Follicular and Hürthle cell lesions of the thyroid: can inconclusive results be minimized?

ABSTRACT

OBJECTIVE: To assess the cytologic criteria for distinguishing neoplastic from nonneoplastic follicular cell and Hürthle cell thyroid lesions. STUDY DESIGN: Ten previously described and commonly used cytologic criteria were evaluated and graded on a 0-4 scale in a consecutive series of thyroid fine needle aspirations (FNAs) reported as follicular or Hürthle cell neoplasms or lesions. Scoring was compared to subsequent surgical outcome. RESULTS: A total of 93 (57fo llicular cell and 36 Hühle cell) cases was analyzed. No individual cytologic feature was helpful in distinguishing benign neoplarms from malignancy in either category (p > 0.05), but 4 or more coexistent cytologic features in combination were identified in 50.0% of follicular neoplasms, 13.6% of Hürthle cell neoplasms and none of the nonneoplastic lesions. An unexpected number (13 of 93, 14.0%) of unrecognized papillary carcinomas, some of follicular subtype, was encountered. CONCLUSION: In this series, the indeterminate thyroid FNA category could have been reduced by diagnosis of samples with 4 or more of the studied criteria as definite follicular (50% of cases) or Hürthle cell (13.6% of cases) neoplasms and by more astute recognition of papillary carcinomas (14.0% of cases), which blend into this category, often as a result of less-than-optimal sampling or preservation.