<p>I have topographically analysed the kinetic features [proliferation by Ki67 index and apoptosis by in situ end labelling (ISEL) or ISEL index] of follicular thyroid neoplasms (43 FTA, 76 FTC—including 28 minimally invasive and 48 widely invasive—and 27 anaplastic carcinomas) and have obtained similar results. Apart from the diagnostic applicability, these results provide insight into the basis of the known architectural patterns of thyroid tumours.</p>
<p>The Ki67⁄ ISEL indices provide kinetic advantage in the internal compartments of benign lesions and in the peripheral compartments of malignant lesions. Benign lesions (FTA) and low-grade malignancies (minimally invasive FTC) show higher rates of apoptosis in peripheral compared with internal compartments, whereas high-grade malignancies (widely invasive FTC and anaplastic thyroid carcinoma) reveal the inverse relationship.</p>
<p>Conclusion: Differential cell kinetics in follicular thyroid neoplasms contributes to a topographical segregation of tumour cells and the growth pattern (encapsulation and invasiveness at the tumour periphery).</p
