In Reply. —
The letter by O'Leary and Walker raises several important issues concerning the natural history and management of thyroid carcinoma, particularly papillary carcinoma that presents as a cystic lesion. I agree with the authors' assertion that very small papillary thyroid carcinomas generally are not a threat to survival and that purposefully seeking them out and treating them makes little sense from a risk-benefit standpoint. The new World Health Organization classification of thyroid tumors has replaced the term occult papillary carcinoma with papillary microcarcinoma, a designation that applies to tumors 1 cm or less in diameter.1 There is good clinical evidence that these lesions have low potential for distant metastases and almost never result in cancer mortality.2,3 Nonetheless, a few papillary tumors smaller than 1 cm are locally invasive, which is a worrisome prognostic feature. Allo et al4 reported six papillary tumors smaller than 1.5 cm