title: A true intra-articular lipoma of the knee in a girl.
abstract: A 16-year-old girl presented with a soft-tissue mass in the anterolateral aspect of her right knee. Magnetic resonance imaging revealed an intra-articular tumor arising from the anterior fat pad of the knee. The tumor showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. It was resected under arthroscopic guidance. Grossly, the tumor was composed of soft, yellowish adipose tissue. Pathologic examination revealed a collection of mature adipocytes with marked myxoid changes in the matrix. A diagnosis of lipoma was made. True intra-articular lipomas should be distinguished from lipoma arborescens, which is considered to be a reactive process. In the English language literature, we found only 7 cases of true intra-articular lipoma reported previously. The present case is the youngest patient with such a tumor, and all the previous reports are of the tumor in adult patients. Intra-articular lipoma should be considered in the differential diagnosis of intra-articular masses in adolescents.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University School of Medicine, Kobe, Japan. tmarui@med.kobe-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Marui
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Kimura
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Akisue
authors.forename: Keiko
authors.initials: K
authors.lastname: Nagira
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakatani
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hitora
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000293:Adolescent; D001182:Arthroscopy; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008067:Lipoma / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D011859:Radiography; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000601:surgery