Cytokeratin 19 immunolocalization in cell block preparation of thyroid aspirates. An adjunct to fine-needle aspiration diagnosis of papillary thyroid carcinoma.

Abstract

CONTEXT:

Immunohistochemical staining for cytokeratin 19 (CK-19) is a useful ancillary technique for diagnosing papillary thyroid carcinoma (papillary carcinoma) in histologic specimens. Although similar results have been obtained on aspirate smears, to our knowledge the utility of CK-19 immunolocalization in cell block preparations as an adjunct to fine-needle aspiration diagnosis of papillary carcinoma has not been examined.

OBJECTIVE:

The purpose of this study was to determine whether CK-19 immunostaining of cell block preparations of thyroid aspirates is a useful ancillary technique for diagnosing papillary carcinoma.

MATERIALS AND METHODS:

Using a monoclonal antibody to CK-19 and a standard avidin-biotin complex technique, immunostaining was performed on paraffin-embedded cell blocks of 57 cases with the following cytologic diagnoses: (a) papillary carcinoma (20 cases); (b) atypical cytology, cannot exclude papillary carcinoma (19 cases); and (c) nonneoplastic thyroid (18 cases). The staining reaction in each case was graded on the basis of percentage of epithelial cells stained (1+, <10%; 2+, <10%-50%; 3+, >50). Tissue follow-up was available in all cases.

RESULTS:

Nineteen (95%) of 20 cases with an unequivocal diagnosis of papillary carcinoma were positive for CK-19 (3+). Tissue follow-up confirmed papillary carcinoma in all 20 cases. Of the 19 cases with a diagnosis of atypical cytology, cannot exclude papillary carcinoma, 7 (37%) cases displayed 3+ immunostaining and subsequent excision confirmed papillary carcinoma in all 7 cases. The remaining 12 cases with 1+ immunostaining included surgically confirmed goiter (6 cases), adenoma (2 cases), lymphocytic thyroiditis (3 cases), and papillary carcinoma (1 case). The follicular cells in 18 cases with a cytologic diagnosis of nonneoplastic thyroid showed 1+ immunostaining. Histologic follow-up of these cases confirmed the nonneoplastic cytologic diagnoses.

CONCLUSIONS:

Cytokeratin 19 immunostaining of cell block preparations of thyroid aspirates serves as a useful tool for the diagnosis of papillary carcinoma. Strong immunostaining (3+) for CK-19 aids in accurate diagnosis of malignancy in cytomorphologically equivocal cases of papillary carcinoma.

• Authors: Kamal K Khurana, Luan D Truong, Virginia A LiVolsi, Zubair W Baloch
• Journal: Archives of pathology & laboratory medicine (Arch Pathol Lab Med) Vol. 127 Issue 5 Pg. 579-83 (May 2003) ISSN: 1543-2165 [Electronic] United States
• PMID: 12708901 (Publication Type: Comparative Study, Journal Article, Multicenter Study)

Chemical References

• Keratins

Topics

• Biopsy, Needle
• Carcinoma, Papillary (diagnosis)
• Cytodiagnosis (methods, statistics & numerical data)
• Epithelial Cells (pathology)
• Humans
• Immunohistochemistry (methods, statistics & numerical data)
• Keratins (immunology, metabolism)
• Paraffin Embedding (methods)
• Retrospective Studies
• Staining and Labeling (methods)
• Thyroid Neoplasms (chemistry, diagnosis)
• Thyroid Nodule (chemistry, pathology)
• Tissue Fixation (methods)