A 52-year-old farmer from Punjab presents with progressive dyspnea and constitutional symptoms. Chest X-ray shows bilateral hilar lymphadenopathy with non-caseating granulomas on biopsy. Serum calcium is elevated (11.2 mg/dL) and serum ACE level is raised. Which single feature most reliably distinguishes this patient's condition (sarcoidosis) from chronic berylliosis, which also presents with non-caseating granulomas?

Explanation

## Distinguishing Sarcoidosis from Chronic Berylliosis **Key Point:** While both sarcoidosis and chronic berylliosis present with non-caseating granulomas, the **beryllium lymphocyte proliferation test (BeLPT)** is the gold-standard discriminatory test. A positive BeLPT confirms beryllium sensitization and chronic berylliosis; a negative BeLPT supports sarcoidosis. ### Comparison Table | Feature | Sarcoidosis | Chronic Berylliosis | | --- | --- | --- | | **Granuloma type** | Non-caseating | Non-caseating | | **Hypercalcemia** | Common (10–17%) | Rare | | **Elevated ACE** | Present (60–90%) | Absent or low | | **BeLPT** | Negative | Positive | | **Occupational history** | None | Beryllium exposure (aerospace, dental prosthetics, electronics) | | **Serum beryllium** | Normal | May be elevated | | **Urine beryllium** | Normal | May be elevated | **High-Yield:** BeLPT detects T-cell sensitization to beryllium. A positive test indicates the patient has been exposed to beryllium and has mounted a cell-mediated immune response, leading to granuloma formation. This is the most specific and reliable way to differentiate chronic berylliosis from sarcoidosis when both present with non-caseating granulomas. **Clinical Pearl:** The occupational history is crucial — beryllium exposure occurs in aerospace manufacturing, dental prosthetic labs, electronics, and metal recycling. Sarcoidosis is idiopathic and has no known occupational trigger. **Mnemonic:** **BeLPT = BEryllium Lymphocyte Proliferation Test** — positive in berylliosis, negative in sarcoidosis.