Metastatic pulmonary calcification mimicking air-space disease. Technetium-99m-MDP SPECT imaging

Metastatic pulmonary calcification (MPC), a complication of chronic renal failure, is uncommonly diagnosed antemortem, yet may be a significant etiology of pulmonary dysfunction in patients with renal failure. The degree of respiratory distress often does not correlate with the degree of macroscopic calcification. Patients with extensive calcification may be asymptomatic, while others with subtle calcification or normal chest radiographs may have severe respiratory compromise. Additionally, the findings on chest radiographs may be confused with air-space disease, including pulmonary edema and pneumonia. Radionuclide imaging may detect MPC in the setting of normal chest radiographs, and confirm the diagnosis when there are radiographic findings of air-space disease without macroscopic calcification. We present a patient with bilateral upper lobe disease suspected to represent edema or pneumonia, proven to represent MPC on 99mTc MDP scintigraphy with single photon emission computed tomography (SPECT), CT, and later at transbronchial biopsy.