Pediatric-type nodal follicular lymphoma: an indolent clonal proliferation in children and adults with high proliferation index and no BCL2 rearrangement

Abstract

Pediatric follicular lymphoma (PFL) is a variant of follicular lymphoma (FL) presenting as localized lymphadenopathy in children. Unlike conventional adult FL, PFL typically does not recur or progress. Clear diagnostic criteria for PFL are lacking, and it is uncertain whether this indolent lymphoma is defined by age or may occur in adults. We analyzed 27 FL in patients < 40 years of age and found that all 21 cases that lacked a BCL2 gene abnormality (BCL2-N; P < .0001) and had > 30% Ki67 fraction (high proliferation index, HPI; P ‫؍‬ .0007) were stage I and did not progress or recur; in comparison, all 6 cases with BCL2 rearrangement and/or PI < 30% were stage III/IV, and 5 of 6 recurred or progressed. In a separate cohort of 58 adult FL (> 18 years of age), all

Follicular lymphoma in young adults: a clinicopathological and molecular study of 200 patients

“…In these cases, CD10 was negative in 37%; there was lack of BCL2 rearrangement in 89% and presence of BCL6 rearrangement in 35%. Unlike Louissaint et al, 9 who found all BCL2 rearrangement-negative/highprofoliferative index (BCL2-N/HPI) cases to be stage I among 58 adult follicular lymphoma studied (Z18 years of age), in our series, just onethird were stage I follicular lymphoma. Liu et al 8 found expression of MUM1/IRF4 in all pediatric follicular lymphoma cases involving the Waldeyer ring.…”

“…Recently, follicular lymphoma occurring in children was characterized in detail. 8,9 We undertook the current study on an extensive cohort of young adults between the ages of 19 and 40 years, because of the dearth of knowledge regarding the clinicopathologic features and the outcome in patients diagnosed with follicular lymphoma in that age group. Most follicular lymphoma cases in patients o40 years are manifested in the older age subgroups within this population (35-39 years) and are more common in female population.…”

“…It is typically localized, demonstrates specific clinical, morphologic, immunohistochemical, and genetic features, and confers a more favorable clinical outcome than its adult counterpart. 8,9 In contrast, the biologic behavior of follicular lymphoma in young adults, defined as 18-40 years of age, has not been well-studied. Follicular lymphoma in this age group represents 15-20% of all lymphoma diagnoses.…”

Early lymphoid lesions: conceptual, diagnostic and clinical challenges

“…However, BCL6 and MYC aberrations typically associated with aggressive B-cell lymphomas are absent. 57,58,61,62 Overlap with florid follicular hyperplasia remains a practical and theoretical problem, as most PTFL lack specific genetic aberrations, and whether some of these cases may represent limited clonal expansions in florid follicular hyperplasia is still a subject of debate. 63 Nodal PTFL is an indolent disease with a very good prognosis.…”

“…57,58 Known as the pediatric variant or pediatric type of FL (PTFL), it differs from the adult counterpart morphologically, immunophenotypically, and genetically. 59,60 It presents predominantly in young males, most often as isolated cervical lymphadenopathy.…”