Differential diagnosis of oncocytic lesions of the breast and thyroid utilizing a semiquantitative approach

OBJECTIVE: To assess whether a light microscopic, semiquantitative approach could reliably distinguish between benign nonneoplastic, benign neoplastic and malignant oncocytic lesions of the breast and thyroid. STUDY DESIGN: Alcohol-fixed, Papanicolaou-stained fine needle aspiration sm ears of histologically proven goiter and chronic thyroiditis (18 cases), Hu rthle cell adenomas (7 cases), Hurthle cell carcinomas (ii cases),fibrocyst ic disease (17 cases), papillomas and papillomatosis (7 cases) and apocrine carcinomas (6 cases) were rated by three independent observers using the f ollowing 10 cytologic criteria: cellularity, nuclear-cytoplasmic ratio, mul tinucleation, nuclear size, nuclear shape, anisonucleosis, multinucleolatio n, nucleolar-nuclear ratio, nucleolar size and nucleolar shape. Each of the se 10 cytologic criteria was rated using a 1-3 scale. The scores for all 10 features were summed to give a total score for each case. The total scores were statistically analyzed to determine the validity and reproducibility of the summed criteria. RESULTS: The summed criteria of the total scores were reproducible between the three observers, with standard deviations ranging from 1.36 to 2.88 for thyroid and 1.72 to 2.00 for breast oncocytic lesions. The ability of the total scores to differentiate benign from malignant oncocytic lesions of th e breast and thyroid was confirmed by a positive predictive value for malig nancy of 67% for thyroid and 72% for breast and a negative predictive value for malignancy of 100% for nonneoplastic oncocytic lesions and > 90% for b enign oncocytic neoplasms in both. The Kruskal-Wallis test revealed that th e total scores were able to distinguish three diagnostic categories of nonn eoplastic, benign neoplastic and malignant oncocytic breast and thyroid les ions, with P < .005. CONCLUSION: Without the expenditures of additional time, costs or materials , this semiquantitative approach compared favorably with contemporary morph ometric studies involving the differential diagnosis of oncocytic cell path ology in fine needle aspiration cytology.