Tehran University of Medical Sciences Journal of Orthopedic and Spine Trauma 2538-2330 4 2 2020 05 05 35 37 Mahmoud Farzan Professor,Orthopedic Surgeon, Department of Orthopedic Surgery, ImamKhomeini Hospital Complex, Tehran University ofMedical Sciences, Tehran, Iran Amirreza Farhoud Assistant Professor, Orthopedic Surgeon, Department of Orthopedic Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Mohammad Zarei Assistant Professor, Orthopedic Surgeon, Department of Orthopedic Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Furqan Khan Resident, Orthopedic Surgeon, Department of Orthopedic Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran Mohammad Firoozabadi Resident, Orthopedic Surgeon, Department of Orthopedic Surgery, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran 2019 10 13 2020 01 14 Background: Osteoid osteoma (OO) is a benign osteoblastic neoplasm, mostly occurring in long bones of lower extremity. Its manifestation in unusual locations can be a diagnostic challenge and distressing for patients. OO in carpal bones is uncommon; its occurrence in triquetrum is even more so. Case Presentation: This study reports on a nineteen-year-old female with history of wrist pain for 4 years. She had sustained trauma to the same wrist before commencing of pain. Patient's pain was unresponsive to conservative treatments. Her routine x-rays were mostly interpreted as normal and obtaining further imaging helped us in diagnosis of OO of triquetrum. Surgical resection of the nidus was performed. Conclusions: Manifestation of OO in small carpal bones may not be typical; identifying the lesion or nidus could be challenging. Whatever unusual the location or presentation of such lesions may be, obtaining advanced imaging can be of significant help; therefore, we suggest clinicians to have low threshold in ordering advanced imaging specifically in patients suffering from chronic pain. Also, persistent history of nocturnal pain is a sign which is worth attention. https://jost.tums.ac.ir/index.php/jost/article/view/118 https://jost.tums.ac.ir/index.php/jost/article/download/118/121