Prolidase deficiency diagnosed by whole exome sequencing in a child with pulmonary capillaritis

Radiology and histopathology. a, b) Computed tomography (CT) of the chest taken at 16 months of age at presentation of idiopathic diffuse alveolar haemorrhage, demonstrating diffuse ground-glass opacities, interlobular septal thickening and tiny subpleural cystic lesions (arrows). c, d) CT of the chest taken at 5 years of age, demonstrating significant resolution of ground-glass opacities after immunosuppressive therapy, but progression of the interlobular septal thickening and subpleural cysts (now also within a fissural and peribronchovascular distribution), with emergent traction bronchiectasis and fibrosis. e) Histopathology from the biopsy taken at 16 months of age demonstrating lipoid pneumonia (red arrow), cholesterol crystals (black arrow) and hemosiderin-laden macrophages (white arrow); haematoxylin and eosin stain, magnification 4×. f) Electron microscopy shows capillary basement membrane with electron dense mineral deposits (iron calcium phosphate, dark deposits seen along the length of basement membrane, indicated by the red arrow). Scale bar=200 nm.