[1308] Pediatric Follicular Lymphoma: A Comparison with Follicular Lymphoma in Young Adults.

Qingyan Liu, Armin Jegalian, Mark Raffeld, Stefania Pittaluga, Elaine S Jaffe. NCI/NIH, Bethesda, MD

Background: Pediatric follicular lymphoma (PFL) is a recently recognized neoplasm of B-cell derivation, and differs from usual follicular lymphoma (UFL) which is associated with the t(14;18). Our study was intended to delineate the features of PFL and compare these lesions with UFL in a pediatric and young adult population to permit guidance in the definition and management of PFL.
Design: 63 FL cases (<29 year old) were collected from our institute's consult service and were graded according to the 2008 WHO classification. The demographic information, histologic features, and immunohistochemical (IHC) profile (CD20, CD3, CD10, Bcl-6, Bcl-2, IgD, CD21, and MUM1) of the cases were reviewed. PCR analysis of immunoglobulin gene rearrangement was performed.
Results: 23 of the 63 cases were grade 1-2 FL with a median age of 24 years (18-29 years) and a female predominance (M:F 1:2). These cases had histologic features and IHC profile similar to that of UFL. The remaining 40 cases were grade 3 FL (age range of 3-28 years), 28 of which were diagnosed as PFL. The PFL cases (24/28) were seen predominantly in male patients (M:F 7:1) with an age range of 3-18 years (median age 14), and located in Waldeyer's ring (7/24), testis (4/24), or lymph nodes (13/24). Interestingly, the remaining PFL (4/28) were seen in a young adult age group (19-28), all males, and were only seen in the lymph node. PFL displayed two main histologic features 1) effaced architecture by large expansile follicles (mainly in Waldeyer's ring) or 2) irregular or serpiginous follicles (mainly in lymph nodes). Both patterns showed a prominent starry sky in the follicles. The cases involving the testis showed interstitial atypical follicles similar to that described in the literature. The remaining grade 3 FL cases were in the young adult age group (19-28 years, median age 21) and exhibited histologic features similar to that of grade 3 UFL or had overlapping features with nodal marginal zone lymphoma. By IHC, all of the PFL cases were Bcl-6 positive and were usually Bcl-2 negative; the Waldeyer's ring cases were often diffusely MUM1+. 31/36 of the grade 3 FL cases (86%) were clonal for an immunoglobulin gene rearrangement by PCR.
Conclusions: PFL shows histologic features and an IHC profile that are distinct from its adult counterpart. PFL predominantly involves male pediatric patients but it may occasionally be seen in young adults. Diffuse MUM1 positivity may be a unique feature of PFL that involves the Waldeyer's ring.
Category: Hematopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 202, Wednesday Afternoon


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