Multinodular and Vacuolating Neuronal Tumor of the Cerebrum: A New "Leave Me Alone" Lesion with a Characteristic Imaging Pattern.

Multinodular and vacuolating neuronal tumor of the cerebrum is a recently reported benign, mixed glial neuronal lesion that is included in the 2016 updated World Health Organization classification of brain neoplasms as a unique cytoarchitectural pattern of gangliocytoma. We report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions located on the inner surface of an otherwise normal-appearing cortex, principally within the deep cortical ribbon and superficial subcortical white matter, which is hyperintense on FLAIR. Only 4 of our cases are biopsy-proven because most were asymptomatic and incidentally discovered. The remaining were followed for a minimum of 24 months (mean, 3 years) without interval change. We demonstrate that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

Review of xanthomatous lesions of the sella.

Xanthomatous lesions of the sellar region have traditionally been divided into two separate categories, xanthomatous hypophysitis (XH) and xanthogranuloma (XG) of the sellar region. The seminal article on XH, a condition typified by foamy histiocytes and lymphoplasmacytic infiltrates in the pituitary gland/sellar region, but usually little or no hemosiderin pigment, detailed three patients. However, most reports since that time have been single cases, making understanding of the entity difficult. In contrast, the seminal report on XG, characterized by sellar region cholesterol clefts, lymphoplasmacytic infiltrates, marked hemosiderin deposits, fibrosis, multinucleated giant cells around cholesterol clefts, eosinophilic granular necrotic debris, and accumulation of macrophages, included 37 patients, allowing more insights into etiology. Few examples could be linked to adamantinomatous craniopharyngioma, and although ciliated epithelium similar to that of Rathke cleft cyst (RCC) was identified up to 35% of the 37 cases, it could not be proven that XG was related to hemorrhage into RCC. Case reports since that time, however, occasionally linked XG to RCC when an etiology could be identified at all, and a few recognized that a spectrum exists in xanthomatous lesions of the sella. They review literature, adding 23 cases from our own experience, to confirm that overlap occurs between XH and XG, and that the majority-but not all-can be linked to RCC leakage/rupture/hemorrhage. It was suggested that progressive accumulation of hemosiderin pigment in the lesion, possibly caused by the multiple episodes of bleeding, could account for the transition of at least some cases of XH to XG.

Unsuspected varicella-zoster virus encephalitis in a child with acquired immunodeficiency syndrome.

We report a case of progressive encephalitis caused by varicella-zoster virus (VZV) in an adolescent with hemophilia and acquired immunodeficiency syndrome but without cutaneous signs of VZV infection. Magnetic resonance imaging of the brain demonstrated an abnormally increased periventricular signal in T2-weighted images. Infection with VZV was proved by in situ hybridization and immunofluorescence staining of brain tissue, which showed histologic evidence of herpesvirus infection. Encephalitis caused by infection with VZV is a potentially treatable complication of acquired immunodeficiency syndrome and requires a high index of suspicion for diagnosis.

Chronic progressive varicella-zoster virus encephalitis in an AIDS patient.

A patient with AIDS developed chronic, progressive encephalitis. Pathologic changes indicated that the encephalitis was produced primarily by a human herpesvirus. Hybridization of radiolabeled RNA probes transcribed from cloned DNA fragments of varicella-zoster virus (VZV), herpes simplex virus, cytomegalovirus, and the human immunodeficiency virus to DNA extracted from the patient's brain identified VZV as the causative agent. The results suggest that VZV should be considered in the differential diagnosis of chronic encephalitis of unknown etiology, particularly in immunosuppressed patients.