title: Extramedullary hematopoiesis within a frontoethmoidal encephalocele in a newborn with holoprosencephaly.
abstract: We present the first report of extramedullary hematopoiesis (EMH) in an encephalocele. The patient was a new-born with semilobar holoprosencephaly, a frontoethmoidal encephalocele, and a large subdural hematoma. The encephalocele appeared as a hemorrhagic mass, protruding from the forehead to cover the right eye, without involvement of the sinuses or nasopharynx. Computerized tomography and magnetic resonance imaging studies ruled out other forms of holoprosencephaly and confirmed the continuity of the brain with the extruded mass. Immunohistochemistry confirmed the presence of an atrophic epithelium covering the mass. Histologic examination of the encephalocele revealed EMH both within and adjacent to malformed cerebral cortex, with a tendency for the hematopoietic cells to line up in columns within malformed cerebral cortex. We propose that a single event during the fourth week of gestation could both interrupt closure of the neural tube, giving rise to the encephalocele, and impair migration of the neural crest, leading to holoprosencephaly secondary to failure of neural crest derivatives to induce basomedial telencephalic differentiation. EMH may have been induced from hematopoietic stem cells in the richly vascular meningeal component of the encephalocele, in response to anemia and hypoxia.
authors.affiliation: Department of Neurology, Division of Pediatric Neurology, College of Physicians and Surgeons of Columbia University, 630 West 168th Street, New York, NY 10032, USA.
authors.forename: V E
authors.initials: VE
authors.lastname: Elgin
authors.forename: E S
authors.initials: ES
authors.lastname: Connolly
authors.forename: W S
authors.initials: WS
authors.lastname: Millar
authors.forename: N A
authors.initials: NA
authors.lastname: Feldstein
authors.forename: A J
authors.initials: AJ
authors.lastname: Dwork
mesh_terms: D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000002:abnormalities / Q000378:metabolism; D004677:Encephalocele / Q000150:complications / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005004:Ethmoid Bone / Q000002:abnormalities; D005624:Frontal Bone / Q000002:abnormalities; D006411:Hematopoiesis, Extramedullary; D016142:Holoprosencephaly / Q000150:complications / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007124:Immunoenzyme Techniques; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers