Absence of pulmonary uptake of Tc-99m methylenediphosphonate in alveolar microlithiasis.

Pulmonary alveolar microlithiasis (PAM) is a rare disease of unknown etiology characterized by accumulation of calcific concretions in the alveolar spaces. The paper reports a case of PAM in a 56-year-old male. The patient had persistent dry cough, and gradually progressive dyspnea on exertion. The diagnosis was established on the basis of roentgenography and confirmed by the sputum and transbronchial biopsy findings. Scintigraphy revealed the absence of Tc-99m methylenediphosphonate uptake of lungs. Familial occurrence was not observed. Chest roentgenogram, pulmonary function, and clinical status of the patient have remained stable for 41 months. Radiological and clinical follow-up of the disease continues.