What is the likely cause of firm swelling and tenderness at the anterior shoulder distal to the acromioclavicular joint in a 50-year-old male, 4 months after a fall from 3 feet, with pain on overhead reach, minimal pain with forearm flexion, normal X-ray, and CT arthroscopy concerns over the labrum, without access to MRI?

Likely Diagnosis: Anterior Labral Tear with Possible Associated Rotator Cuff Pathology

The most likely cause of firm swelling and tenderness at the anterior shoulder distal to the AC joint, 4 months post-trauma with CT arthrography concerns over the labrum, is an anterior labral tear (likely Bankart lesion) with possible associated rotator cuff injury, given the patient's age and mechanism of injury. 1, 2

Clinical Reasoning Based on Presentation

Age and Mechanism Support Dual Pathology

• At 50 years old, this patient falls into a critical transition zone where both labral tears and rotator cuff pathology commonly coexist after traumatic shoulder injuries 1
• The American College of Radiology specifically notes that older patients (>40 years) are more likely to have rotator cuff tears in association with shoulder dislocation or instability, while younger patients predominantly have isolated labroligamentous injury 1, 2
• A fall from 3 feet with tumbling mechanism provides sufficient energy for both anterior labral disruption and rotator cuff injury 1, 3

Symptom Pattern Analysis

• Pain with overhead reach strongly suggests rotator cuff involvement, as this is the classic presentation of rotator cuff tendinopathy or tear 3, 4
• Minimal pain with forearm flexion helps exclude biceps tendon pathology as the primary diagnosis 1
• The firm swelling at the anterior shoulder distal to the AC joint is consistent with chronic labral pathology, capsular thickening, or organized hematoma from the initial injury 5
• Four-month duration indicates chronic, unhealed pathology requiring definitive imaging and likely surgical evaluation 2

CT Arthrography Findings

• The CT arthrography showing "concern over labrum" is significant because CT arthrography is comparable to MR arthrography for diagnosing Bankart and Hill-Sachs lesions 1
• However, CT arthrography is inferior to MR arthrography for assessing partial-thickness rotator cuff tears, which may be missed in this patient 1
• The American College of Radiology notes that CT arthrography has only moderate inter-observer agreement for anterior capsular laxity, so the labral concern should be taken seriously 1

Specific Differential Considerations

Primary Diagnosis: Anterior Labral Tear (Bankart Lesion)

• Bankart lesions are anterior labral tears with or without bony fragments that occur from anterior shoulder instability or dislocation 3
• The anterior location of tenderness and swelling directly correlates with Bankart lesion anatomy 5
• SLAP lesions (superior labrum) would cause pain more superiorly and typically present differently 5

Associated Pathology: Rotator Cuff Tear

• Pain with overhead activities is a cardinal sign of rotator cuff pathology 3, 4
• The American College of Radiology emphasizes that up to 10% of patients with recurrent shoulder instability have coexisting rotator cuff tears, and this percentage increases significantly in patients over 40 years 1
• CT arthrography may have missed a partial-thickness rotator cuff tear given its known limitations 1

Less Likely: AC Joint Osteoarthritis

• While AC joint arthritis presents with superior shoulder pain and tenderness over the AC joint 3, 6, 7, the description specifies the tenderness is distal to (below) the AC joint, making this less likely 6, 8
• AC joint pathology typically causes pain with cross-body adduction, which was not mentioned 4, 7

Critical Next Steps

Imaging Recommendation

• Despite inability to obtain MRI, you must advocate strongly for MR arthrography as it is the gold standard with 86-100% sensitivity for labral tears and superior assessment of rotator cuff pathology 1, 2
• If MRI is truly contraindicated (pacemaker, severe claustrophobia, metallic foreign body), the existing CT arthrography is acceptable but incomplete 1, 2
• Request specific review of the CT arthrography for:
  • Anterior labral detachment (Bankart lesion) 1
  • Hill-Sachs lesion (posterolateral humeral head compression fracture) 1, 3
  • Glenoid bone loss 1
  • Full-thickness rotator cuff tears (CT arthrography can detect these) 1

Physical Examination Maneuvers to Perform Now

• Empty can test (supraspinatus): Pain or weakness suggests rotator cuff tear 3, 4
• External rotation resistance test: Weakness indicates infraspinatus/teres minor pathology 3, 2
• Apprehension and relocation tests: Positive findings confirm anterior instability from labral injury 4
• Cross-body adduction test: If painful, reconsider AC joint involvement 4, 7

Orthopedic Referral Indications

• This patient requires orthopedic consultation given the 4-month duration, persistent symptoms, and imaging evidence of labral pathology 2
• The American College of Radiology notes that glenoid bone loss can play a significant factor in recurrent shoulder dislocations and may require bone grafting 1
• Surgical stabilization may be necessary if conservative management has failed over 4 months 2

Common Diagnostic Pitfalls to Avoid

Do Not Assume Single Pathology

• The most critical error would be attributing all symptoms to the labral tear alone without evaluating for concomitant rotator cuff injury 1, 2
• The American College of Radiology specifically warns that older patients with dislocation commonly have rotator cuff tears that require different surgical approaches 1

Do Not Dismiss the Firm Swelling

• Persistent firm swelling at 4 months post-injury is abnormal and may represent chronic capsular thickening, organized hematoma, or even low-grade infection 5
• If there are any systemic symptoms (fever, chills, elevated inflammatory markers), septic arthritis must be excluded with arthrocentesis 1, 9

Do Not Delay Definitive Management

• Four months of symptoms without resolution indicates failed conservative management and warrants surgical evaluation 2, 8
• The American College of Radiology notes that up to 10% of patients with recurrent instability develop progressive glenoid bone loss, which worsens surgical outcomes if delayed 1