title: Malignant pigmented villonodular synovitis in the knee - report of a case with rapid clinical progression.
abstract: Malignant pigmented villonodular synovitis (PVNS) (or malignant giant cell tumor of tendon sheath (GCTTS) is an extremely rare condition defined as a malignant lesion occurring with concomitant or previously documented PVNS at the same site. To date, only less than 20 cases have been reported in English literatures. We report a case of malignant PVNS in the knee in a 56-year-old woman with unpredictable rapid progression. This case raised a caution that when atypical components in specimens of recurrent benign PVNS are detected, even if low-grade or tiny, both pathologists and surgeons should consider the risk of malignant PVNS, which could display aggressive clinical progression.
authors.affiliation: Department of Orthopaedic Surgery, Kyorin University Faculty of Medicine. 6-20-2 Shinkawa Mitaka Tokyo 181-8611 Japan.
authors.forename: Naoaki
authors.initials: N
authors.lastname: Imakiire
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujino
authors.forename: Takeshi
authors.initials: T
authors.lastname: Morii
authors.forename: Keita
authors.initials: K
authors.lastname: Honya
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Satomi
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Fujioka