Right-Sided Chest Pain on Inspiration: Differential Diagnosis and Triage

Right-sided pleuritic chest pain (worsening with inspiration) localizes pathology to the right hemithorax, pleura, chest wall, or referred visceral structures.

Structured Differential by System

1. Pulmonary / Pleural
   • Pleurisy (viral, bacterial, autoimmune, PE-related) — sharp, localized, breath-dependent.
   • Pneumonia (lobar, right lower lobe common) — fever, productive cough, focal crackles.
   • Pulmonary embolism — sudden pleuritic pain, dyspnea, tachycardia, hypoxia; Wells/PE rule-out.
   • Pneumothorax (primary/spontaneous or secondary) — sudden pain, dyspnea, absent breath sounds.
   • Lung cancer (peripheral) — indolent pain, weight loss, smoking history.
2. Chest Wall / Musculoskeletal
   • Costochondritis (costosternal/chondrocostal joints) — reproducible tenderness, no systemic signs.
   • Rib fracture / stress fracture — trauma history, focal tenderness, crepitus.
   • Intercostal muscle strain — cough/exercise precipitated, tender on palpation.
   • Herpes zoster (pre-eruptive) — dermatomal burning, allodynia; vesicles follow.
3. Cardiovascular
   • Pericarditis — positional (better sitting forward), friction rub, diffuse ST elevation.
   • Acute coronary syndrome — atypical presentation (inferior MI → diaphragmatic irritation → right-sided pain).
4. Gastrointestinal / Hepatobiliary
   • Hiatal hernia / GERD — heartburn, regurgitation, postprandial.
   • Gallbladder disease (cholecystitis, biliary colic) — RUQ → referred to right chest/scapula.
   • Hepatic capsule stretch (hepatitis, congestion) — RUQ/right chest dull ache.

Red Flags for Immediate Emergency Evaluation

• Hemodynamic instability (hypotension, tachycardia >120, altered mental status)
• Severe dyspnea, SpO₂ <90%, cyanosis
• Syncope or near-syncope
• Crushing/pressure quality radiating to jaw/arm
• Known malignancy + new pleuritic pain

Diagnostic Pathway

History/exam → ECG, troponin, CXR, D-dimer (if PE probability low/mod) → CTPA or V/Q (if PE suspected) → CT chest (if neoplasm/infection) → US gallbladder (if RUQ features).

Pleuritic pain is never "just musculoskeletal" until life-threatening causes are excluded.