Characteristic and specific histological findings in rheumatoid pleurisy.

The histological findings in rheumatoid pleuritis (RP), as seen in thoracoscopical biopsies, are found to be: A slightly inflamed stroma with a wave-like surface due to vessel-containing flattened papillae. The surface is covered by layers of pseudostratified epithelioid cells and scattered multinucleated giant cells, layers that easily detach as membranes, leaving the stroma surface "naked". These findings, in combination with the absence of mesothelial cell covering, are viewed as characteristic and specific, as based on a blind review of 17 pleural biopsies from RP patients and 14 biopsies from a control group.