Fine-Needle Aspiration of Papillary Thyroid Carcinoma: Distinguishing Between Cases That Performed Well and Those That Performed Poorly in the College of American Pathologists Nongynecologic Cytology Program

Context.—Although the cytologic features of papillary thyroid carcinoma in fine-needle aspiration specimens are well known, the correlation of these features with the ability of cytologists to identify this tumor has not been well studied. Objective.—To compare the cytologic features of cases of papillary thyroid carcinoma that performed poorly with those of cases that performed well. Design.—The cytologic features of 13 cases of papillary thyroid carcinoma from the College of American Pathologists Nongynecologic Cytology Program that performed poorly were compared with those of 15 cases that performed well. Results.—Compared with cases that performed well, cases that performed poorly were significantly more likely to lack marked nuclear enlargement (38% vs 100%, P < .001), lack pale chromatin (8% vs 47%, P = .04), and lack intranuclear inclusions (8% vs 53%, P = .02). The differences between the 2 groups in staining, type of preparation, nuclear grooves, nuclear crowding, colloid, cellularity, nuclear pleomorphism, and Hurthle cell change were not significant. Conclusions.—Cases of papillary thyroid carcinoma that lack marked nuclear enlargement, pale chromatin, and intranuclear inclusions are significantly more difficult to recognize than cases that have these features. Increased awareness of these types of cases might improve the performance of thyroid fine-needle aspiration in clinical practice.