Noninfectious Diffuse Granulomatous Lung Diseases

This chapter illustrates the two main forms of noninfectious diffuse granulomatous lung disease likely to be encountered in lung biopsies: hypersensitivity pneumonia and sarcoidosis. Hypersensitivity pneumonia and sarcoidosis have in common an ability to cause respiratory symptoms in patients with diffuse radiologic abnormalities. Affected patients frequently undergo biopsies to rule out neoplasms and/or other forms of diffuse lung disease. Non-necrotizing granulomatous inflammation is an important diagnostic clue in both conditions, each distinguished by a very different combination of associated histologic findings. When encountered by surgical pathologists, the differential diagnosis for both often includes granulomatous infections, an especially important consideration in immunocompromised patients (see Chap. 4). Other conditions that may enter the differential diagnosis include aspiration pneumonia, which is illustrated in Chap. 5.