## Clinical Context The imaging findings are pathognomonic for **osteoid osteoma**: - Well-defined, homogeneous lesion - Low T1 and T2 signal (sclerotic) - Dense central nidus on plain radiographs - No soft tissue mass or cortical destruction - No systemic features (fever, malaise) - Age 35 (typical range 10–40 years) ## Diagnosis and Management **Key Point:** Osteoid osteoma is a **benign, self-limited lesion** that is diagnosed on imaging alone. Biopsy is NOT required and may delay appropriate management. **High-Yield:** Classic imaging triad: 1. Central radiolucent nidus (< 1 cm) 2. Surrounding sclerotic bone 3. No cortical destruction or soft tissue mass **Clinical Pearl:** The hallmark clinical feature is **night pain exquisitely responsive to NSAIDs** — this is so characteristic that it is considered diagnostic. ## Management Algorithm ```mermaid flowchart TD A[Imaging findings suggest osteoid osteoma]:::outcome --> B{Diagnosis clear on imaging?}:::decision B -->|Yes| C[Start NSAIDs]:::action C --> D[Clinical follow-up + serial imaging]:::action D --> E{Symptoms resolve?}:::decision E -->|Yes| F[Continue conservative management]:::action E -->|No| G[Consider CT-guided ablation or surgery]:::action B -->|No| H[Biopsy]:::action ``` ## Why Conservative Management? | Feature | Implication | |---------|-------------| | Benign lesion | No malignant potential | | Self-limited | Typically regresses by age 40 | | NSAID-responsive | Symptom control is achievable | | No systemic features | No indication for urgent intervention | | Clear imaging diagnosis | Biopsy adds no diagnostic value | **Mnemonic:** **NIDUS** — **N**o biopsy needed, **I**maging diagnostic, **D**iagnosis benign, **U**se NSAIDs, **S**urgery only if refractory [cite:Robbins 10e Ch 26] 
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