FLI1 and MIC2 expression in precursor B-lymphoblastic leukemia with Burkitt-like morphology and extensive extramedullary involvement: A diagnostic challenge in pediatric small round cell tumor

Das, NThakral, DSingh, GMalhotra, APhulware, RHGogia, AGupta, R2020-04-102020-04-102019-12Das N, Thakral D, Singh G, Malhotra A, Phulware RH, Gogia A, Gupta R. FLI1 and MIC2 expression in precursor B-lymphoblastic leukemia with Burkitt-like morphology and extensive extramedullary involvement: A diagnostic challenge in pediatric small round cell tumor. Indian Journal of Pathology and Microbiology. 2019 Dec; 62(4): 614-6170377-49290974-5130http://imsear.searo.who.int/handle/123456789/196408Pediatric small round cell tumors (PSRCTs) constitute a large proportion of childhood malignancies with overlapping diagnostic and clinical features but radically different therapies. Here, we report a case of 16-year-old male child presenting with diffuse abdominal and mediastinal mass, axillary lymphadenopathy, and pleural effusion. Bone marrow aspirate showed near total replacement by small round malignant cells. The bone marrow biopsy showed interstitial infiltration by malignant cells, which were CD45? CD3? CD20? MIC2+ FLI1+ and diagnosis of Ewing's sarcoma was established. In contrast, flowcytometric immunophenotyping of the bone marrow aspirate showed CD45? cells, which were CD19+ cytCD79a+ CD10+ CD81+ CD38+ HLA-DR+ CD22+ CD20? consistent with B-cell acute lymphoblastic leukemia (B-ALL). The extended immunostaining panel on bone marrow biopsy also showed positivity for cytCD79a, CD10, CD19, and BCL-2, whereas fluorescent in-situ hybridization for EWSR1 gene rearrangement was negative. Thus, a final diagnosis of CD45? FLI1+ MIC2+ B-ALL was established. Rare cases of CD45? B-ALL with immunoreactivity for MIC2 and Friend leukemia virus integration 1 (FLI1) have posed a diagnostic challenge for PSRCTs in the recent past. This case report highlights the role of multimodality approach in establishing a correct diagnosis in CD45? PSRCTs to ensure definitive therapy and better clinical outcome.B-ALLFLI1MIC2multiparametric flow cytometrypediatric small round cell tumors (PSRCTs)FLI1 and MIC2 expression in precursor B-lymphoblastic leukemia with Burkitt-like morphology and extensive extramedullary involvement: A diagnostic challenge in pediatric small round cell tumorJournal ArticleIndiaLaboratory Oncology Unit, Dr. BRAIRCH, All India Institute of Medical Sciences, New Delhi, IndiaDepartment of Pathology, Dr. BRAIRCH, All India Institute of Medical Sciences, New Delhi, IndiaDepartment of Medical Oncology, Dr. BRAIRCH, All India Institute of Medical Sciences, New Delhi, India