Autoimmune PAP (aPAP) in children

Abstract

In childhood, a multitude of causes leads to pulmonary alveolar proteinosis (PAP), an excessive surfactant accumulation in the alveolar space limiting gas exchange. Autoantibodies against GM-CSF causing autoimmune PAP, the principle etiology in adults, are rare.In this first series on autoimmune PAP we detail the presentation and management issues of four children.Whereas three children presented insidiously with progressive dyspnea, one was acutely sick with suspected pneumonia. During management, one patient was hospitalised with COVID-19, non-invasively ventilated, and recovered. All treatment modalities known from adults including whole lung lavages, augmentation of GM-CSF by inhaled GM-CSF, removal of neutralising antibody by plasmapheresis and interruption of antibody production by Rituximab were considered, however not all options were available at all sites. Inhaled GM-CSF appeared a non-invasive and comfortable therapeutic approach.The management with best benefit to harm ratio in autoimmune PAP is unknown and specialised physicians must select the least invasive and most effective treatment. To collect this cohort in a rare condition became feasible as patients were submitted to an appropriate registry. To accelerate authorisation of novel treatments for autoimmune PAP competent authorities should grant an inclusion of adolescents into trials in adults.