Which tissue should be sampled to diagnose Polyarteritis nodosa?
The likelihood of finding arteritis is greatest when symptomatic sites are examined.
The most accessible tissues are skin, sural nerve, skeletal muscle, rectum, and testicle.
Renal biopsy is usually nondiagnostic unless a medium-sized artery is in the biopsy specimen.
There is also an increased risk of bleeding due to microaneurysms in the kidney. Biopsy of asymptomatic sites is not recommended due to their low yield. A sural nerve biopsy should never be done in patients with a normal electromyogram.
