Sinus histiocytosis with massive lymphadenopathy, or Rosai–Dorfman disease (RDD), was first described in 1969 as a reactive condition of unknown etiology that is characterized by a proliferation of histiocytes exhibiting emperipolesis of both lymphocytes and plasma cells. It usually presents with painless cervical lymphadenopathy either with or without extranodal manifestations. Intracranial involvement of this disease is extremely rare. Intracranial RDD occurs in <5% of all patients with extranodal disease. Here, we report a case of RDD with isolated intracranial involvement. A 67-year-old male presented with a long-standing headache, retro-ocular pain, and progressive visual loss of the left eye. Magnetic resonance imaging showed features of optic nerve meningioma. The histopathology revealed sheets of histiocytes displaying emperipolesis. These histiocytes were S100 positive; however, a CD1a and epithelial membrane antigen were negative.
Arachnoid cysts (ACs) within the fourth ventricle are rare, and only a few cases have been reported in the literature. These are benign lesions within the arachnoid membrane, and they have been reported to occur in almost all locations where arachnoid is present. Different procedures have been performed to restore a normal cerebrospinal fluid dynamic and/or pressure, including shunting and partial or complete excision of the cyst by open microsurgery or endoscopic fenestration. We report the case of a fourth ventricle AC successfully treated using only endoscopic anterior trans-frontal cyst fenestration/marsupialization and standard third ventriculostomy. Clinical and technical features are discussed, along with the pertinent literature.
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