In Reply.—We read with interest the letter by Kenneth Frankel, MD, in reference to our paper “Solid thyroid follicular nodules with longitudinal nuclear grooves.”1  We thank Dr Frankel for his interest in our publication and for his very thoughtful and pertinent questions. He asks 3 specific questions that we would like to respond to separately.

First, the author points out that the features illustrated in our paper include fine nuclear chromatin, nuclear folding, prominent micronucleoli, and oval shapes, which would qualify by cytology for a Bethesda category V diagnosis, and he asks whether we would recommend including this entity along with noninvasive follicular thyroid neoplasm with papillary features (NIFTP) in the Bethesda commentary for false-positive diagnosis of papillary carcinoma. The answer is yes, these cytologic features have the potential for confusion with papillary thyroid carcinoma (PTC) by cytology and should be considered as a potential cause of false-positive fine-needle aspiration (FNA) cytology. But this begs a more pragmatic question: How often should we expect to find these lesions in FNA cytology? As stated in our paper, most of the lesions were small and less than 1 cm in greatest diameter and were identified incidentally in specimens resected for other causes. Unlike in NIFTP, the likelihood that such lesions will become clinically apparent and specifically targeted for FNA is thus quite minimal.

Dr Frankel also asks whether we would recommend treating these lesions differently from those with a diagnosis of micropapillary carcinoma. As stated in our paper, we believe these lesions should be treated conservatively because of their indolent behavior. Given that in most of our cases they were incidental findings in lobectomy or thyroidectomy specimens removed for other reasons, we favor a simple follow-up and clinical observation rather than offering additional treatment.

Finally, the author asks whether “pragmatically, does the diagnosis of ‘follicular nodule with longitudinal nuclear grooves' make a difference in patient care?” We believe the answer is yes. Most of the cases in our study were referred in consultation for the suspicion of PTC and with the question of “rule out PTC.” We believe it would have been a disservice to these patients had they received a diagnosis of PTC given the indolent clinical behavior of these nodules and because of the potential implications for treatment. The point of the study was to alert pathologists to this unusual lesion that has the potential for being confused for PTC and to share our experience with long-term follow-up, which showed an indolent clinical behavior. We understand that similar lesions, like micropapillary thyroid carcinoma and even conventional PTC, can also frequently show an indolent clinical behavior; however, the label of “carcinoma” for such lesions always implies the possibility for additional treatment, not to mention the psychologic burden of a cancer diagnosis. For this reason, we feel it is appropriate to segregate this entity from PTC. One of the messages of the study, we believe, is “not everything with longitudinal nuclear grooves is necessarily PTC.”

Solid thyroid follicular nodules with longitudinal nuclear grooves: clinicopathologic, immunohistochemical, and molecular genetic study of 18 cases
Arch Pathol Lab Med

Author notes

The author has no relevant financial interest in the products or companies described in this article.