What is the appropriate initial management for a 72-year-old man with two weeks of left posterior shoulder pain worsening with movement, described as pulling, recent resolved upper respiratory infection with cough, no fever, dyspnea, chest pain, or paresthesia, and mild swelling over the left trapezius?

Initial Management: Plain Radiographs of the Shoulder

This 72-year-old man requires plain shoulder radiographs as the initial diagnostic step, followed by urgent evaluation for potential serious pathology given the constellation of posterior shoulder pain, recent URI with cough, and trapezius swelling. 1

Immediate Diagnostic Approach

First-Line Imaging

• Order plain shoulder radiographs immediately (minimum 3 views: AP in internal/external rotation plus axillary or scapula-Y view) 1
• Radiographs are the preferred initial modality for acute shoulder pain and can identify fractures, dislocations, and massive rotator cuff tears

Critical Red Flags Requiring Urgent Evaluation

This patient's presentation raises several concerning features that must not be dismissed as simple musculoskeletal pain:

• Posterior shoulder pain with trapezius swelling in a 72-year-old warrants consideration of serious pathology
• Recent URI with cough temporally associated with shoulder symptoms suggests possible pulmonary involvement 2
• The "puffiness" over the trapezius is atypical for routine rotator cuff pathology

Differential Diagnosis Priority

Rule Out Serious Pathology FIRST:

1. Pulmonary causes (apical lung tumor/Pancoast tumor, pneumonia with referred pain) - the recent URI, cough, and posterior shoulder pain pattern is a classic presentation 2
2. Infection (osteomyelitis, septic arthritis, epidural abscess with referred pain)
3. Malignancy (primary bone tumor, metastatic disease)
4. Cervical spine pathology with referred pain 3

Physical Examination Essentials:

• Vital signs including temperature - fever would indicate infection 2
• Lung auscultation and percussion - assess for consolidation, effusion, or mass 2
• Cervical spine examination - assess for radiculopathy or myelopathy 3
• Palpate the trapezius swelling - assess for mass, lymphadenopathy, or fluctuance
• Shoulder range of motion - both active and passive to differentiate intrinsic shoulder pathology from referred pain

Management Algorithm

If Red Flags Present (fever, weight loss, night sweats, neurologic deficits):

• Immediate specialist referral (pulmonology if respiratory concerns, orthopedics/oncology if mass/malignancy suspected) 4
• Consider chest radiograph in addition to shoulder films given the URI history and posterior location 2
• May require urgent MRI if neurologic compromise or spinal pathology suspected

If No Red Flags and Radiographs Normal:

• Conservative management with education about favorable natural history 4
• Activity modification as needed
• Symptom relief (NSAIDs if not contraindicated in this 72-year-old)
• Watchful waiting with close follow-up 4

If Radiographs Show Pathology:

• Fracture: orthopedic referral for age-appropriate management 1
• Massive rotator cuff tear: expedited orthopedic referral (especially in traumatic tears requiring timely repair) 1
• Degenerative changes: conservative management initially 4

Critical Pitfalls to Avoid

Do not assume this is simple musculoskeletal pain. The combination of age (72), posterior location, recent respiratory symptoms, and visible swelling creates a clinical picture that demands exclusion of serious pathology 2. Shoulder pain can be the presenting symptom of pulmonary malignancy, particularly apical tumors that invade the brachial plexus and cause referred shoulder pain 2.

Do not order advanced imaging (MRI/ultrasound) before plain radiographs unless there is suspected serious pathology requiring immediate soft tissue evaluation 1, 4.

Do not delay referral if the clinical picture doesn't fit typical musculoskeletal patterns - persistent symptoms despite appropriate conservative management, unexplained swelling, or systemic symptoms warrant specialist evaluation 4.

The temporal relationship between the URI/cough and shoulder symptoms, combined with posterior location and trapezius swelling, makes this case higher risk than typical atraumatic shoulder pain and requires a more thorough initial workup than simple reassurance and conservative management.