Pulmonary alveolar proteinosis and Niemann Pick disease type B: An unexpected combination

BACKGROUND Pulmonary involvement in Niemann-Pick disease (NPD) is a common finding, especially in type B. It usually manifests with symptoms of restrictive lung disease appearing in adulthood but showing gradual deterioration over time. Treatment options have been dramatically limited, with whole lung lavage offering only temporary improvement. Pulmonary alveolar proteinosis (PAP) has been previously mentioned as part of lung disease in NPD, but only in rare cases of type C2. This is the first study that reports the coexistence of autoimmune PAP with NPD type B. CASE PRESENTATION An 8 year old female patient with the diagnosis of NPD type B and a 2-year history of respiratory symptoms, presented with another episode of severe respiratory distress. Chest imaging revealed a "crazy paving pattern", raising concern for PAP. After admission to the intensive care unit and application of non-invasive positive pressure ventilation, a whole lung lavage was performed with return of a milky-appearing proteinaceous fluid. Her status post-lavage was markedly improved, while genetic testing placed the diagnosis of autoimmune PAP. The patient was initiated on inhaled GM-CSF treatment and shows a beneficial outcome to date. CONCLUSIONS In spite of the patient's symptoms being consistent with NPD type of lung involvement, clinical findings raised the suspicion of an underlying disorder, which surprisingly proved to be PAP. The detection of anti-GM-CSF autoantibodies in our patient allowed the initiation of inhaled GM-CSF treatment, which is likely to prove more beneficial in her prognosis than repeated lung lavages.