title: Asymptomatic intrathyroidal parathyroid adenoma. Report of a case with a cytologic differential diagnosis including thyroid neoplasms.
abstract: BACKGROUND
  Intrathyroidal parathyroid neoplasms (IPNs) are uncommon tumors with an indolent clinical course. When asymptomatic, they can be incorrectly diagnosed as thyroid neoplasms on fine needle aspiration biopsy (FNAB), leading to inappropriate surgical treatment.
  
  
  METHODS
  A case of unsuspected IPN occurred in which the cytologic picture mimicked that of a thyroid neoplasm. The histologic specimen of the total thyroidectomy showed 2 adjacent intrathyroidal nodules morphologically and immunohistochemically corresponding to a parathyroid adenoma.
  
  
  CONCLUSIONS
  The incidence of IPN remains controversial, especially in asymptomatic patients. On FNAB it is a possible cause of inappropriate surgery for a suspicious thyroid neoplasm (follicular or medullary carcinoma). Immunostaining for parathormone on the cytologic smear is valuable in establishing the correct preoperative diagnosis when the morphologic features are strongly suggestive of IPN.
authors.affiliation: Division of Anatomic Pathology and Histology, Catholic University of the Sacred Heart, Largo Francesco Vito, 1, 00168 Rome, Italy.
authors.forename: Esther Diana
authors.initials: ED
authors.lastname: Rossi
authors.forename: Antonino
authors.initials: A
authors.lastname: Mulè
authors.forename: Gian Franco
authors.initials: GF
authors.lastname: Zannoni
authors.forename: Guido
authors.initials: G
authors.lastname: Fadda
mesh_terms: D000236:Adenoma / Q000473:pathology*; D044963:Biopsy, Fine-Needle; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000032:analysis; D010282:Parathyroid Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D013048:Specimen Handling / Q000379:methods; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000473:pathology; D013965:Thyroidectomy; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone