AB157. SOH23ABS_193. Osteoid osteoma of the foot and ankle—the great masquerade

Background: First described by Bergstrand in 1930 osteoid osteoma (OO) is a benign, osteoblastic neoplasm. The tumour accounts for 5% of all bone neoplasms and approximately 11% of benign bone tumours worldwide. It most commonly affects the metaphyseal and diaphyseal regions of the tibia but can in theory affect any bone in the human body. The majority of information available in the literature consists of case reports or short case series, most commonly affecting children and young adults.

Methods: This was a retrospective cohort based study involving a case series.

Results: We present a case series of three adults diagnosed with OO. All three patients endured an arduous journey to their definitive diagnosis and eventual treatment. A mean time to diagnosis of fifteen months underpins the difficult clinical conundrum posed in such cases. Improvements between standardised pre- and post-operative functional scores illustrate the effectiveness of surgical intervention in OO. A phenomenon, which is well described in the literature. Severe night pain, another hallmark feature of OO was experienced by two patients while only one patient reported significant improvement in their symptoms from taking non-steroidal anti-inflammatory drugs (NSAIDs) despite current evidence suggesting the contrary.

Conclusions: Currently there is a paucity of information pertaining to OO in older adults. Less than 5% of published literature describing the condition in patients over 40 years old. The age range of our cohort is 34–61. The current case series therefore expands current weaknesses in the literature and reinforces the importance of a broad list of differential diagnoses when treating foot and ankle conditions irrespective of age.

Keywords: Ankle; bone neoplasm; benign tumour; foot; osteoid osteoma (OO)