title: A spindle cell carcinoma presenting with osseous metaplasia in the gingiva: a case report with immunohistochemical analysis.
abstract: BACKGROUND
  Spindle cell carcinoma (SpCC) is a rare, high malignant variant of squamous cell carcinoma (SCC), which shows biphasic proliferation of conventional SCC component and malignant spindle shape cells with sarcomatous appearance.
  
  
  METHODS
  A case of Spindle cell carcinoma with bone-like calcified materials, occurring at the mandibular molar region of 71-years-old Japanese male patient was presented with gross finding, histological findings and MRI image. To identify the characteristics of the bone-like materials, immunohistochemistry were performed.
  
  
  RESULTS
  Histologically, the cancer cells were composed of spindle cells and epithelial cells which form nests with prominent keratinization. Histological findings showed typical histology of the SpCC, however, as an uncommon finding, spatters of calcified, bone-like materials were observed in between the cancer cells. Immunohistochemistry revealed that cancer cells were positive for cytokeratins and vimentin to a varying degree and negative for Desmin, S-100, Osteopontin, BMP-2 or BMP-4. These findings implied that the calcified materials were formed by metaplasia of the stromal cells.
  
  
  CONCLUSIONS
  Bone-like materials formation by osseous and/or cartilaginous metaplasia of the stroma in the carcinoma has been reported. However, the detailed mechanism of these metaplasia and affection on the clinical feature, prognosis and therapies are not well established. In summary, we presented an unique case of SpCC, which has not been described in the literature.
authors.affiliation: Department of Oral Pathology and Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan. gmd17099@cc.okayama-u.ac.jp
authors.forename: Naoki
authors.initials: N
authors.lastname: Katase
authors.forename: Ryo
authors.initials: R
authors.lastname: Tamamura
authors.forename: Mehmet
authors.initials: M
authors.lastname: Gunduz
authors.forename: Jun
authors.initials: J
authors.lastname: Murakami
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Asaumi
authors.forename: Goichi
authors.initials: G
authors.lastname: Tsukamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Sasaki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nagatsuka