Sarcoidosis

Key Features

Essentials of Diagnosis

• Symptoms related to

  • Lung

  • Skin

  • Eyes

  • Peripheral nerves

  • Liver

  • Kidney

  • Heart

  • Other tissues

• Demonstration of noncaseating granulomas in biopsy specimen

• Exclusion of other granulomatous disorders

General Considerations

• A systemic disease of unknown etiology

• Granulomatous inflammation of the lungs is present in 90% of cases

Demographics

• Highest incidence in North American blacks and northern European whites

• Among blacks, women are more frequently affected than men

• Disease onset is usually in the third or fourth decade

Clinical Findings

Symptoms and Signs

• Malaise, fever, and insidious dyspnea

• Symptoms from erythema nodosum, iritis, peripheral neuropathy, arthritis or cardiomyopathy may also prompt initial evaluation

• Some patients are asymptomatic, and diagnosis is made after abnormal findings are noted on chest radiograph

• Crackles are uncommon on chest examination

• Parotid gland enlargement, hepatosplenomegaly, and lymphadenopathy may be noted

• Myocardial sarcoidosis is found in 5% of patients and can lead to

  • Restrictive cardiomyopathy

  • Cardiac dysrhythmias

  • Conduction disturbances

Differential Diagnosis

• Other granulomatous diseases must be excluded

  • Tuberculosis

  • Histoplasmosis

  • Coccidioidomycosis

• Lymphoma (including lymphocytic interstitial pneumonitis)

• Idiopathic pulmonary fibrosis

• Pneumoconiosis (especially berylliosis)

• Syphilis

Diagnosis

Laboratory Tests

• Leukopenia

• Elevation of erythrocyte sedimentation rate

• Hypercalcemia in 5%, hypercalciuria in 20%

• Angiotensin-converting enzyme (ACE) levels

  • Commonly elevated in active disease

  • Neither sensitive nor specific enough to be of diagnostic value

• Physiologic testing may reveal evidence of airflow obstruction, but restrictive changes with decreased lung volumes and diffusing capacity are more common

• Skin test anergy is present in 70%

Imaging Studies

• Radiographic findings are variable

  • Stage I: hilar adenopathy alone

  • Stage II: hilar adenopathy with parenchymal involvement

  • Stage III: parenchymal involvement alone

  • Stage IV: advanced fibrotic changes principally in the upper lobes

• Parenchymal involvement usually manifests as diffuse reticular infiltrates, but focal infiltrates, acinar shadows, nodules, and rare cavitation are seen

• Pleural effusion occurs in < 10% of patients

Diagnostic Procedures

• ECG may show conduction disturbances and dysrhythmias

• Biopsy demonstrating noncaseating granulomas is required for diagnosis

  • Easily accessible biopsy sites include lymph nodes, skin lesions, and salivary glands

  • Transbronchial biopsy has a yield of 75–90%

  • Some experts believe biopsy is unnecessary in stage I disease with a presentation highly suggestive of sarcoidosis

• Bronchoalveolar lavage is usually characterized by an increase in lymphocytes with a high CD4/CD8 ratio; this may be used to follow disease activity, but not for diagnosis

Treatment

Medications

• Corticosteroids (eg, oral prednisone, 0.5–1.0 mg/kg/day) are indicated for

  • Constitutional symptoms

  • Hypercalcemia

  • Iritis

  • Uveitis

  • Arthritis

  • CNS involvement

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