When investigations don't match clinical findings

Earl is an 88-year-old retired teacher who presents to his GP with gross swelling of the left upper limb for the past 24 hours.

The limb feels tight, with associated discomfort. He denies any chest pain or dyspnoea and has otherwise been well.

Earl’s past history includes well-controlled asthma, type 2 diabetes, hypertension, chronic kidney disease, gout, heart failure with preserved ejection fraction and type 2 Mobitz conduction block.

He underwent colonic resection for bowel cancer 20 years ago, has had two melanomas removed (one from the left forearm two years ago, and another from the mid-chest two months ago) and had a pacemaker inserted five months ago without complication.

His medications include allopurinol, aspirin, amlodipine, linagliptin, metformin, atorvastatin, frusemide, spironolactone and inhaled terbutaline and budesonide/formoterol.

He is allergic to ketamine, which causes