A Curious Case of Morphologically Deceptive Pediatric B-Lymphoblastic Leukemia with Granular "Blebbed" Blasts and DLBCL-Like Biopsy Findings

Background: B-cell acute lymphoblastic leukemia is known for heterogeneous blast morphology. Cytoplasmic granules and blebs have both been described, but not together, in lymphoblasts. Case presentation: A 7-year-old boy presented with fever, abdominal distension for 3 weeks, with hepatosplenomegaly. Investigations revealed pancytopenia, peripheral smear showing 21% blasts of varying size, displaying cytoplasmic blebbing and granulation. Marrow aspirate was hemodilute, 10% cells showed dim to moderate expression of CD45, CD10, CD19, HLA-DR confirming B-ALL. Megakaryocytic markers (CD41, CD61) were negative. Marrow biopsy showed a focus of large atypical cells displaying increased nuclear-cytoplasmic ratio, vesicular nuclear chromatin and macronucleoli, reminiscent of diffuse large B-cell lymphoma, cells strongly expressing PAX5, CD19, CD20, and bcl-2.The child was put on standard induction therapy. No blasts were detected in subsequent peripheral smears. Conclusion: To the best of our knowledge, this is the first case of pediatric B-ALL displaying granular "blebbed" blasts.