Pediatric Erythroid Sarcoma Diagnostically Confirmed by Identification of a Recurrent NFIA::CBFA2T3 Fusion.

Erythroid sarcoma (ES) is exceedingly rare in the pediatric population with only a handful of reports of de novo cases, mostly occurring in the central nervous system (CNS) or orbit. It is clinically and pathologically challenging and can masquerade as a nonhematopoietic small round blue cell tumor. Clinical presentation of ES without bone marrow involvement makes diagnosis particularly difficult. We describe a 22-month-old female with ES who presented with a 2-cm mass involving the left parotid region and CNS. The presence of crush/fixation artifact from the initial biopsy made definitive classification of this highly proliferative and malignant neoplasm challenging despite an extensive immunohistochemical workup. Molecular studies including RNA-sequencing revealed a NFIA::CBFA2T3 fusion. This fusion has been identified in several cases of de novo acute erythroid leukemia (AEL) and gene expression analysis comparing this case to other AELs revealed a similar transcriptional profile. Given the diagnostically challenging nature of this tumor, clinical RNA-sequencing was essential for establishing a diagnosis.

Biliary atresia liver histopathological determinants of early post-Kasai outcome.

BACKGROUND: A retrospective chart review of liver histologies in Kasai biliary atresia BA patients operated 1/2017- 7/2019 at our institution was conducted to identify histologic prognostic factors for biliary outcome. METHODS: Patients with wedge liver biopsies and portal plate biopsies (n = 85) were categorized into unfavorable and favorable outcome, based on a 3-month serum total bilirubin level of <34 µM or mortality. Hepatocellular histologies, presence of ductal plate malformation (DPM) and of large bile duct of ≥ 150 µm diameter size at the portal plate were evaluated. RESULTS: Total Bilirubin levels> 34 µM correlates with worse 1-year survival. Age at surgery, histologic fibrosis or inflammation does not predict outcome. Potential adverse predictors are severe hepatocellular swelling, severe cholestasis, presence of DPM (n = 24), and portal plate bile duct size < 150 µm (n = 28). In multivariate analyses adjusting for age at Kasai and postop cholangitis, bile duct size and severe hepatocellular swelling remain independent histologic prognosticators (OR 3.25, p = 0.039 and OR 3.26, p = 0.006 respectively), but not DPM. CONCLUSION: Advanced histologic findings of portal plate bile duct size of <150 µm and severe hepatocellular damage predict poor post-Kasai jaundice clearance and short-term survival outcome, irrespective of Kasai timing. LEVEL OF EVIDENCE: Level III.