What is the likely diagnosis and first‑line management for an adult with mild bilateral thoracic paraspinal swelling, tenderness, pain on forward flexion and rotation, but tolerated extension and no red‑flag features?

Thoracic Paraspinal Muscle Strain

This presentation is most consistent with thoracic paraspinal muscle strain, and first-line management should consist of conservative therapy without imaging: NSAIDs or acetaminophen for analgesia, activity modification with avoidance of provocative movements, physical therapy, and reassurance to remain active. 1

Clinical Reasoning

The clinical findings strongly suggest a musculoskeletal etiology rather than serious pathology:

• Bilateral paraspinal tenderness and swelling indicate muscle involvement rather than focal vertebral or disc pathology 1
• Pain with forward flexion and rotation is characteristic of muscle strain, as these movements stretch and load the paraspinal musculature 1
• Tolerated extension argues against compression fracture or significant disc herniation, which typically worsen with extension 2
• Absence of red flags (no neurologic deficits, no constitutional symptoms, no trauma history, no visible bruising suggesting fracture) makes serious pathology unlikely 2, 1

First-Line Management Protocol

Conservative therapy should be initiated immediately without imaging: 1

• Analgesics: NSAIDs (such as naproxen 375-500 mg twice daily) or acetaminophen for pain control 1, 3
• Activity modification: Avoid prolonged sitting, standing, and movements that reproduce pain (forward flexion, rotation) 1
• Physical therapy: Core strengthening and postural training once acute pain subsides 1
• Reassurance: Advise the patient to remain active within pain tolerance and that most mechanical back pain resolves with conservative management 1

Imaging Considerations

The American College of Radiology explicitly states that imaging is not warranted for thoracic back pain without red flags or neurologic deficits: 2

• No role for radiography, CT, MRI, or bone scan in the initial evaluation of this presentation 2
• Imaging should only be considered if there is little or no improvement after 4-6 weeks of conservative management 1
• Plain radiography of the thoracic spine would be the appropriate initial study if imaging becomes necessary after failed conservative therapy 1

Red Flags Requiring Immediate Imaging

Reassess at 4-6 weeks and maintain vigilance for emerging red flags that would necessitate MRI: 1, 4

• Myelopathy signs: Spasticity, hyperreflexia, positive Babinski sign, gait disturbance, or bladder dysfunction 2
• Progressive neurologic deficits: Motor weakness, sensory loss, or radiculopathy 2
• Constitutional symptoms: Fever, unexplained weight loss, night sweats suggesting infection or malignancy 4
• Severe or progressive pain despite adequate conservative management 2

Critical Pitfalls to Avoid

• Do not order premature imaging in the absence of red flags, as this increases costs without improving outcomes and may lead to incidental findings that complicate management 1
• Do not overlook myelopathy development, which requires immediate MRI evaluation even if it emerges during the conservative management period 1, 4
• Do not assume improvement means no follow-up is needed—reassess at 4-6 weeks to ensure resolution and rule out emerging red flags 1