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 (