The patient was the 2nd of 3 living children; born at term in 1998, with no immediate postnatal respiratory distress. The family history was unremarkable for pulmonary or other rare diseases; the parents were consanguineous and of Turkish descent. At age 2 1/2 years during an acute respiratory tract infection with productive cough and fever with no response to antibiotics, intermittent cyanosis occurred and the child was referred to our centre because of chronic tachypnoea and weight loss. Because of a typical chest computed tomography (CT) and chest x-ray ( Figure 1A , B), BAL macroscopic appearance ( Figure 1G ) and microscopy ( Figure 1C , H), and after exclusion of infectious or metabolic causes or malignancy, PAP was suspected and confirmed by histology ( Figure 1F , I). Figure 1 Diagnosis of alveolar proteinosis was suspected based on typical radiological picture in chest x-ray and CT with groundglass attenuation and interstitial thickening, resulting in crazy paving pattern ( Figure. 1 A, B) . Figure. 1 E shows CT after whole lung lavage of the right lung. Macroscopic appearance ( Figure. 1 G) and light microscopy of BAL fluid stained with PAS ( Figure. 1 C, magnification x400) showed extracellular positive proteinaceous material, lipid-laden macrophages ( Figure. 1 H, MGG stain, magnification x1000), and after exclusion of infectious or metabolic causes or malignancy, PAP was confirmed by histology (right lower lobe). HE stained tissue demonstrated alveolar filling with eosinophilic material ( Figure. At presentation the child had global respiratory insufficiency, combined with an elevated level of LDH and CEA ( Figure 2A ). Based on the clinical diagnosis of alveolar proteinosis we initiated whole lung lavages and some additional treatments.