title: Postoperative spindle cell nodule after thyroidectomy: a case mimicking recurrence with anaplastic transformation of thyroid cancer.
abstract: BACKGROUND
  Here, we report a case of a postoperative spindle cell nodule that mimicked recurrence with anaplastic transformation after thyroidectomy.
  
  
  METHODS
  The course of the disease is described. The mass was studied morphologically and immunohistochemically.
  
  
  RESULTS
  A 31-year-old woman underwent total thyroidectomy for papillary thyroid carcinoma. A mass suspected of recurrence was found 14 months later and caused dysphagia and dyspnea. An (18)F-fluorodeoxyglucose positron emission tomographic ((18)F-FDG-PET) scan showed a lesion with high uptake; however, a fine-needle aspiration biopsy (FNAB) was inconsistent with recurrent cancer. The mass was resected and was composed of elongated spindle cells, with eosinophilic cytoplasm within a myxoid background. Immunohistochemical staining was strongly positive for vimentin, focally positive for smooth muscle actin, desmin, and p53, and negative for cytokeratin AE1/AE3, Cam5.2, epithelial membrane antigen (EMA), and anaplastic lymphoma kinase (ALK-1).
  
  
  CONCLUSIONS
  Although postoperative spindle cell nodules are rare after thyroid surgery, it should be considered in the differential diagnosis for recurrent masses at the operative site.
authors: Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors: Sun Wook
authors: SW
authors: Kim
authors: Young Lyun
authors: YL
authors: Oh
authors: Joon Young
authors: JY
authors: Choi
authors: Ji In
authors: JI
authors: Lee
authors: Jae Hoon
authors: JH
authors: Chung
authors: Jee Soo
authors: JS
authors: Kim
mesh_terms: D000328:Adult; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D049268:Positron-Emission Tomography; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000473:pathology*; D012008:Recurrence; D065646:Thyroid Carcinoma, Anaplastic; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy / Q000009:adverse effects*