title: Fine needle aspiration cytology of late-stage callus in stress fracture. A case report.
abstract: BACKGROUND
  Fine needle aspiration cytology (FNAC) is effective in the diagnosis of bone lesions when combined with careful radiologic and clinical evaluation. The cytologic features of callus have not been described before in the English-language literature.
  
  
  METHODS
  An 18-year-old female presented with a pain in the right lower leg that had been present for two months. Clinical and radiologic findings suggested either stress fracture or periosteal osteosarcoma. The aspiration specimen showed individually scattered, oval cells with moderate amounts of pale pink cytoplasm. The cells contained a single eccentrically located nucleus with evenly distributed, fine chromatin. Osteoclastic giant cells were scattered in the smears. A cytologic diagnosis of benign bone-forming lesion, compatible with callus in fracture, was made. The diagnosis of late-stage callus was confirmed by subsequent histologic examination.
  
  
  CONCLUSIONS
  Typical cases of stress fracture do not need histologic examination, but some cases may be confused with benign and malignant bone tumors. The typical and unique cytologic features of late-stage callus combined with clinical and radiologic findings may prevent the use of more invasive diagnostic procedures and can be a choice for management.
authors.affiliation: Departments of Anatomic Pathology, Orthopedic Surgery and Diagnostic Radiology, Korea Cancer Center Hospital, 215-4, Gongneungdong, Nowon-gu, Seoul 139-240, Korea.
authors.forename: J S
authors.initials: JS
authors.lastname: Koh
authors.forename: J H
authors.initials: JH
authors.lastname: Chung
authors.forename: M S
authors.initials: MS
authors.lastname: Kweon
authors.forename: S S
authors.initials: SS
authors.lastname: Lee
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D001707:Biopsy, Needle; D002146:Bony Callus / Q000473:pathology*; D005260:Female; D015775:Fractures, Stress / Q000000981:diagnostic imaging / Q000473:pathology* / Q000517:prevention & control; D006801:Humans; D011859:Radiography