Marked thrombocytosis with chromosomal abnormalities in a patient with rheumatoid arthritis.

An 80 year-old Japanese woman with rheumatoid arthritis (RA), complicated with thrombocytosis is described. Mild to moderate thrombocytosis is commonly observed in patients with RA, but she had marked thrombocytosis of over 1000 x 10(3)/mm3 and monosomy 22 with marker chromosome. This case suggests that thrombocytosis unusual with disease activity of RA might occur, and that careful evaluation of the thrombocytosis is required.