Subcutaneous nodules seen in 20-30% of rheumatoid arthritis patients. they may arise anywhere on the body, but are most frequently found over the bony prominences. the nodules are characterized histologically by dense areas of fibrinoid necrosis with basophilic streaks and granules, surrounded by a palisade of cells, mainly fibroblasts and histiocytes.

A rheumatoid nodule is a lump of tissue, or an area of swelling, that appears on the exterior of the skin usually around the olecranon (tip of the elbow) or the interphalangeal joints (finger knuckles), but can appear in other areas. There are four different types of rheumatoid nodules: subcutaneous rheumatoid nodules, cardiac nodules, pulmonary nodules, and central nervous systems nodules...