Table 2. Major Histopathological Categories of Non-Hodgkin Lymphoma in Children and Adolescentsa continued...
Pediatric follicular lymphoma is a disease that differs from the adult counterpart genetically and clinically. The genetic hallmark of adult follicular lymphoma, the translocation of t(14;18)(q32;q21) involving BCL2, is typically not detectable in pediatric follicular lymphoma.[50,51,52] Molecular alterations observed in pediatric follicular lymphoma include translocations of the immunoglobulin locus and IRF4, losses of regions of chromosome 1p, and mutations of TNFSFR14 on chromosome 1p.[32,53]
Pediatric follicular lymphoma predominantly occurs in males, is associated with a high proliferation rate, is more likely to be localized disease, and has an EFS of approximately 94%. In contrast, adult follicular lymphoma usually presents as disseminated disease with a relatively low proliferation rate.[50,51,55] Cervical lymph nodes and tonsils are common sites, but disease has also occurred in extranodal sites such as the testis, kidney, gastrointestinal tract, and parotid.[50,51,52,55,56,57] The outcome of pediatric follicular lymphoma is excellent, and in contrast to adult follicular lymphoma, the clinical course is not dominated by relapses.[50,52,55,56] One study suggested that for children with stage I disease who had a complete resection, a "watch and wait" approach without chemotherapy may be indicated. Patients with higher-stage disease also had a favorable outcome with low- and intermediate-intensity chemotherapy with 94% EFS and 100% OS, with a 2-year median follow-up. It appears that BCL2-rearrangement negativity and high proliferative index predict favorable disease. In pediatric follicular lymphoma, a high-grade component (i.e., grade 3) resembling diffuse large B-cell lymphoma can frequently be detected at initial diagnosis but does not indicate a more aggressive clinical course in children.[50,52,55]
Other diseases appear to reflect the disease observed in adult patients. For example, MALT lymphomas observed in pediatric patients usually present as low-stage (stage I or II) disease, and pediatric gastric MALT lymphomas are associated with Helicobacter pylori and require no more than local therapy involving curative surgery and/or radiation therapy. Conjunctival MALT lymphomas are often associated with chlamydial psittaci infections. Intralesional interferon-alpha for conjunctival MALT lymphoma has been described.