CD19-negative B-lineage acute lymphoblastic leukemia: A diagnostic and therapeutic challenge

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Date: October-December 2017
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 1,170 words
Lexile Measure: 1350L

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Byline: Shashi. Bansal, Upendra. Sharma, Akansha. Jain, Richa. Sharma, Bhargav. Yagnik

B-lineage acute lymphoblastic leukemia (B-ALL) is an aggressive neoplasm of B-lymphocyte precursors that express the pan B-cell marker CD19 in all the cases. Rarely, a case may be assigned as B-lineage even if CD19 is negative. Here, a 16-year-old male presented with complaints of pain abdomen, on and off fever, joint pain, and hepatosplenomegaly for 2 months. Bone marrow examination was suggestive of acute leukemia with numerous leukoblasts on aspiration. On flow cytometry, gated blast population was negative for CD19, cytoCD3, and myeloperoxidase MPO and positive for CD34, TdT, HLA-DR, CD22, CD79a, and CD10. Immunohistochemistry study showed positivity for TdT, CD34, CD10 (focal), and PAX 5 and negativity for CD20, CD3, MPO, CD117, and CD68. Lack of awareness of negative CD19 expression in B-ALL can lead to incorrect immunophenotypic diagnosis, treatment, and monitoring of B-ALL. Proper diagnosis should be based on clinical features, immunophenotypic profiles, immunohistochemistry findings, and molecular analysis.

Introduction

Acute lymphoblastic leukemia of B-lineage (B-ALL) is an aggressive neoplasm of B-lymphocyte precursors that express the pan B-cell marker CD19 in all the cases. CD19 plays a pivotal role as a 'gating' antigen in the analysis of leukemic cells by flow cytometric immunophenotyping (FCI). CD19 gene is located on the short arm of chromosome 16, 16p11.2. Expression of CD19 on blasts is considered as the most reliable marker for assigning them to the B-lineage. Rarely, a case may be assigned as B-lineage even if CD19 is negative. Hence, it would be challenging to diagnose and treat B-ALL without CD19 expression.

Case Report

A 16-year-old male patient presented with complaints of pain abdomen, on and off high-grade fever, and joint pain for 2 months. Ultrasonography revealed hepatosplenomegaly. Complete blood count analysis...

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Gale Document Number: GALE|A523653885