Background: PTEN hamartoma tumor syndrome (PHTS) is associated with a high prevalence and early onset of differentiated thyroid cancer and benign thyroid disease. However, a consensus on the time of initiation and frequency of thyroid cancer surveillance has not yet been reached. Most commonly, guidelines recommend annual thyroid ultrasounds, but vary widely in the time of initiation, ranging from shortly after birth to 18 years of age. Minimal data are available on the development and progression of thyroid disease over time in this population. This study aimed to target this knowledge gap by investigating the time to develop thyroid nodules and thyroid cancer from an initial ultrasound in 76 PHTS patients. Methods: The electronic records of 281 prospectively accrued PHTS patients were retrospectively reviewed between 2005 and 2021, and 76 patients were identified as having at least two thyroid ultrasounds. Time-to-event analyses were performed, determining the probability of developing thyroid nodules and thyroid cancer over time. Results: We demonstrated that PHTS patients with an initial thyroid ultrasound without nodules (n = 41) had >90% likelihood of remaining free of a clinically actionable nodule at 3 years and an 85% likelihood at 6 years. None of these patients developed thyroid cancer over the entire follow-up period (mean 4.6 years). In patients with a clinically nonactionable nodule, defined as not meeting criteria for fine needle aspiration or thyroidectomy (n = 14), we demonstrated that 80% will not have an actionable nodule at 3 years, and none developed thyroid cancer over the entire follow-up period. Conclusions: Our observations suggest stratifying surveillance intervals based on thyroid ultrasound result, and support extending surveillance intervals in PHTS patients without nodules on ultrasound to 3-5 years, and patients with clinically nonactionable nodules to 2-3 years, in contrast to the current recommendation of annual ultrasounds. This change in practice would decrease the burden of frequent ultrasounds, especially in young children and adolescents who are more likely to have a normal or nonactionable ultrasound result.

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