title: Intra-articular synovial lipoma of the knee joint (located in the lateral recess): a case report and review of the literature.
abstract: This report describes a rare intra-articular synovial lipoma of the knee joint which developed in a 66-year-old female. The patient suffered from sudden knee pain and a catching or slight interruption of normal motion of the left knee and then noticed the tumor. The tumor was located in the lateral recess of the knee joint and showed a signal intensity similar to subcutaneous fat on T1 and T2()-weighted magnetic resonance images. The arthroscopy revealed a smooth, globular, yellowish, encapsulated tumor extending into the lateral recess from the surface of the lateral condyle and the tumor was totally excised under arthroscopic guidance. Histologic examination of the specimen revealed a tumor composed of mature adipose cells covered by a thin fibrous layer of varying thickness and normal synovial lining cells. The diagnosis was intra-articular synovial lipoma. Intra-articular synovial lipomas should be distinguished from other similar lipomatoid conditions such as Hoffa disease and villous lipomatous proliferation of the synovial membrane (lipoma arborescens). Intra-articular synovial lipoma should be considered in the differential diagnoses when examining a patient with sudden knee pain, and a catching or locking knee.
authors.affiliation: Department of Orthopaedic Surgery, Nagano Red Cross Hospital, 5-22-1 Wakasato, Nagano, Nagano Prefecture 380-8582, Japan. kenichi923hirano@ybb.ne.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hirano
authors.forename: Masao
authors.initials: M
authors.lastname: Deguchi
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kanamono
mesh_terms: D000328:Adult; D001182:Arthroscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis* / Q000601:surgery; D007719:Knee Joint / Q000601:surgery; D008067:Lipoma / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000601:surgery