Rheumatoid arthritis

Author: Vanessa Ngan, Staff Writer, 2006.

What is rheumatoid arthritis?

Rheumatoid arthritis (RA) is classified as a connective tissue disease. It is a chronic systemic inflammatory disorder that damages the joints of the body. Classic symptoms of rheumatoid arthritis include joint swelling, deformity, pain, weakness, and stiffness of the smaller joints such as those of the hands, wrists, elbows, knees, ankles and feet. These are referred to as the articular manifestations of the disease. When rheumatoid arthritis affects other organs of the body these are known as extra-articular manifestations.

Skin changes of rheumatoid arthritis are considered extra-articular manifestations and can be divided into two types: general cutaneous manifestations and specific cutaneous manifestations.

General cutaneous manifestations

Patients with rheumatoid arthritis may experience a wide array of non-specific skin changes. General signs and symptoms include:

Skin becomes atrophic (thin and wrinkled), making it fragile and easy to bruise
Skin on the back of the hands may become pale or even translucent
Nails may become brittle and split length-wise
The palms become reddened (palmar erythema)

Nonspecific signs of rheumatoid arthritis

Specific cutaneous manifestations

Rheumatoid nodules

Many people with rheumatoid arthritis form subcutaneous nodules. These are lumps that appear on or near the affected joint and are visible just beneath the skin.

Classic rheumatoid nodules
Occur in about 25% of patients Most common extra-articular feature of RA Found in 75% of patients with RA-associated Felty syndrome (in which there are reduced numbers of neutrophils in the blood and the patient has a large spleen) More common in men than women Generally develop later in the RA disease process but can occur before any joint disease Skin coloured, singular or multiple, and range in size from millimetres to centimetres in diameter Most are firm and painless but ones on the soles of the feet or palms may feel uncomfortable Most commonly occur on those areas prone to mild, repetitive irritation, e.g. fingers, heel, forearms, back Rheumatoid nodules have characteristic pathology, but it may sometimes be confused histologically with granuloma annulare. Although nodules are mostly benign, complications such as infection, ulceration, and gangrene can occur following breakdown of skin overlying the nodules Usually no treatment is necessary unless nodules become debilitating, ulcerated, or infected. Surgical removal may be performed.
Rarer causes of rheumatoid nodules
Methotrexate-induced accelerated nodulosis usually occurs as small nodules on fingers, elbows and other joints Rheumatoid nodulosis is a relatively benign rheumatoid variant

Rheumatoid nodules

Neutrophilic dermatoses

Neutrophils are a type of white blood cell (leucocyte). They are present in bacterial infections. They are the prominent cell seen on skin biopsy of some uncommon inflammatory skin diseases known as neutrophilic dermatoses.

Sweet disease and pyoderma gangrenosum are other neutrophilic disorders sometimes seen in association with rheumatoid arthritis.

Rheumatoid neutrophilic dermatitis

Interstitial granulomatous dermatitis

Also known as ‘rheumatoid papules’, interstitial granulomatous dermatitis presents as skin coloured or red papules or plaques often on the trunk. Annular configuration is often noted. Interstitial granulomatous dermatitis is rare. The diagnosis is made when distinctive pathological features are seen on biopsy.

Interstitial granulomatous dermatitis

Rheumatoid vasculitis

Cutaneous vasculitis may be a complication of rheumatoid arthritis and is characterised by dark purplish areas on the skin (purpura) caused by bleeding into the skin from blood vessels damaged by rheumatoid arthritis. Skin changes caused by rheumatoid vasculitis include:

Skin ulcers (usually leg ulcers) may be extensive and painful
Petechiae (purplish spots) or purpura
Nail fold or edge breakdown (digital infarcts)
Gangrene

In addition to skin changes, rheumatoid vasculitis can cause many internal symptoms, including sensory or motor neuropathy (loss of sensation), hepatomegaly (enlarged liver), splenomegaly (enlarged spleen), bowel ulcers, and haematuria (blood in urine).