Abstract：Objective: To describe the MRI features of the tumor-mimicking primary angiitis of the central nervous system(PACNS) and to discuss MR diagnostic value of the tumor-mimicking PACNS. Materials and Methods: Eight patients with biopsy-proven PACNS mimicking brain tumor underwent MRI were reviewed. The findings of MR imaging were retrospectively analyzed and the clinical symptoms were also analyzed. Results: MR imaging demonstrated solitary mass in 6 cases, and multiple mass in 2 cases. On T1WI, the lesions showed homogeneous low signal in 3 cases, and mixed high and low signal in 5 cases. On T2WI, the lesions presented as homogeneous high signal in 3 cases and inhomogeneous high signal in 5 cases. All 8 cases with Gd-DTPA administration, marked enhancement was seen. All lesions of 8 cases showed mass-like enhancement. Conclusion: It is a difficult task to make the correct diagnosis of the tumor-mimicking PACNS, and this disease entity is often misdiagnosed as tumor by MRI. The comprehensive understanding of the MRI characteristic features would be helpful in diagnosing the tumor-mimicking PACNS, thus avoiding the devastating injury caused by surgery. The definite diagnosis relies on brain biopsy.
2010, Vol. 21 
