Sarcoidosis is a multisystem granulomatous disorder of unknown etiology affecting young and middle-aged adults. It is characterized histologically by epithelioid tubercles involving various organs or tissues, with symptoms dependent on the site and degree of involvement.
Sarcoidosis affects men and women of all races and ages. The condition usually presents in adults younger than 40 years, most frequently between 20 and 29 years of age. It is slightly more predominant in women than in men, with an incidence of 6.3 and 5.9 cases per 100,000 person-years, respectively. The lifetime risk of sarcoidosis for U.S. whites is estimated at 0.85 percent compared with 2.4 percent in U.S. blacks. Sarcoidosis is most prevalent in Swedes, Danes, and U.S. blacks. Mortality from sarcoidosis, usually caused by respiratory failure, approaches 1 to 5 percent. Because most patients with sarcoidosis do not die of the disease, the medical challenge is to help them live well with their symptoms (Schiff, 2004).
Patients commonly present with bilateral hilar lymphadenopathy, pulmonary infiltrates, and ocular and skin lesions. The heart, liver, spleen, salivary glands, muscles, bones, kidneys, and central nervous system also may be involved (Schiff, 2004). Sarcoidosis may affect any organ, although the lungs are involved in up to 95% of patients. Other organ systems commonly affected include the skin, eyes, and lymphoreticular system. Estimates of organ involvement are confounded by the method of discovery, referral bias, and the sensitivity of diagnostic modalities. Why different organs are differentially affected in various individuals is unclear. When sarcoidosis is suspected in extra-pulmonary organs, chest imaging or random transbronchial biopsy may be helpful to help confirm the diagnosis (Culver, et al, 2005). The characteristic histopathologic findings are multiple noncaseating epithelioid granulomas, with little or no necrosis, which may resolve completely or proceed to fibrosis (Robbins, 1998).
The cause is unknown. A single provoking agent or a disordered defense reaction triggered by a variety of insults may be responsible; genetic factors may be important. Symptoms may be absent, slight, or severe and depend on the site of involvement. Impairment of function may be due to the active granulomatous disease or to secondary fibrsosis. Fever, weight loss, and arthralgias may be initial manifestations. Persistent fever is usually common with hepatic involvement (Robbins, 1998).
Laboratory findings show that leukopenia is frequently present. Elevated serum uric acid is not uncommon, but gout is rare. Serum alkaline phosphatase may be elevated as a result of hepatic involvement (Murray, et al, 2000). Serial measurements of pulmonary function are a guide to treatment and to the course of the disease.
Diagnosis is based on clinicoradiologic findings plus histologic evidence of noncaseating epithelioid granulomas, and exclusion of other granulomatous diseases. A clinical diagnosis may be made in asymptomatic patients with typical chest x-ray finding. Tissue biopsy, with microbiologic as well as histologic examination, is essential if symptoms are present and corticosteroid therapy seems indicated (Robbins, 1998). Prognosis correlates with mode of onset, host characteristics, initial clinical course, and extent of disease (Schiff, 2004).
The optimal management of sarcoidosis has not been well defined. Evaluation of treatment is difficult since spontaneous improvement or clearing is common. Massive hilar adenopathy and extensive infiltrates may disappear in a few months or years (Robbins, 1998). Gradual pulmonary fibrosis, leading to pulmonary insufficiency, pulmonary hypertension, and cor pulmonale, is the leading cause of disability and death.
Corticosteroid therapy is indicated for suppression of the active inflammatory reaction and for troublesome or disabling symptoms, such as dyspnea, severe arthralgia, or fever. It should be started promptly if active ocular disease, respiratory failure, hepatic insufficiency, cardiac arrhythmia, CNS involvement, or hypercalcemia is present (Robbins, 1998). Serious complications of corticosteroid therapy have been infrequent.
Although corticosteroids remain the mainstay of treatment, there is little evidence for the optimal initiation, dosage, or duration of therapy. Topical steroids may be considered for treatment of anterior uveitis and skin lesions. Systemic steroids are indicated for treatment of cardiac, nervous system, severe ocular, and symptomatic or progressive pulmonary involvement. There is little evidence for the efficacy of inhaled steroids (Schiff, 2004).
Cytotoxic agents and immunomodulators usually are reserved for treatment of complex or refractory disease. Of these agents, methotrexate is used more frequently because of its safety profile and possible steroid-sparing effects. Antimalarial agents are used frequently for skin lesions, and they have limited success in the treatment of pulmonary disease. Lung and cardiac transplantation is reserved for end-stage disease. Monitoring for symptoms of drug toxicity is essential, and prevention of osteoporosis must be addressed in patients taking long-term oral corticosteroids. It is not known if current therapy alters disease progression (Schiff, 2004).
The aim of the treatment is to prevent progressive tissue damage and irreversible fibrosis, but no available therapeutic agents have been shown to accomplish this in the lungs (Robbins, 1998). Symptomatic hilar or peripheral adenopathy needs no treatment.
REFERENCES
Culver, D.A., Aladesanmi, O., & Kavuru, M.S. (2005). Sarcoidosis, Retrieved
from: http://www.clevelandclinicmeded.com/diseasemanagement/pulmonary/sarcoid/sarcoid.htm
Murray, R.K., Granner, D.K., Mayes, P.A. & Rodwell, V.W. (2000). Harper’s
Biochemistry 25th Edition, McGraw-Hill.
Robbins, S.L. (1998). Pathologic Basis of Disease, W.B.Saunders Company.
Schiff, K.R. (2004). Sarcoidosis (A Broader Understanding of Diagnosis, Types
and Medical Treatment to be Administered). American Family Physician.
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