Why does this man have backache and swollen ankles?

The patient This man had been having lower back pain for about six months and was seeing a physiotherapist who had told him to ‘see your GP about getting a scan'. He said his lower legs had lately been a bit swollen. As he pulled up his trousers to show me, I found he had pitting oedema to his knees, which had come on over a few weeks. He had also had some problems maintaining an erection, which he put down to the emotional impact of starting IVF with his fiancée. He was on no regular medication. He was pretty keen on an MRI scan of his lower back, as he'd had right-sided lumbago for a few months that hadn't responded to analgesia or physiotherapy. I explained to him this wouldn't be appropriate at this point, suggesting we start investigating his problems with a blood test. First instinct Examining him, his abdomen was soft and had no masses. Cardiorespiratory examination was normal and there was no inguinal lymphadenopathy. At his age, I thought the most likely diagnosis was on a renal pathology – and this suspicion was strengthened when his U&Es came back showing a creatinine of 142, a little high for a 42-year-old. Differential diagnoses • Nephropathy • Venous insufficiency • Congestive heart failure • Pelvic venous obstruction. I discounted my main differential – intrinsic renal disease – when a dipstick was clear of protein and the lab result showed no suggestion of microalbuminuria. He was a little young to have venous insufficiency and there were certainly no varicose veins. His heart sounds were normal, jugular venous pressure was not raised and B-type natriuretic peptide (BNP) was normal, which ruled out heart failure – although even if it had been raised, it's worth noting that BNP can be pushed up in renal failure in the absence of left ventricular failure. There were no objective signs of pelvic venous obstruction, although this was mainly limited to my examination of inguinal nodes. Getting on the right track Events overtook us when he came back less than a week later with a grossly swollen right leg, was admitted to hospital with a femoral DVT and was given warfarin. It was there that a small lump on the superior pole of the right testis was found and confirmed on ultrasound. The following abdominal and pelvic CT showed widespread retroperitoneal lymphadenopathy. The lymph glands were compressing a ureter, hence the rise in creatinine. They were also responsible for his lower back pain, which explained why physiotherapy hadn't helped. He was transferred to a tertiary centre where the first cycle of chemotherapy for the testicular tumour was followed by an improvement in leg swelling. How will this change my practice? When a man presents with swollen legs, I'll now examine his testicles. Dr Oliver Starr is a GP in Stevenage, Hertfordshire Why does this man have backache and swollen ankles?