Rheumatology Unit, L. Sacco University Hospital, Milan, Italy
Rheumatoid arthritis (RA) is a chronic inflammatory systemic disorder of unknown aetiology. This disease affects about 0.5-1% of the population worldwide, most commonly middle-aged women. The hallmark of the disease is a synovial inflammation and pannus formation involving small and large joints, often symmetrical in distribution, resulting in pain, stiffness, and loss of function. In fact, in many cases, ongoing synovitis of diarthro-dial joints leads to destruction of articular cartilage and juxtaarticular bone (Harris Jr., 1994).
Numerous extra-articular manifestations occur, particularly in male patients who are anti-nuclear antibodies (ANA) and rheumatoid factor (RF) positive. Extra-articular manifestations can be detected in almost any organ system, causing considerable disease-related morbidity and interference with quality of life (Cimmino et al., 2000).
The most widely recognized skin lesion is the rheumatoid nodule. A variety of skin manifestations can be observed either non-specific or related to the disease itself and/or to the commonly used drugs (Sayah and English, 2005).
The prevalence of RA is approximately 0.5-1% in diverse populations worldwide (Alamanos and
Piercarlo Sarzi-Puttini, MD Rheumatology Unit, - University Hospital L. Sacco Via GB Grassi, 74 20157 Milan - Italy E-mail address: [email protected] (P. Sarzi-Puttini).
Drosos, 2005). However, an unusually high prevalence of the disease has been reported in certain North American Indian tribes, while the disease is rare in rural Africans and rural and urban Chinese. RA affects women more often than men. The annual incidence is approximately 0.2-0.4 per 1000 in females and 0.1-0.2 per 1000 in males (Alamanos and Drosos, 2005).
The aetiology of RA remains elusive, although it appears that genetic, infectious, environmental, and hormonal factors are all involved in complex, interrelated ways.
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