What are the next steps in managing a patient with a sclerotic focus in the scapula?

Management of Sclerotic Focus in Scapula

A sclerotic focus in the scapula is most likely a bone island (enostosis), a benign incidental finding that requires no treatment, but you must obtain plain radiographs first to confirm characteristic features, followed by bone scintigraphy if the diagnosis is uncertain or if the lesion lacks typical radiographic appearance. 1

Initial Diagnostic Approach

Plain Radiography (First-Line Imaging)

• Obtain standard radiographs of the scapula to characterize the sclerotic lesion's morphology 1
• Look for these pathognomonic features of bone island:
  • Homogeneously dense, sclerotic focus within cancellous bone 1
  • Distinctive radiating bony streaks ("thorny radiation") that blend with host bone trabeculae 1
  • Feathered or brush-like border at the margins 1
  • No associated soft tissue mass or cortical destruction 1

Advanced Imaging When Diagnosis is Uncertain

If plain radiographs show atypical features or the diagnosis remains unclear, proceed immediately to bone scintigraphy to differentiate benign from aggressive lesions. 1

• Bone scan characteristics:

  • Bone islands are typically "cold" (no uptake) on skeletal scintigraphy, which distinguishes them from malignant lesions 1
  • Critical caveat: Histologically confirmed bone islands can occasionally show scintigraphic activity, so do not rely solely on bone scan results 1
  • If the lesion is "hot" on bone scan but has classic radiographic features of bone island, correlation with CT or MRI is warranted 1

• CT findings (if obtained):

  • Bone island appears as a low-attenuation focus 1
  • Maintains characteristic radiating spicules into surrounding trabeculae 1

• MRI findings (if obtained):

  • Shows low signal intensity on all sequences, similar to cortical bone 1
  • No surrounding marrow edema or soft tissue component 1

Clinical Decision Algorithm

1. Asymptomatic sclerotic focus with typical radiographic features (thorny radiation, feathered border):

   • Diagnose as bone island 1
   • No further imaging or treatment required 1
   • Reassure patient this is a benign developmental variant 1

2. Sclerotic focus with atypical features (irregular borders, no thorny radiation, associated pain):

   • Obtain bone scintigraphy immediately 1
   • If "cold" on bone scan → likely bone island, consider short-term radiographic follow-up at 6 months 1
   • If "hot" on bone scan → obtain CT or MRI to evaluate for osteoblastic metastasis, osteoid osteoma, or other pathology 1

3. Patient with known malignancy and new sclerotic scapular focus:

   • Bone scan is mandatory to exclude metastatic disease 1
   • Consider biopsy if bone scan is positive and imaging features are atypical for bone island 1

Key Differentiating Features

The morphological features on plain radiography remain the most reliable diagnostic tool, with bone scan serving as confirmatory rather than definitive. 1

• Bone islands have a predilection for pelvis and long bones but can occur anywhere in the skeleton including the scapula 1
• The lesion is congenital or developmental, representing failure of resorption during endochondral ossification 1
• Size can vary but typically remains stable over time 1

Common Pitfalls to Avoid

• Do not order bone scan as first-line imaging — plain radiographs showing characteristic thorny radiation are diagnostic 1
• Do not assume all "cold" lesions on bone scan are benign — correlate with radiographic morphology 1
• Do not dismiss "hot" bone islands — documented cases exist where histologically proven bone islands show scintigraphic activity 1
• Do not confuse sclerotic contour loss with bone island — sclerotic contour loss on glenoid suggests bone loss from trauma or instability, not a bone island 2

When to Refer or Biopsy

• Refer to orthopedic oncology if:

  • Bone scan is positive AND radiographic features are atypical 1
  • Patient has known malignancy with new sclerotic lesion 1
  • Lesion demonstrates growth on serial radiographs 1
  • Associated pain or functional impairment is present 1

• Biopsy is rarely indicated but consider if:

  • High clinical suspicion for malignancy despite negative bone scan 1
  • Lesion lacks any characteristic features of bone island on all imaging modalities 1