You might think twice about the phrase "cough up a lung" after reading this.
This kind of clot isn't unheard of in patients, but what was unusual was how intact it was.
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.
The New England Journal of Medicine reports that a 36-year-old man with a lengthy medical history experienced increasing respiratory distress before shocking doctors at the University of California at San Francisco.
More specifically it's a six-inch-wide, unbroken cast of the right bronchial tree, part of the tubular network that distributes air to the lungs.
After previously coughing up other, smaller blood clots, the man let out a big one, and up came this folded-over clot in the exact shape of his right bronchial tree, one of the primary parts of the lung.
Dr Wieselthaler carefully spread out the coughed-up clot, realising it was the ideal shape.
"We were astonished", he said. But because these machines can also increase the risk of blood clots, he was prescribed a blood-thinner medication. "It's a curiosity you can't imagine-I mean, this is very, very, very rare".
Fibrinogen is a type of protein in the blood that works to glue platelets together.
Last week, a hospitalized California man coughed up an intact cast of part of his right lung, a colossal blood clot almost six inches wide.
After coughing up the bronchial tree, doctors immediately intubated him and performed a bronchoscopy, but he later died from heart failure complications ('volume overload and poor cardiac output'), despite the placement of the ventricular assist device.