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Cholesterol granulomas (CGs) are benign lesions resulting from an inflammatory reaction to cholesterol and hemosiderin. These masses most often arise within the temporal bone or nasal sinuses; intracerebral CGs are extremely rare. In this report the authors present an unusual case of a CG arising within the lateral ventricle. The patient presented with transient hemiparesis and numbness. Computed tomography and magnetic resonance imaging demonstrated a cystic partially enhancing midline mass within the right lateral ventricle, expanding the ventricle and displacing the septum pellucidum. The patient underwent an interhemispheric, transcallosal resection of the lesion. Microscopic examination revealed a granulomatous inflammatory lesion containing cholesterol clefts, macrophages, and hemosiderin. Embedded within the granulomatous response were foci of tiny cystlike structures lined by nonciliated flattened cuboidal epithelium, consistent with the diagnosis of CG. To the authors' knowledge this is the first reported case of CG presenting as an intraventricular mass. The origin of this lesion is unclear, but it may relate to prior traumatic brain injury. The authors describe the presentation, imaging findings, histopathological characteristics, and surgical treatment of this rare lesion and related pathological entities.

Three patients with hypertension-induced basal ganglia or thalamic hemorrhage and ventricular rupture underwent corpus callosotomy and fenestration of the septum pellucidum. A patient with a left thalamic hemorrhage underwent surgery on an emergency basis and made a complete physical recovery, although she retained mild psychomotor deficits. Another patient with a large right basal ganglia hemorrhage who also underwent surgery on an emergency basis retained a spastic left hemiparesis without evident psychomotor deficits. The third patient with a left thalamic and basal ganglia hemorrhage, who was initially awake and then lapsed into stupor days later, underwent surgery, but did not recover consciousness. Hydrocephalus was reversed and effectively controlled in all three patients without having to perform a shunt placement procedure.

This case involved a 26-month-old boy who had recurrent hemorrhagic venous infarction caused by venous sinus occlusion. Distension and enlargement of the cavum septi pellucidi (CSP) and cavum vergae (CV), along with hydrocephalus, was detected during the course of the disease and was observed to regress together with resolution of the venous occlusion. Venous hypertension caused by sinus occlusion was thought to be responsible for the disturbed resorption of cerebrospinal fluid (CSF) in the CSP and CV in this patient. This case is unique because it is the first one to support the hypothesis of resorption of CSF in the cava by a pressure gradient involving the septal capillaries and veins.

Central neurocytoma was first described in the literature in 1982 and has been noted to be a benign neuronal tumor usually located in the ventricular system. Of the more than 100 reported cases, only seven recurrences have been reported, all of which have been local. The authors report two cases of recurrent central neurocytoma that disseminated through the ventricular system with seeding to the spine, as evidenced by magnetic resonance images and positive cerebrospinal fluid cytology. The histological appearance of these two tumors was typical for the lesion and lacked evidence of malignant change. Central neurocytoma may not be as benign as previously thought, and the recognition of this more malignant behavior has implications for patient follow up and therapy.

Expanding cysts of the septum pellucidum, although rare, may be a cause of significant neurological dysfunction. Most become symptomatic as a result of obstruction of the interventricular foramina and produce headaches, papilledema, emesis, and loss of consciousness. Behavioral, autonomic, and sensorimotor symptoms occur when an expanding cyst impinges on the structures of the hypothalamoseptal triangle or impairs the deep cerebral venous drainage. Neuroophthalmological symptoms may develop as a consequence of hydrocephalus or direct compression of visual structures. The authors describe the case of a young boy with an expanding septum pellucidum cyst who presented with a sudden, severe headache and loss of consciousness. In addition, he had a history of hyperactivity and progressively declining school performance. All symptoms resolved following decompression of the cyst. Seventeen cases from the literature are reviewed. The pathophysiological mechanisms underlying the development of symptoms secondary to expanding septum pellucidum cysts are outlined, and the related clinical neuroanatomy is described. A model is proposed for the natural history of expanding septum pellucidum cysts that provides a rational basis for understanding their clinical behavior and response to intervention. In most cases, fenestration or shunting will relieve the obstructive hydrocephalus and mass effect caused by the cyst and will produce rapid symptomatic improvement.