A Rare Entity: Papillary Thyroid Carcinoma with Squamous Differentiation Diagnosed in a Middle-aged Man Following Endoscopic Total Thyroidectomy via Axillo-Bilateral Breast Approach

Although squamous metaplasia is a well-known occurrence in papillary thyroid carcinoma (PTC), it is extremely uncommon to diagnose a PTC with squamous differentiation (PTC-SD), especially in a non-elderly patient, thus raising a diagnostic challenge when considering its broad histopathological differential diagnosis. Endoscopic thyroidectomy via axillo-bilateral breast approach (ABBA) has been recently validated as an appropriate surgical alternative to conventional thyroidectomy for treating PTC in the selected patients. Hereby, we report a rare case of PTC-SD diagnosed in a solitary thyroid nodule (STN) in a 30-year-old man with a family history of thyroid cancer who was operated using the endoscopic ABBA. In fact, detection of the squamous cell carcinoma component may not be feasible through fine needle aspiration cytology or frozen section examinations, while permanent paraffin sections and immunohistochemistry (if required) usually allows for its identification. Due to their diverse clinical and biological behaviors, it is important to differentiate PTC-SD from other conditions in which a thyroid specimen contains a squamous epithelium. PTCSD patients with favorable clinicopathological criteria as young age and localized disease can be fortunate candidates for the minimally invasive thyroidectomy approaches as endoscopic ABBA.