Alveolarproteinosis, an orphan disease.

Typical microscopic features of PAP in bronchoalveolar lavage (BAL)

Pulmonary Alveolar Proteinosis (PAP), first described by Rosen and Castleman in 1958, is a rare syndrome characterized by the intra-alveolar accumulation of surfactant lipids and proteins, leading to impaired gas-exchange and resulting in progressive respiratory insufficiency. The current knowledge about PAP is based on small series and individual case reports. While data from these studies have been synthesized into a comprehensive review in 2002, these data represent cases across nearly half a century. However the incidence, prevalence and the natural history of primary PAP have been recently assessed in a large cohort study of PAP patients in Japan, showing differences in some respects with previous published data. If these differences are due to ethnic backgrounds, it could be explained only through a large cross-sectional study that evaluates geographically distributed, ethnically diverse groups of patients. PAP is recognized to occur in four distinct clinical forms: primary, secondary, congenital and idiophatic, or PAP-like.

Physical examination is often normal or reveals relatively minor and nonspecific pulmonary findings; digital clubbing is uncommon. Progressive dyspnea of gradual onset, associated with a minimally productive cough, fatigue, weight loss and low-grade fever are the most common symptoms.

Healthy Alveolar Macrophage

Healthy Alveolar Macrophage

Concerning the diagnosis, BAL con can confirm the diagnosis and replace lung biopsy in PAP. the BAL fluid is macroscopically milky and turbid adn microscopically shows a typical constellation of findings (acellular oval bodies, amorphous debris, foamy macrophages). Only in few cases the lung biospsy (transbronchial or surgical) is necessary. The autoimmune acquired form of disease needs confirmation through the detection of anti-GM-CSF antibodies in serum. This test may be performed only in specialized centers.

The current mainstay of treatment for pulmonary alveolar proteinosis (PAP) is whole-lung lavage (WLL), a delicate procedure that requires an eŃ…perienced team. Therapy with granulocyte-macrophage colony-stimulating factor is a possibility, although its long-term efficacy has not been determined. There are running studies to evaluate the combination of inhalative GM-CSF and WLL in patients with frequent relapses.