Abstract:Objective To explore the imaging features of intraosseous schwannoma (IOS) involving the spine in order to differentiate it from other spinal osteolytic lesions. Methods We retrospectively analyzed the clinical data, CT and MRI of IOS involving the spine confirmed by surgery and pathology in Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine. We collected 11 cases of IOS involving the spine, including 7 males and 4 females, aged 23-74 years [average age (51 ± 17) years]. All patients underwent CT and MRI examinations. Two senior bone and joint system radiologists evaluated the imaging features and reviewed literatures reported in recent years. Results The IOS involved 3 cases of cervical spine (3/11, 27.3%), 1 case of thoracic spine (1/11, 9.1%), 5 cases of lumbar spine (5/11, 45.5%), and 2 cases of lumbosacral spine (2/11, 18.2%), with a maximum diameter of (5.8 ± 2.85) cm and an irregular shape. CT showed eccentric expansive osteolytic bone destruction with uneven density. The average CT values on plain scan were (43.0 ± 11.55) HU. After enhancement, the lesions showed uneven mild enhancement, with an average CT value of (70.3 ± 12.22) HU. The boundaries of the lesions were clear, with sclerotic edges and no periosteal reaction. The lesions were prone to extend along the intervertebral foramen to the inside and outside of the vertebral canal. On MRI, compared with muscle tissue, the lesions showed equal low signal intensity on T1WI,mixed slightly high signal intensity on T2WI, mixed high signal intensity after fat suppression, and no diffusion limitation on DWI with the average ADC value of 1.25 ± 0.176 × 10-3mm2/s. After enhancement, the lesions showed uneven and significant enhancement, with a time signal intensity curve (TIC) of type I and cystic changes occurring in 7 lesions. Conclusion IOS involving the spine is a rare benign tumor with certain characteristic imaging features, which should be considered in the differential diagnosis of heterogeneous spinal osteolytic lesions with clear boundaries.