title: Adamantinoma of the distal femur diagnosed 5 years after initial surgery: a case report.
abstract: BACKGROUND
  Adamantinoma arising in the femur is extremely rare. We report a case of an adamantinoma occurring in the right medial femoral condyle that was diagnosed 5 years after the primary surgery.
  
  
  METHODS
  A 74-year-old Asian woman first complained of right knee pain without any cause. Radiographs demonstrated a 4×4.5 cm osteolytic lesion in her medial femoral condyle. Magnetic resonance imaging revealed a lesion which showed low signal on both T1 and T2-weighted image, and enhanced signal with gadolinium contrast administration. She underwent a wide resection of the lesion and was reconstructed with a tumor endoprosthesis. On histological examination, the tumor showed clusters of spindle-shaped and squamoid epithelial cells among the fibrous stroma. Adamantinoma was considered, however, the diagnosis was inconclusive due to the unusual localization and her age. Moreover, it was difficult to exclude metastatic carcinoma. Five years later, she was diagnosed with an abnormal shadow occupying the upper lobe of her right lung in a routine physical examination. She subsequently underwent a resection of the lung mass which histologically showed proliferation of spindle-shaped and squamoid epithelial cells. The histological similarity of the lung tumor and the femoral tumor led to the diagnosis of adamantinoma arising in her right medial femoral condyle with metastasis to the upper lobe of her right lung.
  
  
  CONCLUSIONS
  In this case report, we report the clinical, radiographic, and histological features of an adamantinoma arising in the distal femur with a review of the literature.
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.|Department of Orthopedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, 330006, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Cao
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. msusa@z6.keio.jp.
authors.forename: Michiro
authors.initials: M
authors.lastname: Susa
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Itsuo
authors.initials: I
authors.lastname: Watanabe
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Nishimoto
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Horiuchi
authors.affiliation: Division of Surgical Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Division of Surgical Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: Division of Surgical Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Katsura
authors.initials: K
authors.lastname: Emoto
authors.affiliation: Division of Surgical Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Kameyama
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Morioka
mesh_terms: D050398:Adamantinoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D000368:Aged; D057210:Delayed Diagnosis; D005260:Female; D005266:Femoral Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D011859:Radiography; D013125:Spinal Neoplasms / Q000473:pathology / Q000556:secondary*
keywords: Adamantinoma; Distal femur; Medial femoral condyle; Metastatic adamantinoma