Key Points

• Thoracic surgeons evaluate two distinct patient populations with interstitial lung disease: those with acute respiratory illness, often with impaired immunity, and those with progressive dyspnea and an insidious decline in lung function.
• The goal of a surgical lung biopsy is to define pathology leading to revised therapy that in turn leads to improved outcome.
• Surgical lung biopsy has greater utility in classifying the disorder and leading to effective therapy if it is performed early in the disease process.
• Thoracoscopic and open lung biopsy techniques provide equivalent diagnostic information.
• Thoracoscopy is the procedure of choice in the elective setting.

Interstitial lung disease (ILD) is a heterogeneous group of lung conditions of both known and unknown etiology. There are more than 200 different diseases in the group, which broadly can be divided into infectious, occupational, iatrogenic, granulomatous, malignant, autoimmune/connective tissue disorder-related, and idiopathic categories (Table 1).[1] The incidence and mortality from ILD seems to be increasing.[2] Despite disparate etiologies, they often have similar clinical features, including dyspnea and hypoxemia, restrictive spirometry, depressed diffusion capacity, and a diffusely abnormal interstitium on lung imaging. The presentation of the idiopathic etiologies can vary from a slow, insidious presentation to subacute lung failure with a wide variety of expected responses to therapy (Table 2). Patients with ILD present a therapeutic conundrum for clinicians because these varied disorders with similar clinical presentations often require radically different therapies (e.g., antimicrobial therapy versus augmented immunosuppression).