Rectal biopsy in the diagnosis of systemic vasculitis.

Vasculitis has been seen in rectal biopsies from 22 patients over a six year period. The most common finding was a necrotising vasculitis of small arteries, indistinguishable from that seen in polyarteritis nodosa (PAN). Sub-acute, chronic ("burnt out") and leucocytoclastic changes were also seen. Sixteen patients had vasculitis complicating rheumatoid arthritis (RA), 3 PAN and 3 overlap syndromes. Patients with RA and rectal vasculitis had a higher mortality, and a greater incidence of neuropathy than those with negative biopsies. An adequate biopsy is positive in 40% of patients with clinical vasculitis and RA but was only positive in one of a control series of 46 RA patients with no clinical vasculitis. Rectal biopsy in experienced hands is a safe, and repeatable procedure. It is useful as a "blind" biopsy site in the diagnosis of systemic vasculitis, especially that complicating RA. It can also be used for serial studies of the evolution of vasculitis. Serial sections of the entire biopsy may be required to reveal the vasculitis which is often focal in nature.