Pulmonary Alveolar Microlithiasis: A Case Report

Pulmonary alveolar microlithiasis (PAM) is a rare disorder characterized by diffuse bilateral filling of the pulmonary alveoli by numerous calcific concentrations known as calcispherites. The radiological lesions in PAM closely resemble miliary tuberculosis. PAM should be suspected in cases when the radiological lesions do not correlate clinically. This may reduce the need for invasive procedures in a limited resource setting. A 40-year-old male agricultural laborer, never smoker presented with 10 months history of cough with expectoration and exertional breathlessness. He had completed 6 months of anti-tuberculosis treatment for the same complaints 4 months back. His general physical examination was unremarkable and he was not hypoxic at room air. On auscultation of the respiratory system, he had fine crackles in the left axillary region. Chest X-ray revealed bilateral diffuse nodular lesions with translucent band in bilateral upper zone (black pleura sign). Possibility of PAM was considered and it was confirmed with high resolution computed tomography of chest. Fiberoptic bronchoscopy was done. The bronchial brushings and washings revealed numerous calcific concretions of alveolar macrophages. Calcispherites were also demonstrated by percutaneous lung biopsy.