With CC

Sarcoidosis, formerly called Boeck's sarcoid, is a noncontagious multisystem disorder characterized by epithelioid granular tumors (granulomas) that most frequently affect the lung; more than 90% of cases involve lung or intrathoracic lymph node involvement. Pulmonary sarcoidosis is usually a chronic disorder associated with an intense cellular immune response in the alveolar structures of the lungs. A series of interactions between lymphocytes (primarily responsible for the granuloma formation), macrophage/monocytes (primarily responsible for interstitial fibrosis), epithelioid cells, and giant cells lead to the formation of noncaseating granulomas. The granulomas can lead to fibrosis, which affects the lung's ability to exchange gases. Other recurrent sites include the liver, lymph nodes, bone marrow, skin, and eyes. Sarcoidosis is detected occasionally in the spleen, joints, heart, skeletal muscle, phalangeal bones, parotid glands, and central nervous system (CNS).

About 65% to 70% of the cases of sarcoidosis usually resolve spontaneously within 2 years. Without treatment, however, sarcoidosis can lead to chronic progressive sarcoidosis, which is associated with pulmonary fibrosis, scarring, and progressive pulmonary disease. In such cases, when the heart can no longer pump against the noncompliant fibrotic lungs, cor pulmonale can develop. Other potentially lethal complications are superinfections by organisms such as Aspergillus.

Sarcoidosis is a complex and mysterious disease of unknown origin, although 80% of patients with sarcoidosis have presented with high titers of the Epstein-Barr virus. There is increasing evidence that a triggering agent strikes and stimulates an enhanced cell-mediated immune process at the site of involvement. The triggering agent may be a fungus, an atypical mycobac-terium, pine pollen, or a toxic chemical such as zirconium or beryllium, which can lead to illnesses resembling sarcoidosis. Because there is a slightly higher incidence of sarcoidosis in the same family, the triggering agent may be genetic.

Allelic variation in human leukocyte antigen (HLA)-DRBl increase susceptibility for sarcoido-sis, but familial clustering of this disease may also be due to a shared environment. The much greater frequency in U.S. blacks than in U.S. whites suggests a genetic contribution to etiology. Familial transmission patterns do not follow simple Mendelian rules, making complex transmission combining both genetic and environmental factors most likely.

The disease onset is usually between 20 and 30 years of age or between 45 and 65 years of age and is more frequent among women than men. Frequency is l0 times higher in African Americans than in European Americans; African American women of childbearing age develop sar-coidosis twice as frequently as do African American men.

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