A 32-year-old Indian woman presents with acute onset of pain, photophobia, and blurred vision in the right eye for 3 days. On examination, visual acuity is 6/24, and slit-lamp reveals fine keratic precipitates, anterior chamber cells (3+ grade), and fibrin in the anterior chamber. Intraocular pressure is 18 mmHg. Fundoscopy shows mild vitritis with a few white infiltrates in the posterior pole. Chest X-ray is normal, and serum ACE level is normal. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Panuveitis with Undetermined Etiology ### Key Clinical Features **Key Point:** The presence of anterior chamber inflammation (keratic precipitates, cells, fibrin) combined with posterior segment involvement (vitritis and white infiltrates) defines panuveitis — inflammation affecting all three uveal layers. ### Differential Analysis | Feature | Present Case | Sarcoidosis | Bacterial Endophthalmitis | HSV Uveitis | | --- | --- | --- | --- | --- | | Keratic precipitates | Fine | Mutton-fat (granulomatous) | Absent/rare | Fine (non-granulomatous) | | Anterior chamber cells | 3+ | Moderate to heavy | Severe with hypopyon | Mild to moderate | | Fibrin | Present | Often | Heavy | Rare | | Vitritis | Mild | Mild | Severe/purulent | Moderate | | White infiltrates | Few | Snowball opacities | Diffuse | Focal | | IOP | Normal (18) | Often elevated | Often elevated | Variable | | Chest X-ray | Normal | Hilar lymphadenopathy | N/A | N/A | | ACE level | Normal | Elevated | N/A | N/A | **High-Yield:** The normal chest X-ray and normal serum ACE level effectively exclude sarcoidosis as the etiology, despite the granulomatous appearance of keratic precipitates. ### Why Panuveitis of Undetermined Etiology? 1. **Anterior + Posterior involvement** = panuveitis (not isolated anterior uveitis) 2. **Negative workup** = sarcoidosis ruled out (normal CXR, normal ACE) 3. **Non-suppurative** = excludes bacterial endophthalmitis (no hypopyon, mild vitritis, normal IOP) 4. **Non-herpetic features** = no dendritic keratitis, anterior uveitis alone (not panuveitis) typical of HSV ### Management Approach ```mermaid flowchart TD A[Panuveitis diagnosed]:::outcome --> B{Etiology identified?}:::decision B -->|Sarcoidosis| C[ACE elevated or CXR abnormal]:::action B -->|Tuberculosis| D[Mantoux, CBNAAT, systemic screening]:::action B -->|Toxoplasmosis| E[Focal retinitis + reactivation history]:::action B -->|CMV| F[Immunocompromised + hemorrhagic retinitis]:::action B -->|Idiopathic| G[Empiric corticosteroids + immunosuppression]:::action G --> H[Repeat investigations if no response]:::action ``` **Clinical Pearl:** Panuveitis with a negative systemic workup (normal CXR, normal ACE, negative TB screening) is common in India and often remains idiopathic; empiric corticosteroid therapy is initiated while awaiting response and further investigation. **Mnemonic: PANUVEITIS Causes — STITCH** - **S**arcoidosis - **T**uberculosis - **I**nfections (CMV, toxo, HSV) - **T**oxoplasmosis - **C**ancer-associated (masquerade) - **H**ypersensitivity (drug-related) [cite:Kanski's Clinical Ophthalmology 9e Ch 10]