Rheumatoid arthritis (RA) is an autoimmune disorder where the immune system mistakenly attacks its own tissues, primarily targeting the joints and causing inflammation, stiffness, and pain. While joint symptoms are the typical presentation, RA is a systemic disease, meaning it affects the entire body. The inflammation can extend to numerous other organs and tissues, leading to extra-articular manifestations (EAMs). These unusual symptoms can be subtle or severe, sometimes appearing before joint pain begins, reflecting widespread immune dysfunction.
Manifestations Affecting the Eyes and Mucous Membranes
The eyes and mouth are frequent targets of RA-related inflammation, often resulting in severe dryness. When this occurs alongside RA, it is known as secondary Sjögren’s Syndrome, affecting the moisture-producing tear and salivary glands. Damage to these glands causes chronic dry eyes and a dry mouth, which increases the risk of dental decay and oral infections.
Beyond dryness, RA can directly inflame the eye’s outer structures, leading to conditions like episcleritis and scleritis. Episcleritis involves inflammation of the episclera, the thin layer covering the white part of the eye, presenting as a pink-red patch. This condition is usually self-limiting, often causing only mild discomfort.
Scleritis is a more serious inflammation of the sclera, the thick, white protective layer of the eye. This condition is often intensely painful and signals aggressive systemic inflammation, sometimes indicating underlying vasculitis. Severe scleritis can lead to vision loss or corneal perforation, making immediate ophthalmologic evaluation and aggressive systemic treatment necessary.
Changes to Skin and Subcutaneous Tissue
The skin and subcutaneous tissue can exhibit visible signs of RA’s systemic inflammation. The most common extra-articular feature is the development of rheumatoid nodules, which are firm, painless lumps that form beneath the skin. These nodules occur most frequently on areas subjected to pressure, such as the elbows, forearms, hands, and the Achilles tendon.
Their size varies widely. While generally harmless, they can occasionally break down, leading to ulceration, infection, or rupture. Their presence often correlates with more severe, long-standing disease and is more common in patients who test positive for rheumatoid factor.
A less common but more severe manifestation is rheumatoid vasculitis, which involves inflammation of the small and medium-sized blood vessels. On the skin, this condition can cause small rashes, tiny spots of bleeding under the nails (splinter hemorrhages), or painful ulcers, particularly on the lower legs. Vasculitis is serious because it indicates widespread inflammation that can restrict blood flow to organs, requiring prompt and aggressive medical intervention.
Impact on Major Internal Organ Systems
The inflammatory process of RA can affect major internal organs, most commonly the lungs and heart. In the lungs, RA can cause interstitial lung disease (ILD), where chronic inflammation leads to scarring (fibrosis) of the tissue. This scarring makes the lungs stiff and causes symptoms like a persistent dry cough and progressive shortness of breath. ILD is a significant contributor to mortality in RA patients and can even precede joint symptoms.
Other pulmonary complications include pleurisy, inflammation of the pleura, the membrane surrounding the lungs. Pleurisy may result in a pleural effusion (fluid accumulation), which can cause chest pain. Rheumatoid nodules can also form within the lung tissue, typically remaining asymptomatic but requiring monitoring.
Within the cardiovascular system, RA inflammation affects the heart and blood vessels. Pericarditis, inflammation of the sac surrounding the heart, may occur and cause chest pain. Chronic systemic inflammation accelerates atherosclerosis, the hardening and narrowing of the arteries. This significantly increases the risk of heart attacks and strokes in people with RA.
Neurological and Nerve-Related Symptoms
Rheumatoid arthritis can also impact the nervous system, leading to symptoms distinct from typical joint pain. Peripheral neuropathy involves damage to the nerves outside the brain and spinal cord, resulting in numbness, tingling, or a burning sensation. This often affects the hands and feet in a glove-and-stocking pattern.
This nerve damage can be caused by systemic inflammation or by compression from surrounding swollen tissues. A common example is Carpal Tunnel Syndrome, where inflamed tendons and joint swelling squeeze the median nerve in the wrist. This causes pain and a pins-and-needles sensation in the fingers and hand.
Similar nerve compression can occur in the ankle, leading to Tarsal Tunnel Syndrome, which causes pain and tingling in the foot. While these issues are not life-threatening, they can significantly contribute to disability and functional impairment.