111Indium-labelled polymorphonuclear leucocyte scans in rheumatoid arthritis--an important clinical cause of false positive results.

The presence of rheumatoid arthritis in patients undergoing 111indium-labelled polymorphonuclear leucocyte scanning represents a source of possible diagnostic confusion. In such patients, the labelled cells frequently accumulate over the caecum and ascending colon, despite the absence of obvious pathology of the large bowel. The aetiology of this effect is unknown.