Neck Schwannoma Masking as Thyroid Tumour: Into the Deep of Diagnostics and Anatomy

Schwannomas are benign nerve sheath tumours that exhibit a slow rate of growth. In the vast majority of cases, schwannomas manifest as asymptomatic masses. The presence of symptomatic lesions may necessitate surgical removal. The incidence of schwannomas ranges from 4.4 to 5.23 cases per 100,000 population, accounting for approximately 7% of all primary tumours in the central nervous system. There is a limited number of case reports describing schwannomas outside the central nervous system. In rare instances, schwannomas may originate at the level of the thyroid gland. In such cases, incidental neck schwannomas may be mistaken for thyroid or parathyroid tumours. The increasing incidence of thyroid cancer draws more attention to all thyroid nodules, both benign and malignant. Thyroid nodules are detected in up to 65% of autopsies, with only 4-6.5% being malignant. Thyroid tumours are typically diagnosed by USG; however, they are often revealed incidentally during neck CT or MRI for other conditions. To rule out malignancy, tumour verification is required. The modern diagnosis of thyroid cancer is based on fine-needle aspiration (FNA) biopsy and cytology, which is classified according to the Bethesda classification system. However, not all FNAs are informative, and the differential diagnosis and treatment strategies in cases of unsatisfactory results are not standardized, leading to potential intraoperative challenges. We present a case study of a patient with a thyroid nodule that was ultimately diagnosed with a schwannoma of the neck according to core-needle biopsy.