Choroid Plexus Xanthogranuloma: Is it an Incidental Finding?

A woman aged 48 years presented with sudden onset tinnitus that improved after 2 weeks. She had no headache or hearing loss. Her general and neurologic examinations were normal. The patient was using venlafaxine 75 mg/day. Brain magnetic resonance imaging (MRI) performed to exclude intracranial pathologies, showed bilateral choroid plexus xanthogranulomas at the level of atrium of the lateral ventricles, which were hypointense on T1weighted imaging, hyperintense on T2-weighted imaging and diffusion-weighted imaging (DWI) (Figure 1). The patient, whose symptoms improved, was informed about her xanthogranulomas and followed up without medical treatment. Xanthogranulomas are benign tumors that consist of cholesterol clefts, lymphocyctic infiltration, giant cells with multiple nucleoli, foamy macrophages (xanthoma cells), fibrous proliferation, and hemosiderin deposits. As one of the rarest lesions of the central nervous system, the incidence of xanthogranulomas on autopsy is reported as 1.6-7% (1). The frequency of intraventricular tumors of the central nervous system is 10% and only 1% of this group contains lateral ventricle tumors, including astrocytomas and choroid plexus papillomas as the most common, and others including meningiomas, ependymomas, central neurocytomas, xanthogranulomas, and metastases (2). The mechanism is not well known but continuous proliferation of the choroid plexus epithelium, entrance of desquamated epithelial cells into the interstitium of the plexus by breaking the basal lamina and the walls of the tube, releasing lipids into the choroid matrix following destruction of lipid-loaded foam cells, lipid deposition in the epithelium, and stimulation of macrophages and multinucleated foreign-body giant cells by degenerated cells, which causes an increase in lipid deposition in the stroma of the plexus, are thought to be possible mechanisms. Also, arteriolar neogenesis and hemorrhages cause development of hemosiderin granules and deposition of these granules contribute to the pathology (3). Xanthogranulomas have heterogeneous radiologic features because of their lipid and blood components. The diagnostic values of computed tomography (CT) and MRI are limited. CT can show ovoid, round-shaped (like colloidal cysts) or smooth-walled lesions and calcifications. They can be hypo, iso or hyperdense because of their heterogeneous components on CT. MRI cannot distinguish xanthogranulomas from other lesions of lateral ventricles including meningiomas, papillomas, ependymomas and arteriovenous malformations, because they can be cystic or solid. Due to outer cell lipid deposition, they can be hyperintense on T1-weighted imaging. Also, they can be hyperintense or isointense on T2weighted imaging. Diffuse or rim-like contrast enhancement can be seen on MRI. The hyperintense appearance on DWI is the most