Clinical and cytopathological features of suspected thyroglossal duct cysts and neoplasms arising from them: A large series from a referral cancer center

Background: Thyroglossal duct cysts (TGDCs) are the most common congenital midline cystic lesions in the neck, and they are often evaluated by fine-needle aspiration. Recognizing the cytomorphologic features of TGDCs and their mimics is important for clinical management. Methods: This study examined the clinical, radiological, and cytopathological features of 86 ultrasonography-guided fine-needle aspiration (US-FNA) specimens from clinically suspected TGDCs or malignancies arising from TGDCs and correlated the findings with surgical follow-up and/or imaging studies. Results: According to ultrasound examinations of 66 lesions, 17 (25.8%) were cystic, 8 (12.1%) were cystic with septations, 21 (31.8%) were cystic with solid nodules, and 20 (30.3%) were solid or cystic with internal debris. Cytopathologically, 81 lesions (94%) were categorized as benign, 2 (2%) were categorized as atypical, and 3 (3%) were categorized as malignant. In benign lesions, proteinaceous material (63%), histiocytes (63%), colloid (37%), squamous cells (35%), columnar cells (32%), follicular cells (15%), inflammatory cells (9%), and multinucleated giant cells (9%) were noted. Diagnoses in the benign category included TGDC in 64 patients (75%), TGDC or mimics (colloid nodule/epidermoid cyst) in 14 patients (17%), a colloid nodule in 1 patient, and thyroiditis in 1 patient. Surgical resection, performed in 23 patients, confirmed TGDCs in 12, benign mimics in 7, and carcinoma in 4. Conclusions: Cytopathological features, in conjunction with imaging, allowed a definite diagnosis of TGDC in most patients (75%). The presence of mature squamous cells, thyroid follicular cells, with or without colloid and/or lymphocytes alone allowed a differential diagnosis of TGDC and its mimics in 17%. US-FNA findings could not distinguish primary carcinomas arising from TGDCs from metastatic tumors.