title: Immunohistochemical diagnosis of a rare case of epithelioid malignant peripheral nerve sheath tumor with multiple metastases.
abstract: BACKGROUND
  The epithelioid variant of malignant peripheral nerve sheath tumor (MPNST) is a rare tumor with poor prognosis that sometimes involves the head and neck. The diagnosis is based principally on the histological examination, and it is generally very difficult to reach the correct diagnosis.
  
  
  METHODS
  An 84-year-old Japanese woman presented with a tumor mass of 2 week's duration in the right medial canthal region.
  
  
  METHODS
  Although the tumor was excised surgically, metastases occurred three times on her face and head, and the patient died of distant systemic multiple metastases. In the histopathological analysis, the tumor showed a composite pattern comprising spindle or polygonal cells arranged in irregular bands, and a population of larger epithelioid cells in solid sheets and nests. In the immunohistochemical analysis, the tumor cells were positive for S-100 protein, vimentin, and nerve growth factor receptor (NGFR), and negative for cytokeratin and HMB 45 (melanoma-associated antigen). These findings confirmed the diagnosis of MPNST.
  
  
  CONCLUSIONS
  Epithelioid MPNST has complex histopathological findings and histopathological features similar to other epithelioid tumors, especially malignant melanoma. Immunohistochemical examination using NGFR and HMB-45 is important in the differential diagnosis.
authors.affiliation: Department of Ophthalmology, Yamagata University School of Medicine, Yamagata 990-9585, Japan. dtsuchiya@ameria.org
authors.forename: Daijiro
authors.initials: D
authors.lastname: Tsuchiya
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takamura
authors.forename: Koko
authors.initials: K
authors.lastname: Saito
authors.forename: Hideo
authors.initials: H
authors.lastname: Kashiwa
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Maeda
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015622:Epithelioid Cells / Q000473:pathology*; D005142:Eyelid Neoplasms / Q000473:pathology* / Q000601:surgery; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009362:Neoplasm Metastasis; D018317:Nerve Sheath Neoplasms / Q000473:pathology* / Q000601:surgery; D010524:Peripheral Nervous System Neoplasms / Q000473:pathology* / Q000601:surgery