You might think twice about the phrase "cough up a lung" after reading this.
Doctors aren't quite sure how the clot stayed intact while being coughed up, but Dr Wieselthaler suspects it could be due to the patient's higher level of fibringen in his blood, which acts like a glue.
In other words, the man was rushed to hospital with chronic heart failure and to help his heart, doctors at the University of California - where the man was admitted - connected him to a machine created to maximise blood flow around the body.
A report says the man was was admitted to the intensive care unit at UC San Francisco Medical Center for chronic heart failure.
Doctors placed a ventricular assist device, a heart pump, into him to treat his condition, but he showed signs of respiratory distress.
"We were astonished", Dr Wieselthaler said.
The man coughed up the right bronchial tree.
"It's a curiosity you can't imagine".
On Tuesday, the widely respected journal shared a truly incredible case: a 36-year-old man with aggressive end-stage heart failure had a coughing fit so extreme that he coughed up a six-inch wide blood clot.
A 2005 report in the European Journal of Cardio-Thoracic Surgery refers to a similar case where a pregnant woman coughed up a less-extensive blood clot cast also in the shape of her bronchial tree.
The 25-year-old mum went on to recover fully and delivered a healthy, full-term baby soon after.
The patient later died from heart failure complications.