Papillary and follicular neoplasms of the thyroid gland. Differential immunohistochemical staining with high-molecular-weight keratin and involucrin.
The morphologic distinction between papillary and follicular neoplasms of the thyroid gland can be difficult, especially on small biopsy specimens or in fine-needle aspirations. To determine whether immunohistochemistry could help in achieving the correct diagnosis, we characterized the staining pattern for a series of papillary and follicular neoplasms of the thyroid gland. A pilot study was performed using a panel of antibodies, including high-molecular-weight keratin (HMWK, 34 beta E12), cytokeratin (CK) 5/6, CK7, CK13, CK14, CK20, AE1/AE3, CAM5.2, involucrin, and villin. Of these antibodies, involucrin and HMWK showed strong differential staining between follicular and papillary neoplasms. HMWK stained 91% of papillary carcinomas, including follicular variants, with a median of 53% positive cells, and involucrin stained 72.5% of papillary neoplasms with a median of 45% positive cells. HMWK stained only 20% of follicular neoplasms, whereas involucrin stained 29% of cases. Papillary neoplasms showed strong, although patchy, staining with HMWK and involucrin, whereas those follicular neoplasms that did have staining showed a weak, diffuse pattern of staining. We believe that HMWK, and involucrin to a lesser degree, could be useful in differentiating papillary from follicular neoplasms, especially for cytologic cell block material or for cases in which the architectural pattern is follicular.
Liberman
E
E
Department of Pathology, Seton Medical Center, South San Francisco, California, USA.
Weidner
N
N
D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism; D002291:Carcinoma, Papillary / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D018265:Carcinoma, Papillary, Follicular / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology
D014408:Biomarkers, Tumor; D011498:Protein Precursors; C032253:involucrin; D007633:Keratins