Clinical, Biological Characteristics and Outcome of Pediatric Follicular Lymphoma at Children's Cancer Hospital - Egypt: A Single Center Experience

Background: Pediatric follicular lymphoma is a rare entity that had been provisionally included in the WHO classification of hematologic malignancies. Unlike adults, pediatric follicular lymphoma patients usually presents with localized nodal disease, are translocation (14; 18) and BCL2 negative. It shows different clinical behavior and thus distinct outcome. We analyzed the three pediatric follicular lymphoma cases presented to Children's Cancer Hospital- Egypt (CCH-E) during the period from July 2007 to December 2014.

Results: All patients presented with localized stage II disease, responded well to R-CHOP chemotherapy (Rituximab target therapy with conventional CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone). One of them received involved field radiotherapy in addition. All patients are in continuous complete remission. The first case: A male patient 7 years old who presented with left upper deep cervical lymph node with B symptoms (fever and night sweets). Biopsy was taken, partial effacement of the nodal structure and obliteration of the sub-capsular sinus by confluent follicles, intermediate and large cells were seen microscopically. Immunohistochemical staining showed positivity to CD20 and BCL6 and negative reaction to CD3 and BCL2. MIB-1 index was high (80%). The diagnosis of diffuse large cell B-cell lymphoma in 40% of cells and pediatric follicular lymphoma grade 3a in the remaining 60% was made. The patient received 8 cycles of R-CHOP and placed under follow up from July 2011 till now.He is in complete remission. The second case: A male patient 8 years old who presented in March 2013 with recurrent right pre-auricular lymph node. Repeated biopsies were done, all revealed atypical lymphoid hyperplasia. The patient was placed under follow up till April 2014 when he presented with large right parotid mass from which another biopsy was taken. Microscopic examination revealed effaced nodal architecture by evenly distributed large uniform, crowded follicles & nodules, populated by centroblasts intermixed with centrocytes consistent with grade 3a follicular lymphoma. Some foci displayed diffuse pattern with evident extra nodal extension. Immunohstochemical staining showed positive reaction to CD20 and BCL6 while negative reaction to BCL2 and low expression of Ki-67. The diagnosis of pediatric follicular NHL, predominantly grade 3a was made. He received 6 cycles of R-CHOP, evaluation post 3rd cycle was in complete remission by CT and PET scan He completed 6 courses of R-CHOP followed by involved field radiotherapy. He is under follow up since April 2015 till now ; alive and in complete remission. The third case is also for a male patient 12 years old who presented with left parotid and bilateral cervical lymph node enlargement. Initial PET-CT was negative. Cervical lymph node biopsy showed partial effacement of lymph node architecture with observed vague follicular pattern as well as diffuse infiltrate dominantly composed of centroblastic neoplastic lymphoid cells admixed with centrocytes . Immunohostochemical staining revealed positive reaction to CD20 in the neoplastic large cells. BCL2 highlighted mainly the neoplastic cells mainly of diffuse pattern. BCL6 and CD10 highlighted the deformity of neoplastic follicles by growth of neoplastic cells. CD21 stained admixed follicular dendritic cells. Ki-67 labeling index was high (60%). The diagnosis of follicular NHL, mixed follicular and diffuse, grade 3 a was made. He received 6 cycles of R-CHOP, was in complete remission post the third cycle by CT evaluation and is currently under follow up since March 2015.

In conclusion, pediatric follicular lymphoma patients presented to our center had localized disease, responded well to R-CHOP chemotherapy and had durable complete remission.