Context.—Patients with pneumothorax occasionally require limited lung resections to control persistent air leaks. In some patients, especially smokers, histopathologic findings suggest that a ruptured bulla or bleb caused the pneumothorax. Other patients only exhibit histopathologic changes related to the physical trauma of acute, and likely occult recurrent, peripheral lung injury in the setting of “spontaneous,” or idiopathic, lung rupture. Sometimes, pneumothorax occurs secondary to an underlying localized or diffuse parenchymal lung disease. A comprehensive description of the morphologic findings that may be seen in these specimens will help the surgical pathologist distinguish patients with more common and indolent occurrences of pneumothorax from those requiring additional workup or treatment.Objective.—To develop a diagnostic approach for surgical pathologists encountering lung specimens obtained in the context of pneumothorax repair.Data Sources.—Literature review and consultation experience of the authors.Conclusions.—Two general categories of histopathologic changes can be identified: (1) nonspecific changes, reflecting the lung's acute and chronic response to localized injury, and (2) changes suggesting an underlying lung disease that may have played an etiologic role in the development of pneumothorax. The latter changes are important to recognize because they may require additional workup or treatment of clinically occult lung disease. Difficulty arises when nonspecific histopathologic changes overlap with those of an underlying lung disease. Awareness of these diagnostic challenges and pitfalls, together with clinicoradiographic correlation, is essential in these situations and will help guide the surgical pathologist toward an accurate diagnosis and the appropriate management of clinically occult disease.