[Cyto-histological correlation of malignant thyroid nodules: clinical factors as predictors of malignancy]

Fine-needle aspiration (FNA) is routinely used to distinguish benign from malignant tumors in thyroid nodules. Most benign or malignant diagnosis are confirmed by histology, but for suspected malignancies (Follicular neoplasm and Hürthle-cell neoplasm histology is always required. Some clinical factors have been identified as predictors of malignancy in the suspicious cases with eventual interest for treatment options.

To determine the correlation between FNA and histological diagnosis in malignant tumors at Hospital de Egas Moniz. Identify factors that may influence the risk of malignancy in patients with suspected malignancies (Tumor size, gender and age group).

Retrospective study of patients with malignant or suspected malignant tumors diagnosed by FNA in the institution. All patients were subsequently diagnosed by histology and age, sex and tumor dimension were also recorded.

From 2685 FNA performed between October 1996 and June 2005, 68 patients were considered for analysis, which have been diagnosed as malignant (34 patients) or suspicious of malignancy (34 patients). Only in one case didn't the histology confirm the cytological diagnosis of malignancy. Among the suspicious FNA 25 were benign (23 female and 2 male, mean age of 54,3 +/-17 yo and mean nodule size of 2,8 +/- 1,8 cm) and nine (26,5%) were malignant (all female, mean age 68,3 +/- 13 yo and mean nodule size 2,67 +/- 1,5 cm). Nodules with 2 cm or more were malignant in 37% (vs 8% when < 2 cm; P=0,033) and patients with 50 yo or more revealed to be malignant in 33% (vs 10% when < 50 yo; P=0,019), therefore nodule size and age were identified as independent predictors for malignancy.

There was a strong correlation between cytological and histological diagnoses. Age and tumor size were strong predictors of malignancy in patients with suspected malignancies. This and other factors may be useful to identify patients who may benefit from a total thyroidectomy as the first intervention.