Cell size as a prognostic factor in oncocytic poorly differentiated carcinomas of the thyroid.

Histological and cytological criteria in predicting clinical outcomes in patients with oncocytic poorly differentiated carcinoma (PDC) of the thyroid were investigated. In a set of 102 PDC patients, we performed a computer-assisted evaluation of cell size based on two different methods. Univariate analysis showed that cell size was a discriminant prognostic parameter in oncocytic PDC (30 cases) but not in the non-oncocytic carcinoma cases (72 cases). Patients with oncocytic PDC with small-medium cell size had a significantly increased risk of death (P = .029) and a decrease of disease-free survival (P = .014). This correlation was absent in cases of non-oncocytic PDC, where age and extensive vascular invasion were significant indicators of progression. The proposed morphological signature shows a robust discriminatory ability when tested on the oncocytic PDC group, and cell size assessment could thus be proposed as an inexpensive and readily evaluable parameter for predicting prognosis and planning therapy in this tumor type.