Response to Letter to the Editor From Devgan and Mayilvaganan: “Natural History and Predictive Factors of Outcome in Medullary Thyroid Microcarcinoma”

To the Editor,

We thank Dr. Yuvraj Devgan and Dr. Sabaretnam Mayilvaganan for their interest in our paper and agree that the literature regarding outcomes of medullary thyroid microcarcinoma is varied (1, 2). We believe that incidental medullary thyroid microcarcinomas are being diagnosed more commonly now. Rather than reflecting a true increase in the incidence of the tumor, we think this probably reflects increased pathological sampling of thyroids removed for other reasons and a lower threshold for ultrasound investigation and biopsy in community practice. There is a risk of both “overdiagnosis” and “overtreatment” of these small commonly incidental and asymptomatic tumors, and older publications may not fully reflect the modern experience. In this context, we are glad to be able to add to the literature and demonstrate that tumor grade can be a useful marker for prognosis (1).

In response to Dr. Devgan's and Dr. Mayilvaganan's queries:

1. The preoperative diagnosis of medullary thyroid cancer (MTC) was established in 5 patients through fine needle aspiration biopsy (FNAB) of a suspicious thyroid nodule. For these patients, the MTC size ranged from 6 to 10 mm. Although we do not routinely recommend biopsy of subcentimeter lesions, in practice we are often are referred patients who have already undergone FNAB of thyroid nodules based on suspicious ultrasound features. In 1 patient, the preoperative diagnosis was made after FNAB of a suspicious lateral neck lymph node.

2. Regarding the preoperative calcitonin measurement, it is our practice to routinely perform preoperative calcitonin for patients with a diagnosis of MTC. In this series a preoperative calcitonin level was available in our database for only 3 of the 6 patients with a preoperative MTC diagnosis, all of whom had a level of above 200 pg/mL. However, due to the small sample size, we have not performed further analysis.

3. Regarding the 4 patients treated with hemithyroidectomy alone, median follow-up was 4 years. All of these patients had low-grade tumors and remained disease free, with normal clinical exam and imaging and a calcitonin of less than 5 pg/mL.

Disclosures

The authors have nothing to disclose.

References