Table 2.
Highlights the characteristic differentiating features in patients with common infectious etiologies which can mimic sarcoidosis.
| Features | Sarcoidosis | Mycobacterium tuberculosis | Histoplasmosis | |
|---|---|---|---|---|
| A |
Lab findings 1. ACE level 2. Abnormal calcium metabolism 3. Kveim-Siltzbach test 4. Mantoux test 5. Other diagnostic tests |
Elevated ACE (50–80%) (19–21) Elevated vitamin D Hypercalcemia Hypercalciuria (22) Positive in 60% (23) Anergic; Negative in 90% (24) |
Elevated ACE in 9% (22, 25) Hypovitaminosis D Hypercalcemia rare but can be seen in MTB IRD cases (26) Negative Positive in 65–94% (27, 28) PCR MTB |
Elevated in 25% (29, 30) Hypercalcemia rare but can be seen (31) Negative Negative Histoplasma antigen in urine (sensitivity 93–100%) (Gold standard test) and serum (32) - PCR assays for the Hcp 100 gene - Histoplasmin sensitivity skin test |
| B | BAL findings | - CD4/CD8 ratio >3.5 (33) - Elevated ACE (34, 35) |
BAL AFB smear (sensitivity 38.1%) BAL culture (sensitivity 74.5%) (35, 36) Elevated CD4+/CD8+ ratio (37) |
Histoplasmosis Antigen in BAL (38) |
| C | Histopathology | Non-caseating granulomas | Caseating granulomas - AFB+ bacilli - Isolation of MTB |
-Non-caseating granulomas - Isolation of H. capsulatum from tissue specimens (gold standard) - methenamine silver or PAS stains revealing narrow-based budding yeasts |
| D | 1. Radiological Hilar and mediastinal LAD 2. EBUS |
Bilateral Hilar LAD when present is symmetrical Nodules Reticulonodular opacities Cavitation rare Granular appearance in lymph nodes -highest specificity (99.3%) for the diagnosis of sarcoidosis (39). |
Asymmetrical, unilateral Upper-lobe infiltrates with cavitation, tree-in-bud, macro-nodular infiltrates (3). Cavitation is more common (9) Heterogeneous echotexture (53.4% P < 0.001) and coagulation necrosis (26.1% P < 0.001) (11) |
Asymmetrical, unilateral (40) Fibrosing mediastinitis Reticulonodular opacities Cavitation is rare (41) Non-specific |
| E | Treatment | Immunosuppressant like corticosteroids | ATT | Itraconazole, AMB Streptomycin |
AFB, Acid Fast Bacilli; ATT, Anti-Tuberculosis Treatment; AMB, Amphotericin B; MTB, Mycobacterium tuberculosis; LAD, Lymphadenopathy; PCR, Polymerase Chain Reaction; MTB-IRD, Mycobacterium tuberculosis Immune Reconstitution Disease.