Differential Diagnoses for Unilateral Periscapular Pain

Primary Musculoskeletal Differentials

Unilateral presentation of pleuritis or pleural irritation is typical for infectious or inflammatory pleural processes, according to Praxis Medical Insights 1

Axial Spondyloarthritis (axSpA) typically presents with bilateral sacroiliac involvement, but isolated spine involvement occurs in a minority of patients, with the thoracic spine and thoracolumbar junction being the most common sites of spinal involvement, as reported by the Journal of the American College of Radiology 2
Inflammatory back pain improves with exercise and worsens with rest, typically occurring at night, as noted by the Journal of the American College of Radiology 2
The unilateral periscapular location and worsening with hunching makes axSpA less likely than musculoskeletal causes, according to the Journal of the American College of Radiology 3 and 4

Cervical nerve root compression can refer pain to the periscapular region, typically accompanied by neck pain, arm symptoms, or neurologic deficits, as stated by Praxis Medical Insights 5

Fever, recent infection, IV drug use, or immunocompromised status suggest spinal infection, and history of cancer, unexplained weight loss, age >50 years, or failure to improve after 1 month suggest malignancy, according to Praxis Medical Insights 5
Rapidly progressive neurologic deficits or bladder/bowel dysfunction require immediate imaging, as recommended by Praxis Medical Insights 1

If pleuritic features dominate, consider chest imaging (radiograph or CT) to evaluate for pulmonary/pleural pathology, as suggested by the Journal of the American College of Radiology 4
If red flags are present, obtain urgent MRI and laboratory studies, including CBC, ESR, and CRP, as advised by Praxis Medical Insights 5