Can Pneumonia Cause Referred Right Shoulder Pain?
Yes, pneumonia can definitively cause referred shoulder pain through diaphragmatic irritation transmitted via the phrenic nerve (C3-C5), which shares the same dermatome as the shoulder region. 1, 2
Mechanism of Referred Pain
The pathophysiology involves irritation of the diaphragm from adjacent pneumonia (particularly right lower lobe), with sensory signals transmitted through C4 sensory axons in the phrenic nerve that share dermatomal distribution with the acromion and shoulder area. 2 This creates a classic pattern of referred pain that can be the presenting symptom of pneumonia, especially in patients with right lower lobe involvement. 1
Clinical Recognition in Your Patient
Given your patient's presentation—severe cough and dyspnea two weeks ago followed by right shoulder and right anterior chest wall pain—pneumonia remains a strong diagnostic consideration despite recent corticosteroid treatment. 1
Key diagnostic features to assess:
- Pleuritic chest pain is specifically listed as suggestive of pneumonia and may manifest as chest wall or referred shoulder pain 1
- Fever ≥38°C, tachypnea, or new focal chest signs (crackles, diminished breath sounds, dull percussion) significantly increase pneumonia likelihood 1, 3
- Absence of rhinorrhea combined with breathlessness and focal findings substantially increases probability 1, 3
Diagnostic Algorithm
Step 1: Physical Examination
Perform focused examination looking for:
- Dull percussion note or pleural rub (highly specific for pneumonia) 3
- New focal crackles or diminished breath sounds in discrete lung regions 3, 4
- Tachypnea >24 breaths/minute 5
- Oxygen saturation <92% 1
Step 2: C-Reactive Protein Testing
If focal signs present without fever: 1, 5
- CRP >30 mg/L with symptoms/signs strongly suggests pneumonia—proceed to chest radiography
- CRP <10 mg/L makes pneumonia less likely
- CRP 10-50 mg/L is intermediate—clinical judgment required
Step 3: Chest Radiography
Obtain chest X-ray when: 1, 3, 5
- Abnormal vital signs plus focal chest findings
- CRP >30 mg/L with suggestive symptoms
- Symptoms persist or worsen despite initial treatment
Critical Caveat About Corticosteroid Use
Your patient received triamcinolone and methylprednisolone, which creates a diagnostic challenge. While corticosteroids may provide symptomatic relief and reduce inflammatory markers, they can mask typical pneumonia presentations and potentially delay diagnosis. 6, 7 The corticosteroids may have temporarily suppressed fever and reduced inflammatory response without treating underlying bacterial infection.
The shoulder pain developing after corticosteroid treatment suggests either:
- Incomplete treatment of pneumonia with symptom unmasking as steroids wear off
- New or progressive pneumonic process
- Diaphragmatic irritation from persistent lower lobe involvement 2, 8
Immediate Management Recommendations
Obtain chest radiography now given the combination of recent respiratory illness, corticosteroid exposure, and new shoulder/chest pain 1, 3
If chest X-ray confirms pneumonia, initiate empiric antibiotics according to local guidelines (broader coverage than simple amoxicillin given corticosteroid exposure and symptom persistence) 5
Reassess in 48-72 hours to ensure clinical improvement 3
Monitor for complications including treatment failure, as corticosteroid use without concurrent antibiotics in bacterial pneumonia can worsen outcomes 6
Common Pitfall to Avoid
Do not dismiss shoulder pain as purely musculoskeletal without ruling out pneumonia, particularly in patients with recent respiratory symptoms and right-sided pain. 2 The case literature specifically warns that pneumonia presenting as shoulder pain is under-recognized and can lead to delayed diagnosis and treatment. 2, 8