title: Use of immunohistochemistry in fine needle aspiration of thyroid nodules in patients with a history of malignancy. A report of two cases.
abstract: BACKGROUND
  A history of a nonthyroid malignancy may present a diagnostic dilemma in the assessment of fine needle aspiration (FNA) of thyroid nodules. One reported series, on patients with prior malignancies and a thyroid nodule, indicated that in 17% of patients, the thyroid nodule represented metastatic malignancy, 6% were classified as primary thyroid cancers, and the remainder were benign or inconclusive lesions. The resolution of this problem is essential to patient management.
  
  
  METHODS
  We report two cases in which patients with a history of renal cell carcinoma presented with a thyroid nodule. The first patient was an 80-year-old female whose Papanicolaou-stained FNA demonstrated clusters of round to polygonal cells with round to ovoid, hyperchromatic nuclei and abundant, wispy cytoplasm. The second patient was a 55-year-old female with clusters and single cells with round to oval, eccentric nuclei and copious, granular, gray cytoplasm noted on Papanicolaou-stained material. In each case, the diagnosis was inconclusive on initial review of Papanicolaou-stained slides, and immunohistochemical staining was ordered to better characterize the lesions. Tumor cells from case 1 were positive for cytokeratin cocktail and vimentin and negative for thyroglobulin, epithelial membrane antigen and calcitonin, suggestive of metastatic renal cell carcinoma. In contrast, the tumor cells from case 2 expressed cytokeratin, thyroglobulin and vimentin, consistent with a primary thyroid neoplasm. In each case, the cytologic diagnoses were confirmed in the resected specimens.
  
  
  CONCLUSIONS
  Immunohistochemistry is a helpful adjunct in the evaluation of thyroid nodules in patients with a past history of malignancy.
authors.affiliation: Department of Pathology, Ohio State University Medical Center, Columbus 43210, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Porcell
authors.forename: C L
authors.initials: CL
authors.lastname: Hitchcock
authors.forename: S
authors.initials: S
authors.lastname: Keyhani-Rofagha
mesh_terms: D000231:Adenocarcinoma, Papillary / Q000556:secondary*; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000556:secondary*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000473:pathology*; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology / Q000556:secondary*; D016606:Thyroid Nodule / Q000473:pathology*