title: A case of acute subdural hematoma due to bleeding from metastatic chondrosarcoma of the skull.
abstract: BACKGROUND
  Intra or peritumoral hemorrhage of brain and skull tumors sometimes presents as stroke. Skull metastasis of chondrosarcoma is relatively rare, and furthermore, a case of intratumoural hemorrhage of skull metastasis of chondrosarcoma has not been reported.
  
  
  METHODS
  A 73-year-old man underwent right lower leg amputation in the past because of chondrosarcoma and was operated for a skull metastasis. He presented with a sudden headache, and head computed tomography revealed a right acute subdural hematoma (SDH) adjacent to the recurrent skull metastatic tumor. The removal of the SDH and tumor resection were performed emergently. The intraoperative findings included metastatic invasion beyond the dura mater to as deep as the subdural space, and the histological diagnosis was metastatic chondrosarcoma. His postoperative course was uneventful.
  
  
  CONCLUSIONS
  In the event of subdural invasion of a metastatic lesion, intratumoral hemorrhage may induce acute SDH, as in the present case. Similar to our case, most previous reports of intracranial chondrosarcoma hemorrhage have had an unclear etiology. Despite the rarity of this event, a patient with a history of malignancy presenting with nontraumatic acute SDH should be examined for the intratumoral hemorrhage of skull metastasis in the differential diagnosis.
authors.affiliation: Department of Neurosurgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Kosugi
authors.affiliation: Department of Neurosurgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takahashi
authors.affiliation: Department of Neurosurgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Sasaki
authors.affiliation: Department of Neurosurgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Tamura
authors.affiliation: Department of Pathology, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ohara
authors.affiliation: Department of Neurosurgery, Keio University School of Medicine, Shinjuku, Tokyo, Japan.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yoshida
keywords: Acute subdural hematoma; chondrosarcoma; intratumoral hemorrhage; skull metastasis