Difference between Sarcoidosis and Tuberculosis

Sarcoidosis and tuberculosis are both granulomatous disease with similar constitutional symptoms, respiratory symptoms and multiple organ involvement with hilar and mediastinal lymph node involvement. Hence, the diagnosis of one from the other may pose significant difficulties.

tb vs sarcoidosis

Sarcoidosis vs Tuberculosis (TB)

IFN-gamma release assays (IGRA)Tuberculosis can be reliably excluded if both Mantoux test and IGRA is negative.

FeaturesSarcoidosisTuberculosis
EpidemiologyAfrican American and American populations

Scandinavia

TB endemic regions – Subsaharan Africa, Asia

Homeless, prison populations, drug abuse

Increased susceptibilityHLA association

Family history (5 fold risk)

Defects in cell mediated immunity (CMI), HIV
Clinical differences
Skin lesionsCommonRare (lupus vulgaris)
Lupus pernioDiagnosticNone
Erythema nodosumCommonRare
Eye diseaseCommonRare
Pleural diseaseVery rareCommon
Cranial nerve VII palsyCommonRare
Pattern of organ involvementUveal tract, salivary and lacrimal glands, heart and skeletal muscles, liver and spleen and small bones of hand and feet are commonly involved in sarcoidosis but are rarely seen in tuberculosis.Adrenal glands may be involved in caseating tuberculosis but almost never in sarcoidosis.

Involvement of small intestine is common in TB but rare in sarcoidosis.

Marked constitutional symptoms like night sweats and weight loss12%More suggestive of tuberculosis
Lab investigations
HypercalcemiaCan occurVery rare
Serum ACEElevated in 87%Elevated in 4%
Mantoux testAnergic

Negative in 90%

Positive in 65-94%
Kveim-Siltzbach testPositive in 60%Negative
Bronchoalveolar lavage (BAL) lymphocytes

BAL CD4/CD8 ration > 3.5

Very commonCommon
Histology/microscopyDefined non-caseating granulomaCaseating granulomas

‘Acid fast’ positive bacilli

Isolation of mycobacterium tuberculosisNone or incidence similar to control groupsPositive
Radiological differences
Hilar and mediastinal lymphadenopathySymmetrical and BilateralAsymmetrical and usually unilateral
OtherDiffuse or micronodular interstitial infiltrates

Upper lobe fibrosis

Rarely diffuse alveolitis or cavitating masses

Necrosis common

Upper-lobe infiltrates with cavitation, tree-in-bud, macro-nodular infiltrates.

Cavitation is more common in TB.

Treatment
Immunosuppresives like steroidsAntitubercular therapy including Isoniazid, Rifampicin, Ethambutol, Pyarzinamide

References:

  1. Sarcoidosis edited by Donald N Mitchell, Athol Wells, Stephen G Spiro, David R Moller
  2. Oxford Textbook of Medicine Vol. 1
  3. Challenging cases in pulmonology by Massoud Mahmoudi