Diagnosis of papillary thyroid carcinoma in fine needle aspiration smears: factors that affect decision making.

OBJECTIVE

To investigate into the limitations in decision making in papillary thyroid carcinoma (PTC) in fine needle aspiration smears.

STUDY DESIGN

We studied the cytology reports of 21 cases with definitive diagnoses of PTC, 17 suspicious/suggestive of (S/O) PTC, and 17 rule out (R/O) PTC, 8 R/O neoplasms and 15 nonneoplastic lesions with 1 or more cytologic features of PTC. Five important cytomorphologic features-papillary formation, intranuclear cytoplasmic inclusions, nuclear grooves, fine nuclear chromatin and psammoma bodies--were analyzed for their frequency and through a scoring system.

RESULTS

Three or more cytologic features of PTC were present in 18 (85.7%) cases with a definitive diagnosis of PTC as opposed to 7 (41.2%) cases diagnosed as S/O PTC, 2 (11.8%) of R/O PTC, 0% of R/O neoplasia and 0% of nonneoplastic lesions (p =0.0062-<0.0001). The scores of PTC cases (5.8+/-1.14) were significantly higher (p <0.0001) than those of S/O PTC (3.8+/-1.47), R/O PTC (2.4+/-1.27), R/O neoplasia (1.4+/-0.69) and nonneoplastic lesions (1.1+/-0.62). Available histopathology reports in PTC, S/O PTC and R/O PTC cases confirmed the presence of PTC in 92.9%, 62.5% and 16.7%, respectively.

CONCLUSION

During decision making, the number of cytomorphologic features as well as some specific features and their extent in FNA smears give varying amounts of confidence to the cytopathologist in diagnosing the cases as PTC or otherwise.