Confusable diagnoses · PANCE / PANRE

Tuberculosis vs Sarcoidosis

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Tuberculosis and Sarcoidosis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.

Tuberculosis vs Sarcoidosis at a glance

  • Tuberculosis: Mycobacterium tuberculosis infection — active disease or asymptomatic latent infection (LTBI).
  • Sarcoidosis: Multisystem non-caseating granulomatous disease most commonly involving lungs and lymph nodes.

Try two board-style questions on Tuberculosis vs Sarcoidosis

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Question 1PulmonaryMedium
A 38-year-old recent immigrant from Southeast Asia presents with three months of productive cough, night sweats, low-grade fevers, and a 6 kg weight loss. He is HIV-negative. Chest radiograph shows a right upper lobe cavitary infiltrate. Sputum acid-fast bacilli smear is positive and nucleic acid amplification testing confirms Mycobacterium tuberculosis without detected rifampin resistance. Which of the following is the most appropriate initial regimen?
  • ABedaquiline, linezolid, and pretomanid
  • BRifampin and isoniazid
  • CIsoniazid monotherapy
  • DRifampin, isoniazid, pyrazinamide, and ethambutol
Reveal answer & full explanation
Correct answer: D — Rifampin, isoniazid, pyrazinamide, and ethambutol
  • ABedaquiline, linezolid, and pretomanid
  • BRifampin and isoniazid
  • CIsoniazid monotherapy
  • DRifampin, isoniazid, pyrazinamide, and ethambutol✓

Why Rifampin, isoniazid, pyrazinamide, and ethambutol is correct

  • Active drug-susceptible pulmonary tuberculosis requires the standard first-line regimen: a 2-month intensive phase of rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE), followed by a 4-month continuation phase of rifampin and isoniazid.
  • Four drugs are used initially to prevent emergence of resistance and rapidly reduce bacillary load.

Why the others are wrong

  • Bedaquiline, linezolid, and pretomanid — the BPaL regimen is reserved for multidrug- or extensively drug-resistant TB, not drug-susceptible disease (wrong-resistance-tier).
  • Rifampin and isoniazid — this two-drug combination is the continuation phase used after the intensive phase, inadequate as initial therapy (right-drugs-wrong-phase).
  • Isoniazid monotherapy — the regimen for latent TB infection without active disease; using it here would select for resistance (confused-with latent TB).

Additional high-yield points

  • Directly observed therapy is recommended to ensure adherence.
Question 2PulmonaryMedium
A 36-year-old African American female has bilateral hilar lymphadenopathy on chest X-ray, mild dyspnea, and erythema nodosum. Serum angiotensin-converting enzyme (ACE) level is elevated and serum calcium is 11.2 mg/dL. Which of the following is the most likely diagnosis?
  • ALymphoma
  • BSarcoidosis
  • CHistoplasmosis
  • DTuberculosis
Reveal answer & full explanation
Correct answer: B — Sarcoidosis
  • ALymphoma
  • BSarcoidosis✓
  • CHistoplasmosis
  • DTuberculosis

Why Sarcoidosis is correct

  • Sarcoidosis is a noncaseating granulomatous disease most common in young adults, especially African American women
  • The combination of bilateral hilar lymphadenopathy, pulmonary symptoms, and erythema nodosum in this demographic is classic for sarcoidosis
  • Hypercalcemia results from granuloma 1-alpha-hydroxylase activity converting 25-OH vitamin D to active 1,25-OH vitamin D
  • Serum ACE elevation is supportive but nonspecific; it can rise in other granulomatous and lung diseases and cannot confirm the diagnosis on its own
  • When the presentation is uncertain, tissue biopsy showing noncaseating granulomas (with exclusion of infection and malignancy) is required to confirm sarcoidosis
  • Note: Löfgren syndrome is the classic acute triad of bilateral hilar lymphadenopathy, erythema nodosum, and ankle arthritis/periarthritis (often with fever); bilateral hilar adenopathy plus erythema nodosum alone does not complete the triad

Why the others are wrong

  • Lymphoma — can cause mediastinal/hilar adenopathy and hypercalcemia, but the adenopathy is typically asymmetric/bulky and erythema nodosum plus elevated ACE point away from it (confused-with sarcoidosis on the adenopathy finding)
  • Histoplasmosis — endemic fungal infection that can produce hilar adenopathy and erythema nodosum, but granulomas are caseating and it lacks the hypercalcemia/elevated-ACE pattern seen here (right-concept-wrong-setting, missing the endemic exposure history)
  • Tuberculosis — granulomatous disease, but classically forms caseating granulomas with unilateral/asymmetric adenopathy and constitutional symptoms rather than symmetric bilateral hilar adenopathy with hypercalcemia (confused-with sarcoidosis on the granuloma finding)

Additional high-yield points

  • Treatment: observation if mild; corticosteroids for end-organ involvement (lung, eye, heart, CNS, kidney)
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Side-by-side comparison

FeatureTuberculosisSarcoidosis
At a glanceMycobacterium tuberculosis infection — active disease or asymptomatic latent infection (LTBI).Multisystem non-caseating granulomatous disease most commonly involving lungs and lymph nodes.
Classic presentationApical/posterior upper lobe or superior segment of lower lobe cavitary disease (reactivation); hilar lymphadenopathy + middle/lower lobe infiltrate (primary); miliary nodules (2-3 mm) on CXR (disseminated).; LTBI: asymptomatic by definition; Active pulmonary TB: chronic cough >3 weeks (productive, may be hemoptysis), drenching night…Bilateral hilar lymphadenopathy on CXR in young African American or northern European patient; Löfgren triad; lupus pernio; bell's-like facial palsy.; Pulmonary: dry cough, dyspnea, chest discomfort (~90% have lung involvement at some point); Constitutional: fatigue, fever, weight loss, night sweats; Skin: erythema nodosum, lupus pernio…
Workup / key labsLTBI: positive TST (induration ≥5/10/15 mm cutoff based on risk) or positive IGRA + no active disease on imaging/clinical evaluation. Active TB: clinical findings + positive AFB smear/NAAT/culture from respiratory or other site.; LTBI: tuberculin skin test (TST/PPD) OR interferon-gamma release assay (IGRA — QuantiFERON, T-SPOT); neither…Clinical/radiographic presentation + biopsy showing non-caseating granulomas + exclusion of alternative causes. Löfgren syndrome and asymptomatic Stage I CXR in a young patient may be diagnosed clinically without biopsy.; ACE level — elevated in ~60%, neither sensitive nor specific (poor diagnostic value); CBC (lymphopenia, mild…
ImagingCXR — primary: hilar adenopathy, middle/lower infiltrate, Ghon complex; reactivation: apical/posterior cavitary lesions; miliary: 2-3 mm nodules diffuse; CT chest if CXR equivocal or to characterize disease; MRI brain/spine if neurologic/spinal TB suspectedChest radiograph — Scadding stage (0-IV): 0 normal; I bilateral hilar adenopathy; II hilar adenopathy + parenchymal disease; III parenchymal only; IV fibrosis; HRCT chest — perilymphatic micronodular pattern (along bronchovascular bundles, fissures, subpleural), bilateral symmetric hilar/mediastinal adenopathy; PET/CT — identifies…
First-line treatmentLTBI (CDC 2020 preferred shorter regimens): isoniazid + rifapentine weekly × 12 weeks (3HP, by DOT or self-administered); OR rifampin daily × 4 months (4R); OR isoniazid + rifampin daily × 3 months (3HR); LTBI alternative: isoniazid daily × 6 or 9 months (older standard; longer, more hepatotoxicity); Active drug-susceptible TB (RIPE × 2…Many patients require no treatment — spontaneous remission in ~50% within 2-5 years; Indications for systemic therapy: progressive pulmonary disease, symptomatic Stage II/III, cardiac involvement, neurosarcoidosis, ocular disease unresponsive to topical therapy, hypercalcemia, severe constitutional symptoms; Corticosteroids —…

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Full outlines

Tuberculosis (Active and Latent) Sarcoidosis All 514 diagnoses

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.