ABSTRACT
Sarcoidosis is a multisystem condition characterized by the formation and infiltration of noncaseating granulomata to affected organs. It can involve the eyes, skin, brain, heart, bone, or liver but the most common organ affected is the lung. Given that sarcoidosis is in some individuals a selflimiting disease of short duration and that in others it progresses to become a chronic disease, estimation of incidence and prevalence is challenging. Notwithstanding this, much of the published data suggest an annual incidence in the United States and Western Europe of between 5 and 10 per 100,000 and a point prevalence of approximately twice this figure. Over the past 30 years, there has been no suggestion of a change in the incidence of the disease. There is a bimodal age distribution, with the peak age of incidence (70%) between ages 25 and 40 and a second smaller peak reported in Europe and Japan largely comprising females between the ages of 50 and 60. It very rarely presents in childhood or in the elderly. Sarcoidosis is more frequently observed in females, with most recent estimates suggesting that the gender ratio is 1.20:1.75 (M:F). There is also a clear racial predisposition, with the disease much more prevalent in African and Afro-Caribbean individuals (an almost 10fold increase). In this group, the disease is more frequently systemic and more severe and follows a more chronic course. Higher incidence rates have also been found in Northern Europeans, but the disease is uncommon in Japan. Although usually sporadic, sarcoidosis is familial in up to 9.6% of cases. A pattern of recessive inheritance with incomplete penetrance has been proposed and there is an 80 times increased risk in monozygotic twins.
