Cytokeratin 19 immunoreactivity in the diagnosis of papillary thyroid carcinoma: a note of caution.

TitleCytokeratin 19 immunoreactivity in the diagnosis of papillary thyroid carcinoma: a note of caution.
Publication TypeJournal Article
Year of Publication2001
AuthorsSahoo S, Hoda SA, Rosai J, DeLellis RA
JournalAm J Clin Pathol
Date Published2001 Nov
KeywordsAdenoma, Biomarkers, Tumor, Carcinoma, Papillary, Cell Count, Diagnosis, Differential, Humans, Immunoenzyme Techniques, Keratins, Pathology, Thyroid Gland, Thyroid Neoplasms, Thyroid Nodule

To evaluate the expression of cytokeratin (CK) 19, we stained sections obtained from formalin-fixed, paraffin tissue blocks of 35 thyroid tumors (follicular adenoma [FA], 20; papillary thyroid carcinoma [PTC], 10 follicular variant [FV] and 5 usual type) and scored the extent of staining as follows: 1+ (<5% positively stained cells), 2+ (5%-25% positively stained cells), 3+ (25%-75% positively stained cells), and 4+ (>75% positively stained cells). All 15 PTCs (including 10 FV-PTCs) were CK19 positive: 14 were 4+ and 1 (FV-PTC) was 2+. All 20 FAs also were CK19 positive: 15 were 1+, 1 was 2+, 4 were 3+, and none was 4+. In the FAs that were scored 1+, reactivity usually was confined to follicular cells lining cystically dilated atrophic follicles that lacked the typical nuclear features of PTC. The remaining FAs showed more diffuse reactivity, which was, however, less intense than that observed in the PTCs. Thus, immunoreactivity for CK19 is not specific for PTC, although we acknowledge that the extent and intensity of staining are considerably greater in this tumor than in FA. There were no significant differences in staining for CK19 between nonneoplastic follicles adjacent to PTCs and those adjacent to FAs.

Alternate JournalAm J Clin Pathol
PubMed ID11710686
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