title: Post-radiation dedifferentiation of meningioma into osteosarcoma.
abstract: BACKGROUND
  A number of osteoblastic meningiomas, primary osteosarcomas of the meninges, and post-radiation osteosarcomas of the head have been reported. However, postradiation dedifferentiation of meningioma into osteosarcoma has not been reported previously.
  
  
  METHODS
  In 1987 a caucasian man, then 38 years old, presented with a pituitary macroadenoma. He underwent a subtotal resection of the tumor and did well until 1990 when a recurrent tumor was diagnosed. This was treated with subtotal resection of the tumor, followed by radiation therapy for six weeks to a total of 54 Gy. He was considered "disease-free" for nearly ten years. However, most recently in July 2000, he presented with a visual field deficit due to a second recurrence of his pituitary macroadenoma, now with suprasellar extension. At this time, as an incidental finding, a mass attached to the dura was noted in the left parietal hemisphere. This dura-based mass had grown rapidly by January 2001 and was excised. It showed histological, immunohistochemical, and electron microscopic features of malignant meningioma and osteosarcoma with a sharp demarcation between the two components.
  
  
  CONCLUSIONS
  We report a rare case of a radiation induced dedifferentiation of meningioma into osteosarcoma, which has not been reported previously.
authors.affiliation: Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA. vosipov@mail.mcw.edu
authors.forename: Vladimir
authors.initials: V
authors.lastname: Osipov
authors.forename: Khang-Che
authors.initials: KC
authors.lastname: Ho
authors.forename: Hendrikus G
authors.initials: HG
authors.lastname: Krouwer
authors.forename: Glenn
authors.initials: G
authors.lastname: Meyer
authors.forename: Vinod B
authors.initials: VB
authors.lastname: Shidham
mesh_terms: D000236:Adenoma / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D000328:Adult; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D004388:Dura Mater; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008577:Meningeal Neoplasms / Q000209:etiology / Q000473:pathology*; D008579:Meningioma / Q000209:etiology / Q000473:pathology*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D009381:Neoplasms, Radiation-Induced / Q000473:pathology*; D016609:Neoplasms, Second Primary / Q000209:etiology / Q000473:pathology*; D012516:Osteosarcoma / Q000209:etiology / Q000473:pathology*; D010911:Pituitary Neoplasms / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D011879:Radiotherapy Dosage