Role of bone scanning in pulmonary alveolar microlithiasis report of two cases

Two cases of pulmonary alveolar microlithiasis showing intense pulmonary uptake of Tc-99m MDP are reported. Pulmonary alveolar microlithiasis, which is a relatively rare disorder of unknown etiology, is characterized by the presence of innumerable tiny calcispherytes within the alveoli of the lungs. A local defect of the calcium metabolism has been implicated as the possible etiologic factor of this disorder. The calcispherytes, ranging between 0.01 to 0.3 mm in diameter, are composed chiefly of calcium and phosphorus, with apatite as the major chemical state. This chemical composition of the microliths is most probably responsible for the uptake of the bone seeking radiopharmaceutical in the lungs.