From Pancytopenia to Hyperleukocytosis, an Unexpected Presentation of Immune Reconstitution Inflammatory Syndrome in an Infant with Methylmalonic Acidemia
Samuel Sassine,
Amandine Remy,
Tanguy Demaret,
François Proulx,
Julie Autmizguine,
Fatima Kakkar,
Thai Hoa Tran,
Caroline Laverdière,
Ellery T. Cunan,
Catalina Maftei,
Grant Mitchell,
Hélène Decaluwe,
Jade Hindié
Affiliations
Samuel Sassine
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Amandine Remy
Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
Tanguy Demaret
Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
François Proulx
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Julie Autmizguine
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Fatima Kakkar
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Thai Hoa Tran
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Caroline Laverdière
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Ellery T. Cunan
Division of Pediatric Critical Care, Department of Pediatrics, Montreal Children’s Hospital, McGill University, Montreal, QC H3A 0G4, Canada
Catalina Maftei
Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
Grant Mitchell
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Hélène Decaluwe
CHU Sainte-Justine Research Center, Montreal, QC H3T 1C5, Canada
Jade Hindié
Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
A 2.5-month-old girl admitted for failure to thrive and severe pancytopenia was diagnosed with methylmalonic acidemia (MMA) secondary to transcobalamin II deficiency, an inborn error of vitamin B12 metabolism. Opportunistic Cytomegalovirus and Pneumocystis jirovecii pneumonia led to severe acute respiratory distress syndrome (ARDS) and immune reconstitution inflammatory syndrome (IRIS) after treatment initiation with vitamin B12 supplementation. In children with interstitial pneumonia-related ARDS, normal lymphocyte count should not delay invasive procedures required to document opportunistic infections. MMA can be associated with underlying lymphocyte dysfunction and vitamin B12 supplementation can fully reverse the associated immunodeficiency. IRIS may appear in highly treatment-responsive forms of pancytopenia in children and prompt treatment of dysregulated inflammation with high-dose corticosteroids should be initiated.
