Trousseau sign of malignancy, often just referred to on the series as Trousseau's sign, consists of a series of tender, palpable areas of inflammation caused by blood clots. It is caused by a change in the consistency of blood rather than any localized inflammation. It is an indication of a cancer affecting either the lungs, stomach or pancreas.
The sign was first described by French physician Armand Trousseau in the 1860's, who first realized its connection to cancer and blood composition. Ironically, he later identified the sign appearing on himself and later died of gastric cancer.
As the clots themselves are dangerous, heparin is usually administered along with any other treatment for the underlying cancer.