As part of the rheumatoid process, firm, non-tender, subcutaneous nodules develop in about 25 percent of rheumatoid
arthritis patients. These are commonly found at pressure points like the elbow, back of the forearm, and metacarpophalangeal joint. Nodules usually occur in chronic active cases of rheumatoid arthritis, and are commonly associated with more joint deformity and serious extra-articular manifestations including lungs, eyes, and blood vessels.