Double-Hit and Triple-Hit Follicular Lymphoma.

Objectives: To better characterize the clinicopathologic presentation and outcomes of follicular lymphoma with MYC and BCL2 and/or BCL6 rearrangements (double-hit and triple-hit follicular lymphoma), we present three cases from our institution and perform a literature review of 37 published cases. Methods: Cases were identified using institutional SoftPath software and the MEDLINE database via the PubMed search engine. Clinical and pathologic data were collected with subsequent stratification by histologic grade and treatment for comparison. Results: Similar to classic follicular lymphoma, patients presented most often with low-grade (1-2) but high-stage (III-IV) disease with absence of B symptoms; however, overall survival was worse than that of traditional follicular lymphoma. In a small sample size, etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (EPOCH-R) achieved better outcomes than a regimen of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Specific pathologic features that might prompt testing for MYC rearrangement include elevated proliferation index out of proportion to cytology and aggressive features such as angioinvasion. Conclusions: Double-hit and triple-hit follicular lymphoma may be better classified as a distinct entity from classical follicular lymphoma with a worse prognosis. Aggressive therapy with a treatment regimen used for high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements might be beneficial, but more evidence is needed to justify aggressive treatment as standard of care.