The differential diagnosis of dyspnea in patients with prior malignancy and nondiagnostic chest radiographs is broad. We report a case of breast carcinoma diffusely metastatic to the bronchial submucosa presenting as obstructive airway disease. Chest radiographs failed to suggest metastatic disease as the cause of dyspnea. CT, however, revealed the unusual finding of diffusely thickened and narrowed airways. Carcinoma confined to airway submucosa was identified using bronchial biopsy. We suggest that diffuse airway narrowing from submucosal metastasis can be demonstrated by CT and should be added to the differential diagnosis of dyspnea in cancer patients with nondiagnostic chest radiographs and evidence of airflow obstruction.