Coexistence of Two Distinct Histological Subtypes of Follicular Lymphoma and Burkitt’s-Like Lymphoma in the Single Lymph Node: A Case Report and Literature Review.

Transformation to a high-grade lymphoma occurs in approximately 20% to 30% of cases of follicular lymphoma, usually to diffuse large B-cell lymphoma and small cases to Burkitt’s or Burkitt-like lymphoma, are reported. This transformation from follicular lymphoma to Burkitt’s lymphoma, namely the mechanism of the acquisition of c-MYC gene to tumor cells already immortalized by BCL2, are not completely understood. Case: A 49-year-old man visited our hospital because of high fever and generalized lymph node swelling for several weeks. The WBC count was 20x109/l including 60% of Burkitt-like blasts. Immunophenotype was positive for CD10, CD19 and CD20. FISH analysis with IGH/BCL2 probe set and sprit signal of 5′c-MYC /3′c-MYC showed positive for 79.3% and 3.9%, respectively. Needle biopsy of the bone marrow (BM) consisted of cells large non-cleaved lymphocytes arranged diffusely. Immunophenotype was positive for CD10, CD20, CD45LCA, CD79a, and strongly positive for MIB-1 by immunohistochemistry. FISH analysis of BM cells was performed as same way of peripheral blood (PB), and the result showed similar findings with peripheral blast cells. Excision biopsy of the neck lymph node showed effacement of architecture with the presence of 2 distinctive components in absolutory separated with each other. The first component consisted of follicles, some showing predominance of small-to medium-sized cells, termed centrocyte. The second consisted of large non-cleaved cells, known as centroblasts. The follicular lesion was positive for CD10, CD20, CD79a and BCL2 by immunohistochemistry. On the other hand, the diffuse component, the Burkitt-like lesion, was positive for CD10, p53 and strongly positive for MIB-1, but negative for CD20, CD79a and BCL2. The diagnosis was interpreted as a follicular lymphoma, grade 2, composite a Burkitt-like lymphoma in a diffuse pattern in the single lymph node. After he underwent 2 courses of chemotherapy, he relapsed in the cerebrospinal fluid. Inverted cells showed positive for CD10, CD19 but negative for CD20 and CD79a. FISH analysis of inverted cell was strongly positive for IGH/BCL2 and sprit signal of c-MYC, 98.8% and 98.5% respectively. Mukhopadhyay et al. reported the first case of the transformation of follicular lymphoma to Burkitt-like lymphoma within a single lymph node (Human Pathol. 2005, 36, 571). One study of transformed follicular lymphoma, 8% harbored c-MYC translocations (Blood 1992, 80, 756). We estimated that major gene expression was IGH/BCL2 with harbored c-MYC translocations in lymphoma cells and in a subset of follicular lymphoma, the gain of a c-MYC translocation confers an additive oncogenic stimulus and gain the inhibition of apoptosis by BCL2 combined with the cell growth activity by c-MYC.