[Pulmonary alveolar proteinosis].

Pulmonary alveolar proteinosis (PAP) is a rare, diffuse infiltrative lung disease of unknown etiology characterized by accumulation of abnormal lung surfactant in the alveoli and distal airways. Although it was first described in 1958, few large scale studies have been published. The diagnosis is conventionally based on lung biopsy and the value of less invasive procedures such as bronchoalveolar lavage (BAL) remains controversial. A multi-center retrospective study was conducted in an attempt to update epidemiological, clinical and long term outcome and to assess the usefulness of chest CT scan and BAL in the management of a large homogeneous series of 41 patients. Inclusion criteria required a clinical picture compatible with PAP and either histological confirmation, or a BAL with a milky macroscopic appearance coupled with positive staining to PAS. Mean age was 48.8 years with a 4: 1 male predominance. The prevalence of smokers (80%) and occupational exposure to various inhaled dusts (39%) was high. The clinical, roentgenographic and functional features were in keeping with previous series. Worsening dyspnea was the most common symptom. Other common manifestations were dry cough, recurrent lung infections, weight loss, finger clubbing, crackles and cyanosis. LDH serum levels were increased in 51% of cases. Lung function tests usually showed a mild restrictive ventilatory defect with hypoxemia and reduced DLCO. Chest X ray revealed bilateral ground glass opacities with consolidation or air bronchogram involving peri-hilar or lower lobes. Chest CT scan, performed in 38 patients, revealed a similar pattern in most of them with diffuse intra-alveolar ground glass opacities (33/38) and interlobular thickening (35/38), resulting in a crazy paving appearance in the typical geographic pattern (32/38). This latter aspect was highly suggestive of the diagnosis. Segmental BAL led to a definitive diagnosis in 62% and lung biopsy was only required in 38% of cases. These data suggest that careful BAL analysis can be sufficient to provide a diagnosis without the need for a lung biopsy. During follow-up, spontaneous remission or improvement was reported in 26%. Segmental (n=3) or whole lung lavage (n=22) was required in 62.5% with a favorable course (complete remission 37%, improvement 34%, stable course 21%) in 92% of the cases. In this series the overall prognosis for PAP remained good, although unpredictable.