Osteoid Osteoma Mimicking Femoral Bone Metastasis in a Primary Laryngeal Cancer Case on PET/CT: Diagnostic Challenge

Abstract

Osteoid osteoma is a benign osteogenic tumor that may occasionally mimic malignant bone lesions on oncologic imaging. We report a diagnostically challenging case of a 59-year-old male with primary laryngeal squamous cell carcinoma in whom staging 18F-FDG PET/CT demonstrated intense uptake in the proximal femur, initially raising suspicion for skeletal metastasis. The patient had mild intermittent thigh pain with nocturnal exacerbation and rapid relief after nonsteroidal anti-inflammatory drug use. Further evaluation with magnetic resonance imaging demonstrated a small cortical-based lesion with surrounding sclerosis and bone marrow edema, while computed tomography revealed a central lucent nidus with reactive cortical sclerosis, findings consistent with osteoid osteoma. CT-guided biopsy confirmed the diagnosis histopathologically. The patient was managed conservatively with nonsteroidal anti-inflammatory drugs, and no systemic oncologic treatment was initiated for the femoral lesion. This case emphasizes that not all FDG-avid bone lesions in patients with known malignancy represent metastasis. Correlation of PET/CT findings with clinical features, MRI, CT, and histopathological confirmation when needed is essential to avoid misdiagnosis and unnecessary treatment.