Pediatric-type Follicular Lymphoma Research Articles

Pediatric-Type Follicular Lymphoma With A Prolonged Clinical Course And Unusual Mutational Profile

Abstract Casestudy: Pediatric-type follicular lymphoma is crucial to differentiate from other subtypes of follicular lymphomas since it carries an excellent prognosis and generally does not require radio- or chemotherapy. We present a 22-year-old male with an 8-year history of a left submandibular mass. Interval imaging studies showed no change in the mass size over time and no other sites of involvement. The patient underwent excision of the mass. Histologic sections showed effacement of nodal architecture with expansile follicles composed of medium sized to large lymphoid cells with blastoid features. Follicles showed abundant tingible body macrophages. Polarization was not seen. Neoplastic follicles were positive for CD20, PAX5, BCL6, CD10, and FOXP1, and negative for BCL2. PD1 positive cells were localized peripherally in the follicles. Clonality was confirmed by flow cytometry (kappa restricted CD10 positive B-cells in a polyclonal background) and by IGH PCR analysis (clonal peaks in FR1 and FR2). Molecular genetic testing showed the following mutations: TNFRSF14 W12* (VAF 14.8%), MAP2K1 F53V (5.7%), EZH2 Y646N (6.9%), ARID1A R1461* (7.1%). BCL2 rearrangement was not detected. MAP2K1 and TNFRSF1 are frequently reported in pediatric-type follicular lymphoma, however in the majority of cases they do not occur together. EZH2 mutation does not typically occur in pediatric-type follicular lymphoma, and is more common in classic adult- onset follicular lymphomas. Despite typical morphologic and clinical features, this patient showed a more complex genetic profile and EZH2 mutation, unusual findings in pediatric-type follicular lymphoma. It is conceivable that a higher genetic complexity has been acquired over time and is related to the long duration of the disease.

Clinicopathological characteristics of pediatric-type follicular lymphomas: an analysis of 37 cases

Objective: To study the clinicopathologic features, immunophenotype and prognosis of pediatric-type follicular lymphoma (PTFL). Methods: Thirty-seven cases of PTFL at the Beijing Friendship Hospital, Capital Medical University, from January 2012 to March 2018 were analyzed using light microscopy, immunohistochemistry, and polymerase chain reaction (PCR), and 13 cases were also examined using fluorescence in situ hybridization (FISH). Results: The male to female ratio was 35∶2. The median age was 16 years. Thirty-one patients were clinical stage Ⅰ and 6 were stage Ⅱ, displaying enlargement of lymph node in the head and neck regions. Follow-up information was available in 32 patients. Only two patients received low-dose chemotherapy, and none of these patients had relapse or disease progression at the latest follow-up (ranging from 16 to 79 months; median, 37 months). Morphologically, the lymph node architecture was partially or totally effaced by expansile follicles lacking polarization, with a prominent "starry sky" appearance. The cytologic composition was dominated by monotonous medium to large-sized blastoid cells with round to oval nuclei, finely clumped chromatin, small nucleoli, and scant cytoplasm. Immunophenotypically, all cases were positive for CD20, CD10, and bcl-6, but negative for bcl-2, MUM1 and C-MYC. Tumor cells were restricted to the follicles. The Ki-67 immunohistochemistry demonstrated a high proliferation (50% to 90%). Moreover, the tumor cells in the examined 28 cases were negative for CD43, CD5 and CD23. PCR analysis revealed monoclonal Ig gene rearrangements in all specimens. Thirteen cases being subjected to the FISH testing lacked bcl-2 and bcl-6 translocations. Conclusion: PTFL is different from conventional follicular lymphoma in their distinct morphology, immunophenotypic and molecular features, and behaves like an highly indolent or benign tumor.

Rare non-Hodgkin lymphoma of childhood and adolescence: A consensus diagnostic and therapeutic approach to pediatric-type follicular lymphoma, marginal zone lymphoma, and nonanaplastic peripheral T-cell lymphoma.

Pediatric-type follicular (PTFL), marginal zone (MZL), and peripheral T-cell lymphoma (PTCL) account each for <2% of childhood non-Hodgkin lymphoma. We present clinical and histopathological features of PTFL, MZL, and few subtypes of PTCL and provide treatment recommendations. For localized PTFL and MZL, watchful waiting after complete resection is the therapy of choice. For PTCL, therapy is subtype-dependent and ranges from a block-like anaplastic large cell lymphoma (ALCL)-derived and, alternatively, leukemia-derived therapy in PTCL not otherwise specified and subcutaneous panniculitis-like T-cell lymphoma to a block-like mature B-NHL-derived or, preferentially, ALCL-derived treatment followed by hematopoietic stem cell transplantation in first remission in hepatosplenic and angioimmunoblastic T-cell lymphoma.

Conjunctival Pediatric-Type Follicular Lymphoma.

Pediatric-type follicular lymphoma is an uncommon B-cell lymphoma that primarily involves the lymph nodes of the head and neck of children and young adults. Ocular involvement is rare, with only 5 well-documented cases in the literature, all occurring in the conjunctiva. The authors describe a 20-year-old African American man with enlarging bilateral medial conjunctival nodules. Excisional biopsy of the larger left conjunctival lesion, clinically presumed to be pyogenic granuloma, revealed pediatric-type follicular lymphoma composed of expansile follicles with germinal centers containing mitotically active blastoid cells, which coexpressed CD20, CD10, and BCL6 and lacked expression of BCL2. Polymerase chain reaction for immunoglobulin heavy chain rearrangement identified a monoclonal B-cell population. Fluorescence in situ hybridization studies failed to demonstrate BCL2, BCL6, and MALT1 gene rearrangements. Next-generation sequencing revealed a pathogenic MAP2K1 mutation, known to be enriched in pediatric-type follicular lymphoma. This report summarizes the clinical and pathologic diagnostic findings, biologic behavior, and management of conjunctival pediatric-type follicular lymphoma.

Novel markers in pediatric-type follicular lymphoma

The aim of this study was to review the histopathological, phenotypic, and molecular characteristics of pediatric-type follicular lymphoma (PTFL) and to assess the diagnostic value of novel immunohistochemical markers in distinguishing PTFL from follicular hyperplasia (FH). A total of 13 nodal PTFLs were investigated using immunohistochemistry, fluorescence in situ hybridization (FISH), and PCR and were compared with a further 20 reactive lymph nodes showing FH. Morphologically, PTFL cases exhibited a follicular growth pattern with irregular lymphoid follicles in which the germinal centers were composed of numerous blastoid cells showing a starry-sky appearance. Immunohistochemistry highlighted preserved CD10 (13/13) and BCL6 (13/13) staining, CD20 (13/13) positivity, a K light chain predominance (7/13), and partial BCL2 expression in 6/13 cases (using antibodies 124, E17, and SP66). The germinal center (GC)–associated markers stathmin and LLT-1 were positive in most of the cases (12/13 and 12/13, respectively). Interestingly, FOXP-1 was uniformly positive in PTFL (12/13 cases) in contrast to reactive GCs in FH, where only a few isolated positive cells were observed. FISH revealed no evidence of BCL2, BCL6, or MYC rearrangements in the examined cases. By PCR, clonal immunoglobulin gene rearrangements were detected in 100% of the tested PTFL cases. Our study confirmed the unique morphological and immunophenotypic features of PTFL and suggests that FOXP-1 can represent a novel useful diagnostic marker in the differential diagnosis between PTFL and FH.

Rare mature B‐cell lymphomas in children and adolescents

Pediatric-type follicular lymphoma (PTFL), pediatric nodal marginal zone lymphoma (pnMZL), and large B-cell lymphoma (LBCL) with IRF4 rearrangement have been introduced into the current World Health Organization (WHO) classification. They account for 5% to 10% of mature B-cell lymphomas in children and adolescents. Both PTFL and pnMZL predominantly affect male adolescents and usually present with localized lymphadenopathy in the head and neck region. The cells within the follicles of PTFL typically show high-grade cytology, IGH monoclonality and lack the t(14;18) chromosomal alteration. In contrast, pnMZL is characterized by progressive transformation of germinal center (PTGC)-like features and interfollicular proliferation of the cells with expansion of the marginal zones with diffuse areas. Watch and wait after complete resection seems an adequate therapy with chemotherapy restricted to incompletely resected disease. All children with PTFL and pnMZL reported, so far, survived. B-cell lymphomas presenting in the Waldeyer's ring are characterized by the expression of IRF4/MUM1 and often associated with IRF4 rearrangements. Because of the frequent diffuse component, treatment often follows current protocols for mature B-NHL. The prognosis is excellent.

Follicular lymphoma genomics.

Follicular lymphoma genomics.

Clinical observation of five pediatric-type follicular lymphoma in adult

目的探讨成人儿童型滤泡淋巴瘤（PTFL）患者的病理诊断、临床特征、治疗及转归特点。方法回顾性分析在江苏省人民医院就诊的5例成人PTFL患者的临床病理特点、实验室检查、诊治经过及随访结果，并结合文献进行综述。结果5例PTFL患者均为成年发病，中位年龄22（15~33）岁。起病时表现为局部无痛性淋巴结肿大，无发热、盗汗、消瘦等全身B症状。组织病理表现为典型的大滤泡结构，增殖指数高，存在免疫球蛋白重链基因克隆性重排，组化提示无BCL-2蛋白表达，荧光原位杂交未见BCL-2基因异常。所有患者均为Ⅰ~Ⅱ期，治疗仅通过局部肿块切除，未追加局部放疗或全身系统性免疫化疗。中位随访27个月，5例患者均处于持续缓解状态。结论成人PTFL病理增殖指数较高，无BCL-2表达和基因异常，临床多为局限病变，通过局部手术治疗预后较好，与经典成人滤泡淋巴瘤有显著差异。

The revised who classification of lymphomas – what has changed for the pathologist and clinician

The latest revision of the WHO classification reflects new insights gained over the preceding 8 years. The revision illuminates a broader spectrum of lesions at the very early stages of lymphomagenesis, providing guidance for diagnosis and management. These include monoclonal B-lymphocytosis, in situ follicular and mantle cell neoplasias, and pediatric type follicular lymphoma. Criteria have been developed for the distinction of lymphoplasmacytic lymphoma and marginal zone lymphoma, in part relying on identification of mutations in MYD88. There is a broader understanding of the genetic heterogeneity of DLBCL, and the distinction of the ABC and GCB subtypes. Moreover, aggressive B-cell lymphomas with double/triple hit involving BCL2, BCL6 and MYC are newly segregated from other DLBCL. In addition, newly recognised entities include IRF4-rearranged large B-cell lymphoma, with Burkitt-like lymphoma with 11q aberrations. Changes to the classification of T-cell lymphomas will be further clarified in a separate lecture.

A pediatric-type follicular lymphoma with marginal zone and monotypic intracytoplasmic plasmacytic differentiation

Pediatric-type follicular lymphoma and pediatric nodal marginal zone lymphoma are rare indolent lymphomas that are distinctive entities with excellent prognoses. We present the histopathology and the immunophenotypic, cytogenetic, and gene rearrangement findings of a unique, heretofore, unreported case of a 15-year old boy with a right-groin mass (5.5×4.5×3.5cm) with three discrete malignant components: 1) follicular lymphoma positive for CD20, CD10, and BCL6, but negative for BCL2; by flow cytometry, 9% of the cells were kappa monotypic B-cells that expressed CD10, CD19, CD20, and CD38; 2) typical marginal zone B-cell differentiation; marginal zone B-cells were positive for CD20, CD43, BCL2, and MUM-1, but CD10 and BCL6 negative. A small subset was weakly positive for intracytoplasmic IgM and kappa consistent with early plasmacytic differentiation; 3) Plasmacytoid forms, intracytoplasmic globules and crystals strongly expressed intracytoplasmic monotypic IgM and kappa.

Mutations of MAP2K1 are frequent in pediatric-type follicular lymphoma and result in ERK pathway activation

AbstractPediatric-type follicular lymphoma (PTFL) is a B-cell lymphoma with distinctive clinicopathological features. Recently, recurrent genetic alterations of potential importance for its pathogenesis that disrupt pathways associated with the germinal center reaction (TNFRSF14, IRF8), immune escape (TNFRSF14), and anti-apoptosis (MAP2K1) have been described. In an attempt to shed more light onto the pathogenesis of PTFL, an integrative analysis of these mutations was undertaken in a large cohort of 43 cases previously characterized by targeted next-generation sequencing and copy number array. Mutations in MAP2K1 were found in 49% (20/41) of the cases, second in frequency to TNFRSF14 alterations (22/41; 54%), and all together were present in 81% of the cases. Immunohistochemical analysis of the MAP2K1 downstream target extracellular signal-regulated kinase demonstrated its phosphorylation in the evaluable cases and revealed a good correlation with the allelic frequency of the MAP2K1 mutation. The IRF8 p.K66R mutation was present in 15% (6/39) of the cases and was concomitant with TNFRSF14 mutations in 4 cases. This hot spot seems to be highly characteristic for PTFL. In conclusion, TNFRSF14 and MAP2K1 mutations are the most frequent genetic alterations found in PTFL and occur independently in most cases, suggesting that both mutations might play an important role in PTFL lymphomagenesis.

Pediatric-type Follicular Lymphoma and Pediatric Nodal Marginal Zone Lymphoma: Recent Clinical, Morphologic, Immunophenotypic, and Genetic Insights.

Pediatric-type follicular lymphoma and pediatric nodal marginal zone lymphoma are 2 of the rarest B-cell lymphomas. Although they are both predominantly seen in children, they can manifest in the adult population as well. Our understanding of these lymphomas has advanced rapidly in recent years such that we not only have a firm grasp of the morphologic and immunophenotypic findings, but also have a deeper insight into critical genetic and molecular pathways of these diseases. This review will cover the clinical and pathologic characteristics, treatment, prognosis, and important differential diagnoses of these entities.

Diagnosis of Pediatric-Type Follicular Lymphoma in Young Adults (Own Data)

Aim. Pathomorphological, immunophenotypical and clinical characteristics of a new clinico-morphological form of pediatric-type follicular lymphoma (FL) in young adults discovered in 2008 (WHO classification). Background. FL is a heterogeneous disease according to its morphological, immunophenotypical and molecular-genetic characteristics. FL de novo includes transformed FL, FL without t(14;18), FL with diffuse growth associated with del(1p.36) and TNFRSF14 mutation. Pediatric-type FL in young adults is poorly studied; and it is especially interesting because of its clinical diversity and molecular-genetic heterogeneity of FL, in general. Methods. Biopsy materials taken from 5 patients (aged 18-25 years; median age: 22 years; the female/male ratio 3:2) were included in the study; all patients were examined, diagnosed and treated in the Hematology Research Center over the period from 2012 to 2016. Clinical stage I with isolated involvement a palatine tonsil or an inguinal lymph node was diagnosed in 4/5 patients; clinical stage II with involvement of a palatine tonsil and cervical lymph node was diagnosed in 1/5 patients. Morphological, immunophenotypical and FISH tests were performed with paraffin blocks. Results. The morphological pattern was typical for FL 3B (n = 2) and FL 3 with blastoid nucleus morphology (n = 3). Immunophenotypical features demonstrated an intermediate position between FL 3 de novo and transformed FL 3. No BCL-2 rearrangement was detected in any observation. Conclusion. The comparison of our data on characteristics of pediatric-type FL with those published in the literature demonstrated that lack or weak expression (&lt; 30 % of tumor substrate cells) of MUM1 was the key feature of the experimental group of young adults with pediatric-type FL. This, in turn, indicates the absence of IRF4 rearrangements and possible presence of other genetic abnormalities. The clinical, morphological, and immunophenotypical characteristics broaden the FL heterogeneity spectrum in young adults.

A study of the mutational landscape of pediatric-type follicular lymphoma and pediatric nodal marginal zone lymphoma

AbstractPediatric-type follicular lymphoma and pediatric marginal zone lymphoma are two of the rarest B-cell lymphomas. These lymphomas occur predominantly in the pediatric population and show features distinct from their more common counterparts in adults: adult-type follicular lymphoma and adult-type nodal marginal zone lymphoma. Here we report a detailed whole-exome deep sequencing analysis of a cohort of pediatric-type follicular lymphomas and pediatric marginal zone lymphomas. This analysis revealed a recurrent somatic variant encoding p.Lys66Arg in the transcription factor interferon regulatory factor 8 (IRF8) in 3 of 6 cases (50%) of pediatric-type follicular lymphoma. This specific point mutation was not detected in pediatric marginal zone lymphoma or in adult-type follicular lymphoma. Additional somatic point mutations in pediatric-type follicular lymphoma were observed in genes involved in transcription, intracellular signaling, and cell proliferation. In pediatric marginal zone lymphoma, no recurrent mutation was identified; however, somatic point mutations were observed in genes involved in cellular adhesion, cytokine regulatory elements, and cellular proliferation. A somatic variant in AMOTL1, a recurrently mutated gene in splenic marginal zone lymphoma, was also identified in a case of pediatric marginal zone lymphoma. The overall non-synonymous mutational burden was low in both pediatric-type follicular lymphoma and pediatric marginal zone lymphoma (4.6 mutations per exome). Altogether, these findings support a distinctive genetic basis for pediatric-type follicular lymphoma and pediatric marginal zone lymphoma when compared with adult subtypes and to one another. Moreover, identification of a recurrent point mutation in IRF8 provides insight into a potential driver mutation in the pathogenesis of pediatric-type follicular lymphoma with implications for novel diagnostic or therapeutic strategies.

Genome-wide analysis of pediatric-type follicular lymphoma reveals low genetic complexity and recurrent alterations of TNFRSF14 gene

AbstractPediatric-type follicular lymphoma (PTFL) is a variant of follicular lymphoma (FL) with distinctive clinicopathological features. Patients are predominantly young males presenting with localized lymphadenopathy; the tumor shows high-grade cytology and lacks both BCL2 expression and t(14;18) translocation. The genetic alterations involved in the pathogenesis of PTFL are unknown. Therefore, 42 PTFL (40 males and 2 females; mean age, 16 years; range, 5-31) were genetically characterized. For comparison, 11 cases of conventional t(14:18)− FL in adults were investigated. Morphologically, PTFL cases had follicular growth pattern without diffuse areas and characteristic immunophenotype. All cases showed monoclonal immunoglobulin (IG) rearrangement. PTFL displays low genomic complexity when compared with t(14;18)− FL (mean, 0.77 vs 9 copy number alterations per case; P < .001). Both groups presented 1p36 alterations including TNFRSF14, but copy-number neutral loss of heterozygosity (CNN-LOH) of this locus was more frequently observed in PTFL (40% vs 9%; P = .075). TNFRSF14 was the most frequently affected gene in PTFL (21 mutations and 2 deletions), identified in 54% of cases, followed by KMT2D mutations in 16%. Other histone-modifying genes were rarely affected. In contrast, t(14;18)− FL displayed a mutational profile similar to t(14;18)+ FL. In 8 PTFL cases (19%), no genetic alterations were identified beyond IG monoclonal rearrangement. The genetic landscape of PTFL suggests that TNFRSF14 mutations accompanied by CNN-LOH of the 1p36 locus in over 70% of mutated cases, as additional selection mechanism, might play a key role in the pathogenesis of this disease. The genetic profiles of PTFL and t(14;18)− FL in adults indicate that these are two different disorders.

Whole Exome Sequencing Defines the Genetic Differences Between Pediatric and Adult Follicular Lymphoma

Follicular lymphoma (FL) is the most common low grade lymphoma in adults, but uncommon in children. While the two diseases are similar in morphology and immunophenotype, pediatric-type FLs manifest higher grade histology with most cases being localized and curable with standard therapy. Pediatric-type FLs are thought arise from germinal center B cells and typically demonstrate higher expression of the germinal center B cell markers BCL6 and CD10.While the genetic basis of adult FL has been studied previously, the genetic basis of pediatric-type FL remains largely unknown. In this study, we sought to define the gene coding mutations occurring in pediatric FL and compared them to those of 48 adult FLs, as well as other adult lymphomas derived from germinal center B cells including 88 GCB DLBCLs and 67 cases of BL that we, and others, have published previously.We obtained a total of 32 pediatric-type FLs along with paired normal tissue. The median age wa 8 years with 62% male patients. We performed whole-exome sequencing for these cases using the Agilent solution-based system of exon capture, which uses RNA baits to target all protein coding genes (CCDS database), as well as ~700 human miRNAs from miRBase (v13). In all, we generated over 6 GB of sequencing data using high throughput sequencing on the Illumina platform.Using bioinformatics approaches that we have described previously, we identified 26 candidate cancer genes that were recurrently somatically mutated in pediatric FL. We found that the genes mutated in pediatric FLs were from three predominant ontologies/pathways. These included DNA damage repair (40%, ATM, RB1), chromatin modification (34%, SETD2, SMARCA4 and TET2) and alternative splicing (12%, SF3B1). We also noted IRF4 translocations and TNFRSF14 mutations in 10% of the cases as has been described previously.We further compared pediatric FLs to other germinal center B cell derived lymphomas and, in particular, FLs occurring in adults. We found that the mutations that characterize adult FLs including MLL2, CREBBP, and GNA13 were absent in pediatric FLs. There was only one pediatric FL case with an EZH2 mutation, which otherwise occur commonly in germinal center B cell derived lymphomas.Thus, pediatric FLs are genetically unlike both adult FLs and other germinal center B cell derived lymphomas. Our data provide new clues to the distinctive genetic basis of these tumors and their clinical behavior. DisclosuresNo relevant conflicts of interest to declare.

Indolent lymphomas in the pediatric population: follicular lymphoma, IRF4/MUM1+ lymphoma, nodal marginal zone lymphoma and chronic lymphocytic leukemia.

Indolent lymphomas in the pediatric population were discussed during the 2014 European Association for Haematopathology/Society of Hematopathology workshop in Istanbul, Turkey. This session was focused on pediatric-type follicular lymphoma (FL), and its differential diagnosis with the newly recognized entity of IRF4/MUM1+ lymphomas mainly involving Waldeyer's ring. The differential diagnosis between t(14;18) negative FL grade 1/2 and pediatric-type FL in adults was highlighted. The overlapping pathological and clinical features between FL and nodal marginal zone lymphoma (NMZL) in children and young adults were recognized and morphologic and immunophenotypical criteria helpful for the differential diagnosis were presented. Both pediatric-type FL and NMZL are indolent processes that should be distinguished from atypical lymphoid hyperplasia of the tonsils and lymph nodes. The demonstration of a B cell monoclonal population by molecular studies is strongly recommended for the diagnosis. Recognition of these indolent variants to avoid overtreatment was emphasized. Whereas most indolent lymphomas in the pediatric population show characteristic clinical, pathologic, and genetic features that differ from the adult counterpart, other rare indolent lymphoid tumors such as chronic lymphocytic leukemia (CLL) have similar characteristics. In this report, novel findings, areas of special interest, and diagnostic challenges emerging from the cases submitted to the workshop will be discussed.