title: Anaplastic transformation of follicular thyroid carcinoma in a metastatic skeletal lesion presenting with paraneoplastic leukocytosis.
abstract: BACKGROUND
  Anaplastic transformation of differentiated thyroid carcinoma (DTC) is a rare event with a poor clinical outcome. It usually occurs in the primary site or in regional lymph nodes, but rarely in distant metastatic lesions.
  
  
  CONCLUSIONS
  A 55-year-old woman with persistent pain in the left hip joint visited our hospital. She had a history of DTC that had been surgically removed 12 years earlier. Clinical images showed a tumorous mass in the left pelvis, indicative of bone metastasis. The patient underwent surgery to remove the tumor and remained stable until local recurrence was found 5 weeks after the surgery. The patient subsequently underwent radiation therapy; however, she died of respiratory failure due to lung metastases 2 months after the surgery for the recurrent lesion. The surgical specimens were diagnosed as anaplastic thyroid carcinoma, indicating that anaplastic transformation of thyroid follicular carcinoma occurred in the metastatic skeletal lesion. In addition, the patient had an unusually high white blood cell count throughout the course. Based on elevated serum granulocyte colony-stimulating factor (G-CSF) levels and positive immunostaining for G-CSF in the surgical specimens, the patient was diagnosed with paraneoplastic leukocytosis.
  
  
  CONCLUSIONS
  To our knowledge, this is the first case of anaplastic transformation of DTC arising in a metastatic bone lesion described in the literature. In addition, the present case also exhibited severe leukocytosis accompanied by elevated serum G-CSF levels. Clinicians should be aware of the possibility of this occurring in their patients with DTC, as this development calls for a rapid change from observational follow-up to aggressive treatment.
authors.affiliation: Department of Orthopedic Surgery, Keio University, Shinjuku-ku, Tokyo, Japan. robert@a2.keio.jp
authors.forename: Robert
authors.initials: R
authors.lastname: Nakayama
authors.forename: Keisuke
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Michiro
authors.initials: M
authors.lastname: Susa
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hosaka
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Kaori
authors.initials: K
authors.lastname: Kameyama
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yabe
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Hideo
authors.initials: H
authors.lastname: Morioka
mesh_terms: D018263:Adenocarcinoma, Follicular; D000708:Anaplasia; D001859:Bone Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D002277:Carcinoma / Q000097:blood / Q000556:secondary*; D017809:Fatal Outcome; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000097:blood; D006801:Humans; D007958:Leukocyte Count; D007964:Leukocytosis / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D008175:Lung Neoplasms / Q000097:blood / Q000000981:diagnostic imaging / Q000556:secondary; D008875:Middle Aged; D010146:Pain / Q000097:blood / Q000175:diagnosis; D010257:Paraneoplastic Syndromes / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D011859:Radiography; D013964:Thyroid Neoplasms / Q000097:blood / Q000473:pathology*
chemical_list: D016179:Granulocyte Colony-Stimulating Factor