Viral Pleuritis

Inflammation of the pleura caused by viral infection, producing sharp pleuritic chest pain with or without a small effusion. It is common, self-limited, and a diagnosis of exclusion.

• Viruses: coxsackie B (epidemic pleurodynia, Bornholm disease, mainly in summer and autumn, with abrupt severe chest or upper abdominal wall pain lasting 2 to 14 days), other enteroviruses, echoviruses, influenza, adenovirus, parvovirus B19, Epstein-Barr virus, cytomegalovirus, SARS-CoV-2, and HIV seroconversion.
• Mechanism: direct viral injury and immune mediated inflammation of the pleural surfaces, with increased vascular permeability and a small, lymphocyte rich exudate in about 10 to 20%.
• The condition resolves in 1 to 2 weeks in most patients (relapses in pleurodynia occur in about 5 to 10%). In Kenya and other tuberculosis endemic areas, pleurisy with a lymphocytic exudate is tuberculous until proven otherwise, so do not label it viral too early.

• Sharp, stabbing pleuritic chest pain, worse on deep breathing, coughing or movement, often following a viral illness; fever, sore throat, myalgia, headache and dry cough. Pleurodynia gives paroxysmal severe pain in the chest or abdominal muscles lasting 15 to 30 minutes, with fever.
• Signs: pleural friction rub, splinting, shallow breathing, low grade fever; chest wall tenderness; reduced breath sounds with an effusion; normal oxygen saturation.
• Differential diagnosis: pulmonary embolism, pneumonia, pericarditis or myopericarditis, myocardial infarction, pneumothorax, tuberculous pleurisy, malignant pleural disease, rib fracture, costochondritis, herpes zoster before the rash, autoimmune pleuritis (lupus, rheumatoid arthritis), familial Mediterranean fever, drug induced pleuritis (nitrofurantoin, methotrexate, amiodarone) and subdiaphragmatic disease.
• Complications: small pleural effusion, pericarditis, myocarditis (coxsackie), prolonged pain, hypoventilation and atelectasis from splinting, and rare orchitis in coxsackie infection.

• Chest X-ray: normal or a small effusion (blunted costophrenic angle). Thoracic ultrasound shows a small effusion or thickened pleura.
• ECG and troponin to exclude pericarditis and myocardial infarction. D-dimer and CT pulmonary angiography when embolism is plausible (a validated clinical probability score can guide testing).
• Blood tests: full blood count, CRP (usually mildly raised), creatinine, HIV test, antinuclear antibody if suspicion of lupus, and viral PCR from throat swab or stool when it will change management (influenza, SARS-CoV-2, enterovirus).
• Diagnostic thoracentesis when an effusion is more than 10 mm thick and the diagnosis is unclear (or when fever persists): lymphocytic exudate with normal glucose and pH greater than 7.3 and adenosine deaminase less than 40 U/L is consistent with viral pleuritis; send Xpert MTB/RIF and culture for tuberculosis and cytology.
• Pleural biopsy (image guided or thoracoscopic) when an exudate persists beyond 2 to 4 weeks without a diagnosis.

• Reassure the patient about the benign course and the plan to return if symptoms worsen.
• Analgesia (the main treatment):
  • Ibuprofen 400 to 600 mg orally every 8 hours with food for 5 to 7 days (maximum 2400 mg/day), or naproxen 500 mg twice daily, or diclofenac 50 mg three times daily, with omeprazole 20 mg daily for patients at gastric risk. Avoid NSAIDs in renal impairment, peptic ulcer, heart failure, anticoagulation and late pregnancy.
  • Paracetamol 1 g orally every 6 hours (maximum 4 g/day), alone or with an NSAID.
  • Short course of opioid for severe pain: codeine 30 mg every 6 hours or morphine 2.5 to 5 mg every 4 hours; avoid larger doses because they suppress cough and breathing.
  • Heat packs on the chest wall, deep breathing exercises and incentive spirometry to prevent atelectasis; avoid tight chest strapping.
• Antiviral and antibacterial therapy:
  • Oseltamivir 75 mg twice daily for 5 days for confirmed or suspected influenza (start within 48 hours; later in severe disease).
  • No antibiotics unless there is evidence of bacterial infection.
  • Colchicine 0.5 mg twice daily for 3 months may be added when pericarditis coexists (evidence is limited for isolated pleuritis).
• Effusion: small effusions resolve without drainage; drain only for symptoms (breathlessness from a large effusion) or diagnosis.
• Fever and symptoms persisting beyond 7 to 10 days, enlarging effusion, or lymphocytic exudate: investigate for tuberculosis (pleural fluid adenosine deaminase, Xpert MTB/RIF, culture; pleural biopsy), malignancy, and autoimmune disease; start anti-tuberculosis therapy if the picture is tuberculous: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg (maximum 2 g) and ethambutol 15 mg/kg (maximum 1.2 g) daily for 2 months, then rifampicin and isoniazid for 4 months, with pyridoxine 25 to 50 mg daily.
• Special groups:
  • Children: ibuprofen 5 to 10 mg/kg every 6 to 8 hours, paracetamol 15 mg/kg every 6 hours; look for bacterial pneumonia with effusion.
  • Pregnancy: paracetamol; ibuprofen only before 20 weeks and avoid from 20 weeks onwards; exclude pulmonary embolism and pneumonia.
  • Elderly: use the lowest effective NSAID dose with omeprazole, or paracetamol alone; low threshold for imaging.
  • HIV: test for tuberculosis early, and exclude Pneumocystis and bacterial pneumonia.
  • Renal impairment: avoid NSAIDs when eGFR is less than 30.
• Red flags: fever beyond 72 hours, haemoptysis, breathlessness, hypoxaemia, enlarging effusion, weight loss or night sweats, ECG change or raised troponin, severe pain not controlled with simple analgesia.
• Follow up: review in 1 to 2 weeks; repeat chest X-ray at 4 to 6 weeks if an effusion was seen; return if pain relapses; counsel on hand hygiene and rest.