Publication Date

9-2025

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Abstract

Introduction: Neonatal onset of cytopenia autoinflammation rash and hemophagocytic lymphohistiocytosis syndrome (NOCARH), a subset of hemophagocytic lymphohistiocytosis (HLH), is a rare and life-threatening condition characterized by uncontrolled immune response. It presents a diagnostic challenge in neonates due to the overlap of clinical features with other conditions, particularly congenital infections. We report a case of NOCARH in a late pre-term neonate, highlighting an atypical age group and the diagnostic difficulty of this syndrome. Case Presentation: A 1 day old ex-35 week er neonate presented to a level 4 NICU with chief complaints of pancytopenia,; an extensive petechialmaculopapular rash of on the her extremities, torso, and face ; e, abdominal distention;, hepatomegaly ; abnormal findings on abdominal film ; , and a systolic murmur . Initial symptoms prompted concern for congenital infection s, as well asand necrotizing enterocolitis. Comprehensive infectious disease testing yielded negative results. She was subsequently evaluated for immunodeficiency, liver, and thyroid associatedrelated diseases. Persistent profound pancytopenia, lymphadenopathy, elevated inflammatory markers, episodic rashes, growth failure, worsening cholestasis, and new onset lymphadenopathy episodic rashes at three weeks of age prompted expansion of differential and evaluation for NOCARH despite not fitting clearly into diagnostic criteria . Bone marrow biopsy confirmed the diagnosis with findings of hemophagocytosis without malignancy. Genetic evaluation identified a heterozygous pathogenic CDC42 mutation consistent with NOCARH syndrome. Management: Treatment included the administration of dexamethasone, intravenous immunoglobulin, and emapalumab, a monoclonal antibody targeting IFN-γ. Prophylactic Aantimicrobials were initiated for prophylaxis in the setting of her immunosuppression. Outcomes and Follow-up: The patient demonstrated clinical stabilization with improved resolving cytopenia and reduction in inflammatory markers. Her health ultimately improved , ultimately being able to beenough to discharged home with close follow-up with specialized care and ongoing multidisciplinarymultiple subspecialists , including Gastroenterology and Oncology follow-up. Bone marrow transplantation is planned to achieve long-term disease control. Conclusion: This case highlights the hazards of anchoring bias when evaluation for initial suspected medical condition is inconclusive. Early diagnosis and targeted therapy are critical to improving outcomes in this rare, high-mortality condition. Pediatricians and neonatologists should be aware of the potential for HLH to present in neonates, particularly in association with genetic syndromes like NOCARH. Introduction: Neonatal onset of cytopenia, autoinflammation, rash, and hemophagocytic lymphohistiocytosis syndrome (NOCARH), a subset of hemophagocytic lymphohistiocytosis (HLH), is a rare and life-threatening disorder driven by uncontrolled immune activation. Diagnosis in neonates is challenging because its features overlap significantly with congenital infections and other systemic inflammatory conditions. We present a case of NOCARH in a late preterm neonate, illustrating the diagnostic complexity and importance of early recognition in an atypical age group. Case Presentation: A 1-day-old ex-35-week neonate was admitted to a level IV NICU with pancytopenia, widespread petechiae, abdominal distention, hepatomegaly, and a systolic murmur. The initial differential diagnosis included congenital infections. Broad infectious workup was unrevealing. Over the next three weeks, the infant exhibited persistent cytopenia, lymphadenopathy, elevated inflammatory markers, and recurrent episodic rashes, raising suspicion for HLH/NOCARH despite not fully meeting diagnostic criteria. Bone marrow biopsy revealed hemophagocytosis without malignancy,

Disciplines

Pediatrics

Notes

Presented at the American Academy of Pediatrics (AAP) 2025 National Conference & Exhibition; September 26-30, 2025; Denver, CO.

No Suspicion for NOCARH: A Cautionary Tale of Anchoring Bias

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