Active surveillance in small cytological indeterminate thyroid nodules: a call to common sense?

To describe the clinical characteristics and outcomes of patients with cytologically Bethesda IV category (B IV) thyroid nodules who opted for active surveillance.

We prospectively evaluated 155 patients with a single thyroid nodule classified as B IV. Immediate molecular testing and/or thyroid surgery was offered, except when the patient (i) could not afford molecular testing/rejected the surgery, (ii) had a high surgical risk, (iii) had other disorders/comorbidities which needed to be addressed with higher priority, and (iv) had undetectable serum calcitonin levels, in whom active surveillance (AS) was performed.

From 155 patients, only two patients could afford molecular testing; 84% (n = 130) underwent immediate thyroid surgery: lobectomy was performed in only 8% (n = 10). AS was the initial management for 15% (n = 23) of the patients. The frequency of tumor enlargement was 14% (n = 3), after a median of 42 months (range, 7-72) of follow-up, without any evidence of lymph node or clinical distant metastases development. Deferred surgery was performed in 4 patients (17%) after a median of 24 months (range, 12-48) of AS. Follicular adenoma was diagnosed in three and a follicular variant of papillary thyroid carcinoma in one patient, all of them without evidence of disease after 12 months of follow-up.

Despite current guidelines does not support AS for indeterminate Bethesda IV nodules, our findings showed that most of these patients had excellent outcomes, in a setting where lobectomy was not the preference and the access to molecular testing was limited. Probably AS could be a valid alternative in these low-risk tumors in selected patients.