Cerebellar PACNS in an Elderly Patient Present as a Tumor-Like Mass Lesion: A case Report.

Purpose: PACNS has a broad spectrum of clinical manifestations without typical features, and its clinical diagnosis is challenging. We report an elderly patient of cerebellar PACNS (Primary angiitis of central nervous system) presented as a brain tumor by MRI, and primary angiitis was proven by pathology.

Case report: We report an 81-year-old female who complained about vertigo for 3 weeks with right arm dysmetria. There were no other neurologic symptoms/signs, and the patient was free from headache. Brain CT showed a space-occupying lesion over the right cerebellum, and a high-grade glioma was suspected by brain MRI and MRS. The pathologic result of brain biopsy showed granulomatous variant of PACNS. The patient received immunosuppressant therapy as long-term therapy, and had favorable response during a 2-year follow up.

Conclusion: Due to variations in clinical presentation and nonspecific findings on imaging studies, PACNS is not easily diagnosed, especially in the aged population. PACNS should be considered as one of the differential diagnoses of any CNS dysfunction. PACNS is also an exclusionary diagnosis, so although brain biopsy is limited for its low sensitivity, its application is still important to exclude the possibility of other diseases. Although there have been reports of fulminant cases, PACNS can be treated successfully with immunosuppressant as maintaining therapy.