I was diagnosed (finally) with Trousseau's not long after my diagnosis of NSCLC. Thought I would write in a "heads up" from my experience.
Apparently, Trousseau's syndrome has been recognized since the late 1800's as a complication of lung and a few other cancers. I don't understand then why it seems to be low on the radar of treating physicians. I complained of symptoms numerous times, saw my oncologist and my internist, and visited ER's 3 times before the problem was finally discovered—and all through that time I was having horrendous symptoms and could have died suddenly.
In addition to having extreme difficulty breathing, primarily due to severe coughing, my ankles and lower legs were increasingly swollen despite having been up continuously for over a month and wearing pressure stockings. I had already been diagnosed and treated for a pulmonary embolism, but my legs and breathing got worse again as soon as I was off heparin and on Warfarin (the usual post-PE progression). Since my INR's kept going extremely high, no one thought to check for additional blood clot problems until after I arrived again at an ER in screaming leg pain and unable to walk. Even then, the doctors felt sure they would not find new clots. How mistaken they were. . . .
With Trousseau's, there are changes in the blood clotting mechanisms that are not addressed by Warfarin—someone with Trousseau's is likely to fail on Warfarin but needs to stay on heparin to prevent widespread blood clotting, with all of the associated problems (like deep vein thrombosis, pulmonary embolism, periferral vein thrombi, vein inflammation, swollen legs, fluid retention in the tissues but systemic dehydration, etc).
So, if you or your loved one with NSCLC is having increasing difficulties with fluid retention, inflamed veins, etc., perhaps they should be checked for blood clots, e.g., via ultrasound of the legs. Don't rely on Warfarin to solve the problem.