title: Hyalinizing trabecular adenoma--an uncommon thyroid tumor frequently misdiagnosed as papillary or medullary thyroid carcinoma.
abstract: BACKGROUND
  Hyalinizing trabecular adenoma (HTA) is an uncommon benign thyroid tumor that can present as a solitary thyroid nodule, a prominent nodule in a multinodular goiter, or as an incidental finding in a thyroidectomy specimen. The clinical significance of the lesion is that it is frequently misdiagnosed as papillary carcinoma on fine-needle aspiration cytology or as papillary or medullary carcinoma on histopathological section. We reviewed our recent experience with 7 patients diagnosed with HTA.
  
  
  METHODS
  Fine-needle aspiration biopsy was performed in 7 patients presenting with a solitary thyroid nodule (n = 4) or a multinodular goiter (n = 3). The patients underwent total thyroidectomy (n = 6) or hemithyroidectomy (n = 1).
  
  
  RESULTS
  In 4 patients, the preoperative cytology was suggestive of papillary carcinoma, in 2 patients suspicious, and in 1 patient positive for papillary carcinoma. On histopathological section, 2 patients had a microscopic HTA, 2 patients had HTA in 1 or 2 nodules of a multinodular goiter, and 3 patients had HTA in a solitary nodule. Except in 1 patient, who had a microscopic focus (3.2 mm) of papillary carcinoma, there was no evidence of malignancy in the surgical specimens on permanent histopathological section.
  
  
  CONCLUSIONS
  Although HTA is a rare condition of the thyroid, the surgeon needs to be aware of this entity to be able to better discuss the pathological findings with the patient, particularly since some pathologists and endocrinologists believe that HTA may represent a malignant neoplasm of low metastatic potential.
authors.affiliation: Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Evenson
authors.forename: Peter
authors.initials: P
authors.lastname: Mowschenson
authors.forename: Helen
authors.initials: H
authors.lastname: Wang
authors.forename: James
authors.initials: J
authors.lastname: Connolly
authors.forename: Savvas
authors.initials: S
authors.lastname: Mendrinos
authors.forename: Sareh
authors.initials: S
authors.lastname: Parangi
authors.forename: Per-Olof
authors.initials: PO
authors.lastname: Hasselgren
mesh_terms: D000236:Adenoma / Q000473:pathology* / Q000601:surgery; D000368:Aged; D044963:Biopsy, Fine-Needle; D018276:Carcinoma, Medullary / Q000175:diagnosis; D002291:Carcinoma, Papillary / Q000175:diagnosis; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy