BACKGROUND Dyspnea in pregnancy is common and attributable to a variety of etiologies including normal physiology. The obstetric provider is challenged with distinguishing between physiologic versus pathologic dyspnea. CASE REPORT A 31-year-old G2 P1001 female at 34 weeks gestation presented with dyspnea, tachycardia, and inability to lie supine. Imaging revealed a large heterogeneous anterior mediastinal mass (14.8×11.5 cm). Multidisciplinary coordinated care led to diagnosis of B cell lymphoma, delivery via cesarean section under regional anesthesia in steep Trendelenberg position, followed by chemotherapy postpartum. CONCLUSIONS Dyspnea in pregnancy is common but might represent underlying pathology. While an obstetrician is knowledgeable of physiologic pregnancy changes, he or she should remain vigilant for underlying pathologic causes of dyspnea, including malignancy. Anterior mediastinal masses propose unique anesthetic challenges including respiratory impairment and cardiopulmonary collapse requiring collaborative care and planning.