Purpose: To describe the clinical characteristics and outcomes of patients with cytologically Bethesda IV category (B IV) thyroid nodules who opted for active surveillance.
Materials and methods: 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.
Results: 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.
Conclusions: 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.
Keywords: Active surveillance; Bethesda IV; FN/SFN; Follicular neoplasia; Indeterminate thyroid nodules; Low risk papillary thyroid carcinoma.