Bronchioloalveolar adenocarcinoma (BAC) is a subtype of lung adenocarcinoma characterized by malignant cell growth occurring in the alveolar septa. Risk factors are smoking (although BAC may also occur in nonsmokers) and occupational exposures. Clinical presentations are variable. Localized disease is more common; patients present with a solitary peripheral nodule or multifocal pulmonary nodules. In extensive disease, patients may have lobar consolidation. Symptoms depend on the presentation of the disease (localized or extensive). Patients with localized disease often present with no symptoms. In patients with extensive tumors, the most common signs and symptoms include cough, dyspnea, and hemoptysis; less common signs and symptoms include fever and weight loss.

BAC usually presents in females in the seventh decade of life, and although associated with patients who currently smoke or formerly smoked, the association is weak compared with other forms of lung cancers.

Treatment is tailored to the patient and their stage in the disease. Surgical resection and radiation therapy are standard treatments for patients with locoregional disease. Chemotherapy and targeted therapy are used to treat patients with advanced disease.