Concurrent TP53 Mutation and Deletion in Refractory Low-grade Follicular Lymphoma

• Follicular lymphoma (FL) of low histologic grade (grade 1-2) is considered to be a clinically indolent disease. However, patients with FL can present in a heterogeneous manner and exhibit variably clinical behavior, and this heterogeneity is associated with underlying molecular and cytogenetic changes. • Understanding the prognostic factors of patients with FL early in the disease course will improve an individualized approach and guide personalized therapy. • We report a case of low-grade FL with high-risk clinical features that were not captured by its low-grade histologic features, immunophenotypic profile, and a low proliferation index as assessed by Ki67. Immunohistochemistry revealed overexpression of p53 that led to further discovery of concurrent TP53 mutation and 17p deletion in the lymphoma cells. • The presence of TP53 abnormalities in low-grade FL in the absence of morphological transformation is not well-studied. This case highlights the need for molecular and cytogenetic characterization of low-grade FLs beyond morphology-based grading and assessment of proliferation rate. © 2021 Elsevier Inc.