Sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder, commonly affecting young adults and usually presenting with:

• Bilateral hilar lymphadenopathy
• Pulmonary infiltration
• Skin lesions
• Eye lesions

Diagnosis is confirmed on the histological evidence of widespread, non-caseating, epithelioid granulomas in more than one organ

Epidemiology:

• Unknown aetiology
• 19 per 100,000 in the UK
• Peak incidence is in the 30s and 40s
• Females > males

Clinical features:

• Respiratory symptoms
• Abnormalities found on CXR (e.g. bilateral hilar lymphadenopathy)
• Fatigue (~5%)
• Weight loss (~5%)
• Peripheral lymphadenopathy (~5%)
• Fever (~4%)

Bilateral hilar lymphadenopathy:

• A characteristic feature of sarcoidosis
• Often asymptomatic and only detected by a routine CXR
• Evidence from CT scanning shows that the lung parenchyma is nearly always involved

The differential diagnosis of bilateral hilar lymphadenopathy includes:

• Sarcoidosis
• Lymphoma (although it is rare for this to only affect the hilar lymph nodes)
• Pulmonary TB
• Carcinoma of the bronchus (with malignant spread to the contralateral hilar lymph nodes)

Pulmonary infiltration:

• This type of sarcoidosis may be progressive and may lead to:
• Increasing effort dyspnoea
• Cor pulmonale
• Death

• Pulmonary function tests show a typical restrictive lung defect

Extrapulmonary manifestations of sarcoidosis:

Skin lesions:

• Lupus pernio (a chilblain-like lesion) is seen in 10% of cases
• Erythema nodosum (sarcoidosis is the most common cause)

Ocular and associated effects:

• Anterior uveitis:
• Misting of vision
• Painful eye
• Red eye

• Posterior uveitis:
• Progressive loss of vision

Metabolic manifestations:

• Hypercalcaemia in 10% of established cases:
• Caused by the high circulating concentration of 1,25-dihydroxycholecalciferol
• This is because there is a high concentration of 1α-hydroxylase in sarcoid macrophages in the lung
• Hyperuricaemia
• These 2 factors can lead to the formation of renal calculi

CNS:

• Involvement is rare (<2%)
• Can cause severe neurological disease

Hepatosplenomegaly

Cardiac involvement:

• Occurs in ~3% of patients
• Can cause:
• Ventricular dysrhythmias
• Conduction defects
• Cardiomyopathy
• CCF

Investigations:

Imaging:

• CXR
• CT

Blood tests:

• FBC (there is a mild normochromic normocytic anaemia)
• ESR (raised)
• Biochemistry (hypercalcaemia and hypergammaglobulinaemia)

Transbronchial biopsy:

• Is the most useful investigation
• This test provides histological evidence of a granuloma in ~50% of patients with clinically extrapulmonary sarcoidosis in whom the CXR is normal

Serum level of ACE:

Is 2 SDs above normal in 75% of patients with untreated sarcoidosis

Lung function tests:

Show a restrictive lung defect with pulmonary infiltration

Decreased:

TLC

FEV₁

FVC

Gas transfer

Treatment:

• If the disease is not improving spontaneously within 6 months of diagnosis, treatment should be started
• Prednisolone 30mg daily for 6 weeks, reducing to alternate-day treatment with prednisolone 15mg for 6-12 months

Prognosis:

• The disease is fatal in <5% of patients in the UK
• Most deaths are from respiratory failure and cor pulmonale
• The disease remits within 2 years in over:
• 65% of patients with hilar lymphadenopathy alone
• 50% of patients with hilar lymphadenopathy plus CXR evidence of pulmonary infiltration
• 30% of patients with X-ray evidence of infiltration without any demonstrable lymphadenopathy