Differentials: Right-Sided Neck Pain Radiating to Right Shoulder and Right Chest, Worse on Inspiration

MUST-NOT-MISS (Emergent / Life-Threatening)

1. Pulmonary Embolism (PE)

• Classic picture: Sudden-onset pleuritic chest pain, dyspnea, tachypnea, tachycardia. Pain is typically lateral/ipsilateral to the embolus. Pleuritic character arises from pulmonary infarction and overlying pleural inflammation.
• Key distinguisher: Dyspnea out of proportion to the chest pain, hypoxia, risk factors (DVT, immobility, OCP, malignancy, surgery).
• Workup: D-dimer + Wells score; CT pulmonary angiography if intermediate/high probability.
• Harrison's 22E, Table 15-1; Murray & Nadel's Respiratory Medicine, p. 888

2. Pneumothorax (Spontaneous or Traumatic)

• Classic picture: Sudden-onset pleuritic chest pain and dyspnea, lateral to the affected side. Right pneumothorax would produce right chest + ipsilateral shoulder/neck referral.
• Key distinguisher: Diminished breath sounds unilaterally, hyperresonance, tracheal deviation (tension).
• Workup: CXR (upright expiratory film); immediate needle decompression if tension.
• Harrison's 22E, Table 15-1

3. Acute Coronary Syndrome (ACS) / Myocardial Ischemia

• Right arm or bilateral arm radiation is actually the most strongly associated radiation pattern with ACS (likelihood ratio > 4). Right-sided neck/jaw/shoulder referral occurs.
• Pleuritic sharp pain somewhat reduces but does NOT exclude ACS (Tintinalli's).
• Key distinguisher: Risk factors (age >40, DM, HTN, smoking, family history); ECG; troponin.
• Tintinalli's Emergency Medicine, p. 2860; Harrison's 22E, Table 15-1

4. Aortic Dissection (Type A)

• Classic pain is ripping/tearing, radiating to the back (interscapular). However, branch occlusions can cause unusual radiation patterns including neck and shoulder pain.
• Unilateral pulse deficit, blood pressure differential, focal neurological deficits.
• Workup: CT aortogram / transesophageal echo.
• Tintinalli's Emergency Medicine, p. 2921

URGENT (Serious but Typically Not Immediately Life-Threatening)

5. Pleuritis / Pleurisy

• Mechanism (textbook-defined): The parietal pleura over the central hemidiaphragm is innervated by the phrenic nerve (C3-C5). Inflammation here causes viscerosomatic convergence at C3-C5 dorsal horn neurons, producing referred pain to the ipsilateral shoulder and neck. The chest wall pleura causes localized chest wall pain. Both can coexist, producing the exact triad described: right-sided neck + shoulder + chest pain, worse on deep breathing.
• "Taking a deep breath typically aggravates pleuritic pain. Coughing and sneezing cause intense distress."
• Causes of pleuritis include: viral (Coxsackie B, influenza), bacterial (para-pneumonic), connective tissue disease (lupus, RA), uremia, drug-induced.
• Murray & Nadel's Respiratory Medicine, pp. 888-889

6. Pneumonia (Right-Sided)

• Peripheral right-sided pneumonia extending to the visceral/parietal pleura causes pleuritic pain. Right lower lobe pneumonia can irritate the right hemidiaphragm, producing referred right shoulder/neck pain via the phrenic nerve.
• Associated features: fever, productive cough, hypoxia, crackles on auscultation.
• Tintinalli's Emergency Medicine, p. 2926

7. Pericarditis

• Pain is classically pleuritic and positional (worse supine, relieved by sitting forward). It typically radiates to the left shoulder, but radiation to the neck and both shoulders occurs.
• Key distinguisher: Pericardial friction rub, saddle-shaped ST elevation on ECG, relief by leaning forward.
• Harrison's 22E, Table 15-1; Tintinalli's, Table of life-threatening chest pain

SUBACUTE / NON-EMERGENT

8. Cervical Radiculopathy (C4-C5)

• Compression or irritation of the right C4 or C5 nerve root produces pain in the right neck, right shoulder, and can extend to the right upper chest (dermatome distribution). Deep breathing stretches the neck/thorax and can worsen the pain, mimicking pleurisy.
• Key distinguisher: Associated paresthesias, motor weakness in deltoid/biceps, aggravation by neck movement (Spurling's sign), no systemic features.
• Causes: cervical disc herniation, cervical spondylosis, foraminal stenosis.

9. Diaphragmatic Irritation from Subdiaphragmatic Pathology

• Any right subphrenic irritation (subphrenic abscess, liver abscess, right hemothorax, hepatic pathology, bile leak post-cholecystectomy) triggers phrenic nerve referred pain to the right shoulder tip and neck.
• "Irritation or inflammation of the diaphragm causes pain at the tip of the shoulder." Referral occurs because phrenic afferents converge with supraclavicular nerves at C3-C5.
• S Das Clinical Surgery; Gray's Anatomy for Students; Ganong's Review of Medical Physiology

10. Costochondritis / Musculoskeletal

• Right-sided costochondritis or intercostal muscle strain produces chest pain that is pleuritic in character (worse on inspiration) and can refer to the shoulder.
• Key distinguisher: Reproducible tenderness on palpation of the costochondral junctions; no systemic features; normal imaging.

11. Cholecystitis / Biliary Pathology

• Acute cholecystitis (right hypochondrial pain) classically refers to the right shoulder tip via the phrenic nerve (C3-C5 dermatome). Deep breathing distends the chest, stretching the inflamed peritoneum, worsening pain.
• Harrison's 22E, Table 15-1 (gallbladder disease listed among chest pain differentials)

12. Pulmonary Hypertension

• Can produce crushing/constricting substernal pain radiating to the neck or arms, and pleuritic chest pain with dyspnea. Consider especially if chronic symptoms.
• Murray & Nadel's, p. 888

Summary Table

Practical Initial Workup

1. ECG - immediately (ACS, pericarditis)
2. CXR - pneumothorax, pneumonia, PE signs, cardiomegaly
3. Troponin, D-dimer - based on clinical probability
4. O2 saturation - if hypoxic, PE/pneumothorax jump up in priority
5. CT pulmonary angiography - if PE suspected
6. CBC, CRP - infection/inflammation
7. Ultrasound RUQ - if cholecystitis/subphrenic pathology suspected
8. Cervical spine X-ray/MRI - if radiculopathy is leading differential after ruling out emergent causes

Clinical anchor: The right-sided specificity with phrenic nerve referral pattern (neck + shoulder tip + chest, pleuritic) most strongly points to right-sided pleuritis, right pneumonia, or right-sided PE as the top three, with ACS always in the background until excluded.