Purpose or Case Report: Osteoid osteomas of the hands and feet can be very challenging diagnoses to make. We attempt to assess diagnostic features to aid in detection and prevent delay of treatment.
Methods & Materials: A retrospective review of suspected osteoid osteoma was performed from May 2, 2006 to September 11, 2019, which yielded 1,157 patients from whom 8 patients had diagnosed osteoid osteoma involving the tubular bones of the hands and feet (6 girls and 2 boys, mean age of 12 years, range from 8 to 16 years). Picture archiving and communication system and electronic medical records were reviewed.
Results: A total of 8 patients were included in the analysis: 5 had histologically proven osteoid osteoma and 3 had indeterminate pathology results, but had a presumed diagnosis based on imaging findings, clinical history, and response to radiofrequency ablation/surgical excision of the lesion. A combination of radiography (n = 7), CT (n = 4), and MRI (n = 7) were used for diagnosis. Four (50%) osteoid osteomas occurred in the hand, involving the 5^th metacarpal, thumb metacarpal, 4^th proximal phalanx, and 4^th middle phalanx. Four (50%) occurred in the foot, involving the 3^rd metatarsal, 2^nd metatarsal, 1^st proximal phalanx, and second proximal phalanx. With the exception of 1 patient who had no recorded symptom duration, the delay between onset of symptoms and treatment averaged 21 months (range 8 to 61 months). A history of trauma to the area of the lesion at the onset of symptoms was noted for 3 patients (38%). Two patients (25%) with lower extremity lesions were athletes and had a history of either ipsilateral stress injury or contralateral fracture. On pre-intervention radiographs, available for 7 cases, six (86%) had widening of the shaft of the affected bone, 3 (43%) had cortical thickening, and 5 (71%) had a focal lucency within an area of sclerosis, suggesting a nidus. All 7 cases with MRI had a focal ovoid lesion surrounded by diffuse bone marrow edema in the affected bone with 2 of the 7 having the classic “target” lesion.
Conclusions: Noncontrast MRI can aid in the diagnosis of osteoid osteoma in the hands and feet with identification of a focal ovoid lesion and diffuse bone marrow edema in the affected bone, particularly if a targetoid lesion is identified. A full diagnostic work-up is essential to prevent delay in diagnosis and treatment, particularly in cases of confounding history.