Childhood primary angiitis of the central nervous system (cPACNS) is a rare and poorly understood immune-mediated vasculitis that preferentially affects blood vessels of the central nervous system (CNS). It must be distinguished from other disorders to initiate prompt treatment and improve the patient's prognosis. The presentation of cPACNS is highly variable, making a clinical diagnosis challenging. However, MRI may be helpful in showing typical findings including perivascular space inflammation and enhancement. Identification of these imaging features allows the radiologist to specifically suggest this rare diagnosis. The purpose of this manuscript is to present a biopsy-confirmed case of cPACNS in a 9-year-old girl who presented uniquely with panuveitis and anisocoria, and emphasize the MRI features that should prompt the radiologist to suggest this rare diagnosis.