Alveolar Sarcoidosis With Intense FDG Uptake, Mimicking Multi-focal Pneumonia and Infiltrative Lung Malignancy.

Alveolar sarcoidosis is an uncommon radiologic manifestation of pulmonary sarcoidosis which appears as infiltrative or mass-like opacities mimicking multifocal pneumonia or infiltrative lung malignancies such as multi-focal adenocarcinoma or pulmonary lymphoma. It has correlation with a more acute and symptomatic phase of thoracic sarcoidosis and therefore expected to show a more severely increased metabolic activity on FDG PET. Alveolar sarcoidosis shows a relatively rapid radiological improvement after initiation of corticosteroid therapy. Tissue diagnosis might be needed in some cases to exclude malignancy.