Pulmonary alveolar microlithiasis and lymphocytic interstitial pneumonitis in a ten year old girl. 
Pulmonary alveolar microlithiasis (PAM) is a rare lung disease, characterized by progressive formation of intra-alveolar calculi in response to an unknown stimulus.  We report an unusual presentation of PAM in a 10 year old girl with clinically significant interstitial lung disease and histological evidence of both PAM and lymphocytic interstitial pneumonitis.  A rapid improvement of pulmonary function and exercise tolerance was seen in response to glucosteroid therapy.