Hemophagocytic lymphohistiocytosis and pulmonary alveolar proteinosis in a 13-month-old boy with lysinuric protein intolerance

Hemophagocytic lymphohistiocytosis (HLH) is a clinical syndrome that can be inherited or acquired. Herein, we report a case of HLH and pulmonary alveolar proteinosis (PAP) in the setting of lysinuric protein intolerance (LPI) in a male toddler who presented with prolonged fever, respiratory distress, and failure to thrive. On histologic examination, hemophagocytosis was observed in lymph node, bone marrow sections and aspirates. Lung wedge resection was consistent with PAP. LPI was confirmed with genetic sequencing which revealed compound heterozygous mutations in the SLC7A7 gene. LPI is a rare inborn error of metabolism and is not widely known beyond the pediatric group. Though the association of LPI with HLH has been previously described, we believe this is the first reported case of HLH and PAP associated LPI with histopathological correlation. Early recognition of HLH is critical to successful treatment and LPI should be considered in any young infant who presents with HLH- and PAP-related symptoms.