As sarcoidosis is now more widely recognized and with increased rigor in its diagnosis, previous, older characterizations of the disease prevalence and incidence may be incorrect. Based on more recent work, the disease seems to vary widely throughout the world in terms of incidence. That said, it remains highly prevalent in African Americans, almost three times the annual incidence of white Americans (35.5 cases per 100,000, as compared with 10.9 per 100,000) [4]. The lifetime risk of sarcoidosis in African Americans in the United States is quoted at approximately 2.4 %, compared with a lifetime risk of 0.85 % in Caucasians [4]. It has also been well characterized in many other countries including Japan (incidence of about 2 cases per 100,000 people) [5], which has established the well-known Japanese Ministry of Health criteria for diagnosis of the disease. The highest reported incidence occurs in northern European countries and is quoted at 5–40 cases per 100,000 people [5]. Overall, the disease prevalence is estimated at 20 per 100,000 [6].

For most cases, sarcoidosis develops before middle age, usually before age 50, with peak incidence in early adulthood, ages 20–39. In Japan, the peak incidence is in the third decade, while in Americans, the incidence is later in life, usually in the fourth decade. Americans afflicted with the disease are also more likely to have chronic active disease states and are more likely to succumb to the disease [7]. Interestingly, in Scandinavia, there are two peaks for age of onset: one at 25–29 years and the other at 65–69 years of age [8]. While both sexes are affected, in all countries women seem to be more commonly affected [9]. Overall, sarcoidosis presents from 10 to 40 years of age in 70–90 % of cases. More than half of all cases are detected incidentally by radiography prior to symptoms [7].

While socioeconomic status doesn’t clearly affect incidence, those of lower socioeconomic status are more likely to present later in the disease process due to the barriers of low income, lack of access to medical providers, and lower educational level. Furthermore, if adjusted for race, ethnicity, age, or gender, this higher degree of severity in this socioeconomic status persists [10].

Sarcoidosis can involve nearly any organ system, but is most often found involving the pulmonary system in more than 90 % of the cases reported. Up to 30 % of patients afflicted with the disease have extra-thoracic manifestations [7]. In addition to pulmonary involvement, it most commonly affects the skin, and eyes. Cardiac involvement is variable, but is a major cause of morbidity and mortality.