Rheumatoid arthritis (ra) M06.9

Rheumatoid arthritis is a chronic, inflammatory systemic disease of unknown aetiology, which leads to arthritis, bursitis and tendovaginitis through synovitis and further to the destruction of the affected joints. The characteristic feature of RA is its pronounced clinical variability with broad general symptoms and extra-articular manifestations (e.g. skin symptoms).

Most common rheumatic disease. Familial clustering.

Prevalence: about 0.5-1% of the population. In the older population (> 55 years) the prevalence is 2%.

Women are affected 2-3 times more frequently than men.

The etiology is unknown. A genetic predisposition has been proven (familial clustering; in about 70% of patients the HLA antigen DR4/DRB1 can be detected - in healthy individuals only in about 25%). An autoimmunological inflammatory reaction is induced by unknown trigger mechanisms (environmental factors may play a role), e.g. viral or bacterial antigens, primarily affecting the synovium. T helper lymphocytes, macrophages, B lymphocytes, plasma cells and dendritic cells are involved. Proinflammatory cytokines (IL-1, Il-6, IL-15, TNF-alpha) are formed, as well as autoantibodies (AK against the Fc fragment of immunoglobulin G = rheumatoid factor; AK against cyclic citrullinated peptide = ACPA).

By binding to a receptor, proinflammatory cytokines activate various intracellular signalling pathways which lead to changes in gene expression and can thus trigger the various reactions. Several signal transduction cascades are significant in the pathogenesis of rheumatoid arthritis, namely:

• MAP kinases (mitogen-activated protein kinases)
• SYK (Spleen tyrosine kinase)
• PI3 kinases(phosphoinositide 3-kinases).
• NFκB kinases (nuclear factor 'kappa-light-chain-enhancer' of activated B-cells)
• JAK (Janus kinases).

Furthermore, the conspicuous findings include immune complexes that are detectable in the synovial fluid and are significant in the pathogenesis of vasculitides.

Predominantly occurring in adults (peak incidence: 6-8 decade).

Symmetrical arthritis starting at the hands and feet and later at the large joints near the trunk. Indicated centripetal spread. Patterns of infestation of the hands with regular and high preference for the basic and middle joints. Tendency to spread on the forefeet from lateral to medial.

Skin symptoms:

Rheumatic nodules in about 21-33% of cases. In patients with a positive rheumatoid factor, however, rheumatic nodules may occur significantly more frequently. Sudden, intermittent occurrence of painful nodules with emphasis on the hands, especially the metacarpophalangeal joints and PIPs, is known as "accelerated rheumatic nodulosis".

Nail alterations (27% of patients): Brittle, shiny fingernails with transverse furrows and splintering of the nail matrix are common. Watch glass nails are rare.

Other skin changes (specificity unclear - proven by individual casuistry):

• Fleeting erythema, smooth, tense, atrophic skin over the swollen wrists.
• Sclerodactyl-like changes, possibly dirty-brownish pigmentation over the proximal interphalangeal joints.
• Rheumatoid, neutrophilic dermatitis (very rare disease)
• Interstitial granulomatous dermatitis
• Palisade neutrophilic and granulomatous dermatitis
• Raynaud's symptoms
• Ischemic finger and toe necroses.

Other (rarer) specific organ manifestations are:

• Pericarditis and valvular heart disease
• Commonly COPD, pleuritides
• Kidneys (rare) Membrane glomerulonephritis
• eyes: keratoconjunctivitis
• Vessels: Rheumatoid vasculitis (skin and digital vessels possibly with digital necroses)
• Neurological symptoms: Vasculitis of the vasa nervorum with polyneuropathy.

systemic lupus erythematosus

Vasculitides (e.g. polyarteritis nodosa)

Spondylarthritis

Lyme Arthritis

Rheumatic fever

Arthritis in sarcoidosis

Psoriatic arthritis.

After the ACR/EULAR were described as associated dermatological diseases:

• pyoderma gangraenosum
• Acute febrile neutrophilic dermatosis (Sweet syndrome)
• Sjögren's Syndrome.

According to the ACR/EULAR classification, the following criteria apply to rhematoid arthritis:

Prerequisite:

1. At least one joint with clinical synovitis,
2. which cannot be explained by any other disease.

Evaluation: Points from tables A-D are added up: points of 6 and more are an indicator for a definite RA.

1. Braun MG et al (2004) Development and/or increase of rheumatoid nodules in RA patients following leflunomide therapy. Z Rheumatol 63: 84-87
2. Gause A et al (2003) Rheumatology 2003-part I: research news concerning pathogenesis, epidemiology, diagnosis, and therapy of chronic inflammatory joint diseases. Med Klin (Munich) 98: 523-533
3. Lehnen M et al (2004) New therapeutic options for psoriatic arthritis: TNF inhibitors. German Med Weekly 129: 634-638
4. Margolis DJ et al (2004) Medical conditions associated with venous leg ulcers. Br J Dermatol 150: 267-273
5. Seitz CS (2009) Diagnosis and therapy of dermatological symptoms in patients with rheumatoid arthritis. Act Dermatol 35: 87-89
6. Ziemer M et al (2016) Frequency and classification of cutaneous manifestations in rheumatoid arthritis. J Dtsch Dermatol Ges 14:1237-1247.