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pulmonary alveolar phospholipoproteinosis; alveolar proteinosis; pulmonary surfactant metabolism dysfunction; inborn error of pulmonary surfactant metabolism

Etiology: 1) 95% idiopathic 2) excessive production of alveolar surfactant &/or diminished clearance of surfactant by alveolar macrophages 3) genetic Epidemiology: 1) rare 2) affects mostly young adults 3) male:female ratio 3:1 Pathology: 1) alveoli contain PAS+ granular eosinophilic material 2) alveolar material is largely dipalmitotyl lecithin Genetics: - autosomal recessive - associated with defects in CSF2RB - associated with defects in SFTPB (type 1) - associated with defects in SFTP (type 2) - associated with defects in ABCA3 (type 4) Clinical manifestations: 1) initial febrile episode 2) disease-free interval of weeks to months after initial febrile episode (2-12 months) 3) progressive dyspnea 4) productive cough 5) diffude crackles, bilateral 5) low-grade fever 6) chest pain 7) weight loss 8) autosomal recessive form fatal Special laboratory: 1) pulmonary function testing: a) restrictive pattern b) decreased DLCO 2) bronchoscopy a) bronchioalveolar lavage - respiratory cultures are negative b) lung biopsy - alveoli filled with lipoproteinaceious material Radiology: 1) chest X-ray a) alveolar infiltrates in the lower 2/3 of lungs b) may resemble pulmonary edema c) costophrenic angles are spared 2) high-resolution computed tomography (HRCT) - characteristic 'crazy paving' pattern [2] - thickened septal lines with ground-glass opacities Differential diagnosis: (similar histopathology) 1) silicosis 2) mycobacterial infection 3) mycoses 4) leukemia 5) pneumocystis infection Complications: - Nocardia infection Management: 1) whole lung lavage to remove intra-alveolar material [3] 2) spontaneous resolution occurs in 1/3 of patients

Related

bronchoalveolar lavage (BAL) Nocardia periodic acid Schiff base (PAS) pulmonary surfactant-associated protein B; SP-B; 18 kD pulmonary-surfactant protein; 6 kD protein; pulmonary surfactant-associated proteolipid SPL(Phe) (SFTPB, SFTP3)

General

lung disease lipid metabolism, inborn error; lipid storage disease; lipidosis

Database Correlations

OMIM correlations

References

  1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 756
  2. Medical Knowledge Self Assessment Program (MKSAP) 14, American College of Physicians, Philadelphia 2006
  3. Abdelmalak BB, Khanna AK, Culver DA, Popovich MJ. Therapeutic Whole-Lung Lavage for Pulmonary Alveolar Proteinosis: A Procedural Update. J Bronchology Interv Pulmonol. 2015 Jul;22(3):251-8 PMID: 26165897