title: Inflammatory pseudotumors of the central nervous system: report of 3 cases and a literature review.
abstract: Inflammatory pseudotumors (IPs), mostly benign lesions characterized by fibrotic ground tissue and polyclonal mononuclear infiltrate, may affect all organ systems. IPs originating in the central nervous system (IP-CNS) are very rare, and their distinct histopathologic features are poorly characterized. Three otherwise healthy patients (age 8, 15, and 17 years) presented with focal neurologic symptoms (seizures, n = 2; headaches, n = 1), corresponding to a left temporal, left occipital, and left frontal IP, respectively, extending from meningeal structures into brain tissue. After resection, no recurrence was observed in patient 1 during 5 years of follow-up, whereas patient 2 developed a rapidly progressive local recurrence and a second intracerebral lesion despite antiviral, immunosuppressive, antibiotic, and radiation therapy. In patient 3, who also showed local recurrences, sequential histopathologic investigations revealed transformation to a semimalignant fibrohistiocytic tumor. In this patient, anaplastic lymphoma kinase (ALK) expression was also positive, whereas it was negative in patient 1. A detailed literature analysis confirmed that most IP-CNS arise from dural/meningeal structures (n = 34). Intraparenchymatous (n = 7), mixed intraparenchymatous/meningeal (n = 4), and intraventricular lesions (n = 7) or IP extending per continuitatem from intracerebral to extracerebral sites (n = 5) were rare. The recurrence rate was 40% within 2 years in general. It was increased after incomplete resection and in female patients (multivariate Cox regression model, P < 0.02). Although rare, IP-CNS are important differential diagnoses among tumor-like intracranial lesions. Their potential risk of malignant transformation and high risk of recurrence necessitate close follow-up, especially when resection is incomplete. Prospective multicenter trials are needed to optimize classification and treatment of this rare inflammatory lesion.
authors.affiliation: Department of Pediatrics, University Hospital, RWTH Aachen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Häusler
authors.forename: Lars
authors.initials: L
authors.lastname: Schaade
authors.forename: Vincent T
authors.initials: VT
authors.lastname: Ramaekers
authors.forename: Martin
authors.initials: M
authors.lastname: Doenges
authors.forename: Gerhard
authors.initials: G
authors.lastname: Heimann
authors.forename: Bernd
authors.initials: B
authors.lastname: Sellhaus
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000134:cerebrospinal fluid; D001927:Brain Diseases / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D001932:Brain Neoplasms / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D002675:Child, Preschool; D004388:Dura Mater / Q000473:pathology; D005260:Female; D005625:Frontal Lobe; D006104:Granuloma, Plasma Cell / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D006801:Humans; D007074:Immunoglobulin G / Q000134:cerebrospinal fluid; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000473:pathology; D012008:Recurrence; D018139:Simplexvirus / Q000276:immunology; D013702:Temporal Lobe / Q000473:pathology
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G