Title: Comparative Analysis of Clinical Outcomes in Tall Cell Variant Papillary Thyroid Microcarcinoma

Introduction: The clinical behaviour of tall cell papillary thyroid microcarcinomas (PTMCs) remains largely unexamined, especially within the Irish population. This study evaluates the differences in outcomes between tall cell PTMCs and those with less aggressive histological profiles.
Methods: A retrospective cohort study was conducted at St. James’s University Hospital, using head and neck cancer tumour board data from 2013 to 2023. Clinical, demographic, histopathological, and treatment data were collected. Recurrence-free and overall survival were analysed using the Kaplan-Meier method.
Results: Among 152 patients with T1a PTMC, 47 had non-incidentally detected disease, including 8 with tall cell pathology and 39 with classical/follicular subtypes. The mean age was 46.7 (16.6) years. No significant differences were observed in disease focality (p = 1.000), nodal positivity (p = 0.685) or mean foci size (p = 0.185). Outcomes, including complications (p = 0.548) and total thyroidectomy rates (p = 1.000) were also comparable. Recurrence rates showed no significant difference (p = 0.629).
Conclusions: Despite its association with poor prognosis, tall cell pathology in PTMC does not significantly impact outcomes. Patients with tall cell PTMCs have excellent survival, comparable to classical/follicular subtypes, and should be considered for general practitioner discharge.