Diffuse Sclerosing Variant of Papillary Thyroid Carcinoma: A Single-Center Case Series of Five Patients

Background: Diffuse sclerosing variant papillary thyroid carcinoma (DSVPTC) is a rare subtype of papillary thyroid carcinoma characterized by diffuse intrathyroidal involvement and frequent cervical lymph node metastasis. This study aims to delineate the clinicopathologic features, treatment outcomes, and recurrence patterns of DSVPTC. Methods: We retrospectively reviewed five patients with histopathologically confirmed DSVPTC treated at Zibo Central Hospital between 2009 and 2025. Follow-up data were collected until December 30, 2025. Results: Patients were aged 22-54 years (median: 41 years) and 60% (3/5) were female. Hashimoto's thyroiditis was present in 80% (4/5). All patients presented with diffuse microcalcifications on ultrasound (100%, 5/5). Thyroid FNA was performed in 80% (4/5) and all aspirates were Bethesda category VI. Cervical lymph node metastasis was observed in all patients: central compartment in 100% (5/5) and lateral neck in 60% (3/5). TNM staging (8th edition) included: pT1aN1aM0 (n=1), pT1aN1bM0 (n=1), pT3bN1aM0 (n=1), pT3bN1bM0 (n=2). According to ATA risk stratification, 3 patients were classified as high risk and 2 as intermediate risk. All patients underwent total thyroidectomy with bilateral central neck dissection. Lateral neck dissection was performed in 3 patients with radiologic evidence of lateral nodal disease. All patients received TSH suppression therapy (TSH <0.1 mIU/L) and two courses of I-131 therapy (100 mCi per course) at 3 and 6 months postoperatively. With a median follow-up of 2 years (range: 1-16 years), structural recurrence occurred in 2 patients (40%, 2/5) in the ipsilateral lateral neck at 1 and 4 years, respectively. No distant metastasis or disease-specific death occurred. Conclusion: In this small series of five patients, DSVPTC commonly presented as a nodule-negative "snowstorm" microcalcification phenotype with high nodal burden. Despite aggressive multimodal therapy including total thyroidectomy, TSH suppression, and scheduled radioiodine, lateral neck recurrence occurred in 40% of patients. Meticulous preoperative lateral neck assessment and long-term imaging-based surveillance remain essential.