title: Hepatic metastases from the spindle cell variant of medullary thyroid carcinoma: report of a case with diagnosis by fine needle aspiration biopsy.
abstract: BACKGROUND
  The liver is a common site of neuroendocrine tumors (NTs) metastatic from primaries in the gastrointestinal tract, pancreas, biliary system and lungs. Medullary thyroid carcinoma (MTC) is also a potential source of metastases of NTs. Their metastases to the liver are frequent and can appear several years after the primitive tumor. Although a wide variety of cytomorphologic features are normally exhibited by MTC in smears, a spindle-shaped cell pattern can predominate, complicating the correct interpretation of a metastasis.
  
  
  METHODS
  A 63-year-old man presented with multiple liver nodules two years after a total thyroidectomy for MTC. Fine needle aspiration biopsy smears of the liver revealed neoplastic cells occurring in loose groupings or lying singly, most of them with a spindle shape and elongated nucleus with the characteristic "salt and pepper" chromatin pattern of a neuroendocrine tumor. Cytoplasmic dendritic processes and intranuclear inclusions were frequently seen. The cytomorphologic features of the tumor were essentially the same as those of the primary MTC. Immunoreactivity for calcitonin confirmed the diagnosis.
  
  
  CONCLUSIONS
  In fine needle aspiration biopsy of liver masses, knowledge of the spindle pattern of the NT is important in order to achieve a correct diagnosis when metastases are the first manifestation of an occult primary tumor. Among neuroendocrine tumors, MTC must be included in the differential diagnosis.
authors.affiliation: Department of Pathology, Hospital 12 de Octubre, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Ibarrola de Andrés
authors.forename: V M
authors.initials: VM
authors.lastname: Castellano Megías
authors.forename: C
authors.initials: C
authors.lastname: Ballestin Carcavilla
authors.forename: N
authors.initials: N
authors.lastname: Alberti Masgrau
authors.forename: A
authors.initials: A
authors.lastname: Perez Barrios
authors.forename: P A
authors.initials: PA
authors.lastname: De Agustín
mesh_terms: D001707:Biopsy, Needle / Q000379:methods; D002116:Calcitonin / Q000032:analysis; D018276:Carcinoma, Medullary / Q000556:secondary* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000737:chemistry / Q000556:secondary*; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery
chemical_list: D002116:Calcitonin