycle, DNA repair, and apoptosis. TP53 mutations and other alterations have been described in numerous types of tumors, and some of these have been associated with poor prognosis. The aim of this study was to characterize TP53 mutations in childhood B non‐Hodgkins lymphoma, their correlation with clinical prognostic factors and response to therapy.

Coexpression of p53 protein and MDR functional phenotype in leukemias: the predominant association in chronic myeloid leukemia.

One of the best characterized resistance mechanisms of leukemias is multidrug resistance (MDR) mediated by P‐glycoprotein (Pgp) and multidrug‐resistant related protein (MRP). In addition to Pgp and MRP, p53 mutation or inactivation might play a relevant role in therapeutic failure. Some studies have demonstrated that Pgp and MRP may be activated in association with overexpression of mutant or inactivated p53 protein. The aim of this study was to investigate the association between p53 expression and MDR functional phenotype analyzed by flow cytometry (FCM).

Clinical and demographic characteristics of Epstein-Barr virus-associated childhood Burkitt’s lymphoma in Southeastern Brazil: epidemiological insights from an intermediate risk region

This report describes clinical and demographic characteristics of Epstein-Barr virus-associated childhood Burkitt’s lymphoma in Southeastern Brazil. We studied a group of 54 children with Burkitt’s lymphoma from Southeastern Brazil, where epidemiological status of Burkitt’s lymphoma is poorly understood. Epstein-Barr virus association showed an intermediate frequency (~60%) between endemic and sporadic subtypes. Median age was five years. Epstein-Barr virus infection was significantly associated to low age (Epstein-Barr virus+ four years vs. Epstein-Barr virus− eight years). Sex ratio (M:F) was 2:1, with a significantly higher number of males in old age classes. Young age at diagnosis and excess of males at older ages, as well as a causal relationship between low age, epstein-barr virus and Burkitt’s lymphoma risk, may characterize Burkitt’s lymphoma in Brazil.

Frequent expression of multiple myeloma 1/interferon regulatory factor 4 in Burkitt lymphoma

Burkitt lymphoma is a highly aggressive non-Hodgkin lymphoma with endemic, sporadic, and immunodeficiency-associated clinical variants composed of monomorphic medium-sized B cells with a high proliferation rate and a translocation involving the C-MYC locus. Classically, the immunophenotype of Burkitt lymphoma has been considered to be the germinal center type. In most reports, all cases of Burkitt lymphoma are reported to be multiple myeloma 1-negative. multiple myeloma 1 expression is seen in plasma cells and in a small fraction of B cells located in the light zone of germinal centers corresponding to the final step of intra-germinal center B-cell differentiation, and in activated T cells. Therefore, multiple myeloma 1 expression may denote the final step of intra-germinal center B-cell differentiation at the centrocyte stage, as well as the subsequent steps of B-cell maturation toward plasma cells. Unlike most normal germinal center B cells, in which the expression of multiple myeloma 1 and bcl-6 are mutually exclusive, the tumor cells in approximately 50% of multiple myeloma 1-positive DLBCL show coexpression of bcl-6, suggesting that the expression of these proteins may be deregulated. Twenty-five Burkitt lymphoma cases, including 19 associated with HIV, were reported in one of the few studies in the literature; 2 of these cases showed occasional multiple myeloma 1-positive cells, less than the 20% cutoff for positivity. We studied 222 cases of well-characterized Burkitt lymphoma with the classic phenotype and C-MYC translocation and found 90 cases (40.5%) with multiple myeloma 1 nuclear expression, suggesting a late germinal center stage of differentiation.

Pediatric lymphomas in Brazil

OBJECTIVE: This study provides the clinical pathological characteristics of 1301 cases of pediatric/adolescent lymphomas in patients from different geographic regions of Brazil. METHODS: A retrospective analyses of diagnosed pediatric lymphoma cases in a 10‐year period was performed. We believe that it represents the largest series of pediatric lymphomas presented from Brazil. RESULTS: Non‐Hodgkin lymphomas represented 68% of the cases, including those of precursor (36%) and mature (64%) cell origin. Mature cell lymphomas comprised 81% of the B‐cell phenotype and 19% of the T‐cell phenotype. Hodgkin lymphomas represented 32% of all cases, including 87% of the classical type and 13% of nodular lymphocyte predominant type. The geographic distribution showed 38.4% of the cases in the Southeast region, 28.7% in the Northeast, 16.1% in the South, 8.8% in the North, and 8% in the Central‐west region. The distribution by age groups was 15–18 years old, 33%; 11–14 years old, 26%; 6–10 years old, 24%; and 6 years old or younger, 17%. Among mature B‐cell lymphomas, most of the cases were Burkitt lymphomas (65%), followed by diffuse large B‐cell lymphomas (24%). In the mature T‐cell group, anaplastic large cell lymphoma, ALK‐positive was the most prevalent (57%), followed by peripheral T‐cell lymphoma, then not otherwise specified (25%). In the group of classic Hodgkin lymphomas, the main histological subtype was nodular sclerosis (76%). Nodular lymphocyte predominance occurred more frequently than in other series. CONCLUSION: Some of the results found in this study may reflect the heterogeneous socioeconomical status and environmental factors of the Brazilian population in different regions.

Rosai-Dorfman disease: a report of eight cases in a tertiary care center and a review of the literature

Rosai-Dorfman disease (RDD) is a nonmalignant histiocytic disorder of unknown origin that is extremely rare. By immunohistochemistry, the RDD cells are characteristically S-100 positive and CD1a negative. Emperipolesis is a common histopathological finding, although not specific for RDD. Lymph node and cutaneous manifestations are most frequent, but diverse organs can be affected. The clinical course is unpredictable regardless of treatment. Here, we present a series of 8 cases presenting lymph node and/or cutaneous lesions. Lymph node involvement was seen in diverse regions, including mediastinal and retroperitoneal. The treatment response to steroids was diversified, and the chemotherapy response was disappointing. Associated autoimmune diseases (Sjögren syndrome and antiphospholipid syndrome) were observed in 2 patients. Regardless of therapy modality, these patients exhibited a favorable prognosis in a follow-up duration that ranged from 15 to 80 months.

miR-17-92 cluster components analysis in Burkitt lymphoma: overexpression of miR-17 is associated with poor prognosis

Burkitt lymphoma (BL) is an aggressive B cell lymphoma characterized by the reciprocal translocation of the c-Myc gene with immunoglobulin genes. Recently, MYC has been shown to maintain the neoplastic state via the miR-17-92 microRNA cluster that suppresses chromatin regulatory genes and the apoptosis regulator Bim. However, the expression and prognostic impact of miR-17-92 members in pediatric BL (pBL) are unknown. Therefore, we investigated miR-17, miR-19a, miR-19b, miR-20, and miR-92a expression and prognostic impact in a series of 41 pBL samples. In addition, Bim protein expression was evaluated and compared to miR-17, miR-19a, miR-19b, miR-20, and miR-92a levels and patient outcomes. The expression of miR-17-92 members was evaluated by qPCR and Bim protein by immunohistochemistry. Log-rank test was employed to assess prognostic impact. We found that upregulated expression of miR-17 and miR-20a correlates with lack of pro-apoptotic Bim expression. Patients bearing tumors with upregulated miR-17 displayed decreased overall survival (OS), and multivariate analysis revealed that miR-17 was a significant predictor of shortened OS. Using hairpin inhibitors, we showed that inhibition of miR-17 resulted in enhanced Bim expression in a BL cell line overexpressing the miR-17-92 cluster. Our results describe for the first time miR-17, miR-19a, miR-19b, miR-20a, and miR-92a expression profiles in pBL. The prognostic impact of miR-17 should be validated in a larger series, and may provide new therapeutic avenues in the era of anti-miRNA therapy research. Additional functional studies are further required to understand the specific role of miR-17-92 cluster members in BL.

Circulating cell-free and Epstein–Barr virus DNA in pediatric B-non-Hodgkin lymphomas

Tumor-derived DNA is elevated in the plasma of patients with cancer. The analysis of circulating DNA may be useful for diagnosis, prognosis evaluation, and early detection of disease recurrence. In order to investigate cf-DNA as a marker during treatment, we serially quantified total cell-free (cf) and EBV plasma DNA in 30 cases of pediatric B-non-Hodgkin lymphoma by real-time PCR. The cf-DNA levels were significantly increased in patient samples at diagnosis as compared with the healthy controls (p < 0.001). At the end of treatment, a significant decrease in plasma DNA concentration was observed as compared with values observed at diagnosis (median: 94.0 copies/mL, p = 0.001). EBV was detected by ISH in 7/30 patients. Plasma EBV DNA levels were obtained from seven EBV-positive patients (median: 1278 copies/mL), while EBV DNA was not detected in 23 EBV-negative patients and 10 healthy controls. The association between the two methods of detection was statistically significant, with 100% correlation (Kappa coefficient, p = 1). In addition, the decrease of EBV viral load was associated with therapy response. Quantification of plasma EBV DNA may become a valuable source for disease detection of pediatric EBV-associated lymphomas and for monitoring treatment response.

Lymphoma subtype incidence rates in children and adolescents: first report from Brazil.

BACKGROUND Lymphoma is the third most common pediatric malignancy. The purpose of this study was to analyze the incidence rates of lymphoma in children and adolescents in Brazil. METHODS All cases of Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), and Burkitt lymphoma (BL) were extracted from 14 population-based cancer registries (PBCRs) from 2000 to 2005, and included children and adolescents 0-19 years old. Analyses included age-adjusted incidence rates (AAIRs) and age-specific incidence rates (ASIRs) by each PBCR. A social exclusion index (SEI) was built and used as proxy for socioeconomic status (SES) levels. Correlations between SES and incidence rates were investigated using Spearmans test. RESULTS The median incidence of lymphoma was 22.7/million. AAIRs of lymphomas varied from 12.9 (Salvador) to 34.5 per million (São Paulo). Median AAIR was 8.8/million, 9.8/million, and 2.9/million for NHL, HL, and BL, respectively. In all PBCRs except that of Recife, AAIR was slightly higher in males than females. The median ASIR was highest for HL (18.5/million) at 15-19 years for both genders. For NHL there were two peaks for ASIR: 11.1/million (1-4 years of age) and 13.2/million (15-19 years of age). The median ASIR for BL was highest among children aged 1-4 years (4.7/million) and in males. Higher SEI correlated with higher incidence of HL (P = 0.06), whereas rates of NHL and BL did not correlate with SEI. Borderline different incidence rates were observed in HL correlated with cities with higher SEIs. CONCLUSION Incidence rates of lymphomas in Brazil do not differ compared to rates reported worldwide, although SES differences deserve further investigation.