Diagnostic value of qualitative and quantitative variables in thyroid lesions

Two hundred and thirty-three thyroid lesions were studied by fine needle as piration (FNA) cytology using standard cytologic criteria available in the literature. These included 114 cases of nodular colloid goitre (NCG), 47 ca ses of Hashimoto's thyroiditis (HT), 12 follicular adenomas (FAd), five cas es of subacute thyroiditis and three cases of thyrotoxicosis among the beni gn lesions. The malignant lesions seen were 30 cases of papillary carcinoma (PCa), 16 follicular carcinomas (FCa), three cases with double lesions, e. g. papillary carcinoma with coexisting NCG, and three of papillary carcinom a with HT. Emphasis was given to eight qualitative and quantitative (morpho metric) variables in these various thyroid lesions. Cell measurements were done using a Visopan Lux projection microscope. The three qualitative varia bles included type of nuclear membrane (regular/irregular), type of nuclear chromatin and the presence or absence of conspicuous nucleoli. The quantit ative variables studied were nuclear diameter, nuclear area, cytoplasmic di ameter, cytoplasmic area & N/C ratio. Statistical analysis was performed in order to know whether the standard cytologic criteria used at FNA cytology in the literature (increased cellularity, microfollicles, increased N/C ra tio, absence of significant haemosiderin-laden macrophages and scanty collo id) could differentiate a follicular adenoma from a follicular carcinoma. A statistical analysis was also performed to establish the utility of the qu alitative and quantitative variables. The results showed that none of the s tandard cytologic criteria applied could differentiate follicular adenoma f rom a follicular carcinoma. With regard to qualitative variables, irregular ity of nuclear membrane and presence of conspicuous nucleoli were most sign ificant in papillary carcinoma, followed by follicular carcinoma, then by f ollicular adenoma; these features being hardly evident in nodular colloid g oitre and Hashimoto's thyroiditis. A coarse nuclear chromatin was most sign ificant in follicular carcinomas followed by follicular adenomas. It was le ss obvious in the benign conditions, but more prominent in Hashimoto's thyr oiditis compared with a goitre. It was also not obvious in a papillary carc inoma. Of the quantitative variables, all measurements were greatest in PCa > FCa > FAd > NCG = HT. When differentiating follicular adenoma from folli cular carcinoma the qualitative variables of significance were the presence or absence of nucleoli, the chromatin pattern and regularity/irregularity of nuclear membrane; the nuclear area was the most important feature among quantitative variables.