A man coughed up a blood clot in the exact shape of his lung.
Doctors at the University of California, San Francisco, were left stunned when a 36-year-old patient with advanced heart failure coughed up a massive blood clot – perfectly shaped like the branching airways of his right lung.
The man’s heart condition was so severe that he was placed on a ventricular assist device to help pump blood. To prevent clots from forming in the machine, he was on powerful blood thinners – but these also increased his risk of internal bleeding. Over several days, he had occasional coughing fits that brought up small amounts of blood.
Then, during an extreme bout of coughing, something extraordinary happened: he expelled an intact “cast” of the right bronchial tree – a nearly flawless mold of the lung’s airway passages, made entirely of clotted blood.
While patients sometimes cough up bronchial casts made of mucus or lymph, casts made purely of blood are almost unheard of. Blood is too fragile to hold such a complex structure together – but doctors believe that in this case, a lung infection raised the man’s fibrinogen levels, a clot-forming protein, making the clot sturdy enough to stay intact.
Sadly, the patient died a week later from complications of heart failure. But the case, published in The New England Journal of Medicine, is now a rare teaching example into the hidden architecture of the human lung.













