Clinicopathologic conference: a 28-year-old woman with perioral cyanosis and low oxygen saturation.

The authors present a case of a 28-year-old woman on trimethoprim/sulfamethoxazole for 9 months, who presented to the emergency department with weakness, shortness of breath, and cyanosis. The patient's clinical course is outlined. A discussion of the potential etiologies, as well as the clinical management, is provided.