Correlation between cytological and histological findings in patients who underwent thyroidetomy.Predictive value and confounders

BACKGROUND: Solitary thyroid nodules are the most common endocrine occurance in general population. With the introduction of Bethesda system for reporting thyroid cytopathology (BSRTC) to fine-needle aspiration (FNA) specimens we found a reliable standard method to evaluate malignancy risk in thyroid neoplasms. This study evaluates the correlation between BSRTC and real results in our center investigating the role of several factors as confounding factors for cytological diagnosis. The study has been designed as a retrospective study conducted on 637 patients that underwent thyroid surgery in a single center (Unit of General Surgery, Parma University Hospital, Italy). METHODS: We reviewed 637 files of patients who underwent thyroid surgery with a definitive histological finding from surgical specimen. The collected data include: cytological findings from FNA when performed, histological findings after surgery, sex, age, thyroid hyperfunction and the possible presence of thyroiditis. Cytological findings have been evaluated from our institution's pathologists after FNA performed in collaboration with clinical endocrinologists. Thyroid Hyperfunction has been evaluated through a blood test panel for thyroid functionality including reflex TSH, FT3, FT4 and thyreoglobulin. Blood tests' results and patients have been evaluated by clinical endocrinologists before being addressed to surgery. Thyroiditis have been confirmed as an ultrasound scanning (US) finding or as a corollary from histologic results. All patients have been evaluated by the surgeon and underwent different intervention as total, thyroidectomy, near total thyroidectomy or emithyroidectomy depending on cythology, US findings and symptoms in case of benignancy. Histological findings have been evaluated only by our center pathologists. RESULTS: In our experience the percentage of malignancy in Thyr 2 Thyr 3 and Thyr 4 Bethesda's classes seeems to be higher then those predicted by BSRTC. We also found a high rate of false positive considered as patients included in categories of suspected malignancy (Thyr 3-4-5-6) and subsequently resulted with benign pathology. This happens specially in those patients affected by thyroiditis. CONCLUSIONS: These findings suggest that we need more studies to evaluate real BSRTC predictive value in single centers. Meanwhile we found out that thyroiditis may be a confounding factor in cytological examination wich would lead to an overstating of thyroid nodules.