title: So-called primitive neuroectodermal tumor in aborted previable fetuses.
abstract: We have described the gross anatomic and histopathologic characteristics of 36 tumorlike lesions found in previable fetuses. Although these lesions appear to be invasive, metastasizing, and likely contributing to the death of the fetus, they represent a frequent finding only among severely macerated retained fetuses of 9-16 developmental weeks and have never been found in fresh nonretained fetuses. No family history of neurofibromatosis could be elicited in any of these cases to support the suggestion in the literature that these tumors may represent fetal manifestations of neurofibromatosis. The most likely explanation is that they represent an artifact owing to squeezing of brain tissue into the spinal canal and along the spinal nerves into retroperitoneal and retropleural spaces or the neck area. As this artifact appears to be confined to a specific developmental period (9-16 weeks), it may be related to certain developmental characteristics such as a very soft consistency of brain tissue or incomplete development of vertebral foramina. A higher incidence of these lesions among heteroploid fetuses remains unexplained.
authors.affiliation: Department of Pathology, University of British Columbia, Vancouver, Canada.
authors.forename: D K
authors.initials: DK
authors.lastname: Kalousek
authors.forename: T
authors.initials: T
authors.lastname: Pantzar
authors.forename: R
authors.initials: R
authors.lastname: Craver
mesh_terms: D000782:Aneuploidy; D005260:Female; D005315:Fetal Diseases / Q000473:pathology*; D005865:Gestational Age; D006801:Humans; D009373:Neoplasms, Germ Cell and Embryonal / Q000473:pathology*; D011003:Ploidies; D011247:Pregnancy