Gout and Cushing....how are they related?

This was a case of a gentleman I saw in MOPD few years ago. He had these changes to his hands. 

From this picture we can see multiple tophi over the dorsum of the hands particularly over the extensor tendons as well as extensor surface of the wrists and distal forearms. There is a particularly large tophi overlying the 2nd metacarpophalangeal joint. 

You will be able to make the diagnosis of gouty arthritis just based on the above photo. However do not stop there. Go further by looking for other clues to suggest a possible aetiology of the gouty arthritis. Look for psoriatic rashes over the dorsum of hands and extensor surfaces of the limbs, also look for nail changes suggestive of psoriasis e.g. pitting nails. And also take the opportunity to look at the forearms for any arteriovenous fistulas to suggest chronic kidney disease that has progressed to end stage disease requiring hemodialysis. CKD can be associated with worsening of gout due to reduced renal clearance. 

This photo further illustrates the extent of gouty tophi deposition over the extensor surfaces and also over the elbows. 

This photo shows tophi on the ear pinna. Tophi formation tend to occur not only on the extensors but also at areas of the body where temperatures are cooler. Cooler temperatures make uric acid deposition easier. That is one reason why tophi is often seen over the distal extremities like the toes (especially the first metatarsophalangeal joint in podagra) and also the pinna. 

But take a look at the next photo. 

Take note that this patient has a body habitus suggestive of Cushing's syndrome. There is central obesity noted. There are also multiple striations over the anterior abdomen due to excessive stretching (the classical purplish or pinkish striae is not clearly seen in this photograph). And in the second photo above, the patient has a thick neck. If seen laterally, this patient also has a dorsocervical hump due to excess fat deposition (not in photo). 

The last photo above also shows multiple hyperpigmented marks on both sides of the umbilicus. Those scars are indicative of recurring injections likely from insulin therapy. Meaning this patient can be suspected to have concomitant diabetes mellitus, a diagnosis which is not surprising considering his physical appearance. This also further strengthens the diagnosis of Cushing's syndrome, of which diabetes mellitus is a feature. 

So now we have two diagnoses:

1. Chronic tophaceous gout

2. Cushing's syndrome 

So how do we tie both the diagnoses? The answer is steroids. If you are able to take one history, I would suggest you to ask about the drug history...the patient would tell you he has been visiting many clinics over the years for joint pains due to gouty attacks. During each visit he will receive a common cocktail of painkillers which often include steroids. On top of that, he also visits retail pharmacies and self medicate his joint pains by purchasing painkillers and steroids over the counter. As a result of the chronic steroid exposure, he has developed secondary Cushing's syndrome which is a complication of trying to treat his gout. Unfortunately, because of no proper follow up, he was not started on uric acid lowering treatment e.g. allopurinol. He will definitely benefit from it. 

CCE.