Pulmonary involvement by Niemann-Pick disease. A report of six cases

Although pulmonary involvement is a known cause of morbidity in Niemann-Pick disease, histological features in the lung are not well characterized. The purpose of this study is to document the histological features seen in pulmonary involvement by types B and C Niemann-Pick disease and to correlate them with clinical and imaging data.

Surgical lung biopsies from six patients (four with type B and two with type C disease) were reviewed and all showed diffuse endogenous lipid pneumonia, with lesser involvement of the interstitium by fibrosis and foamy macrophage accumulation. In type B disease only, there was also fine cytoplasmic vacuolation within the cytoplasm of ciliated epithelial cells. Neither disease showed foamy changes within pneumocytes. One patient had a bronchial cast removed on whole lung lavage. Electron microscopy showed abnormal lamellar inclusions within lysosomes of affected cells in type B disease. In patients with type C disease, biopsies were undertaken as part of investigations into acute respiratory failure in the context of multiorgan systemic presentation. Three patients with type B disease had clinical disease limited to the lung, all adults (mean age of 40 years) with unexplained diffuse parenchymal lung disease and mainly ground-glass shadowing on high-resolution computed tomography.

Niemann-Pick disease should be considered for any patient with unexplained diffuse endogenous lipid pneumonia, even when disease is limited to the lungs and presentation is during adulthood.