Abstract

Background: Osteoid osteoma is a benign bone tumor that typically affects young males. Its occurrence in older females is rare, often leading to diagnostic challenges due to atypical clinical and radiological features.
Case presentation: A 55-year-old female presented with a 6-month history of progressive nocturnal pain in the right thigh, which was partially relieved by nonsteroidal anti-inflammatory drugs. Initial X-ray imaging revealed subtle cortical lucency with mild surrounding sclerosis, initially suggestive of a stress fracture.
Investigations: Three-phase bone scintigraphy demonstrated focal increased uptake in the affected region. Subsequent SPECT/CT imaging confirmed increased Technetium-99m Methylene Diphosphonate uptake corresponding to a cortical nidus with central lucency and peripheral sclerosis, consistent with osteoid osteoma.
Diagnosis: Based on clinical presentation and imaging findings, a diagnosis of osteoid osteoma of the right femur was established.
Discussion: This case underscores the diagnostic difficulty of osteoid osteoma in older adults, where the presentation may mimic stress fractures or other cortical lesions. Advanced imaging modalities such as SPECT/CT play a crucial role in accurate lesion localization and differentiation from other pathologies.
Conclusion: Recognition of atypical presentations of osteoid osteoma in older adults is essential to avoid misdiagnosis and unnecessary interventions. Advanced imaging techniques are invaluable for confirming the diagnosis and guiding appropriate management.

Key words: Osteoid osteoma, elder female, bone scintigraphy, SPECT/CT, stress fracture, cortical nidus.