Contribution of transmission electron microscopy to fine-needle aspiration biopsy diagnosis : Comparison of cytology and combined cytology and transmission electron microscopy with final histological diagnosis

This report evaluates 74 fine-needle aspiration biopsies processed for transmission electron microscopy with subsequent surgical procedure. The specificity of diagnosis obtained by cytology alone was compared to that obtained by cytology and electron microscopy, using histologic diagnosis as the gold standard. When cytology gave a diagnosis of malignancy but could not give tumor category or type, electron microscopy could correctly give both. When cytology could give tumor category but not type, electron microscopy correctly identified type in the majority of cases. When cytology gave tumor category and type, electron microscopy confirmed the diagnosis. Transmission electron microscopy is very helpful when the cytopathologist can diagnose malignancy but cannot give tumor category and/or type. When the cytopathologist is specific in his/her diagnosis, TEM is not as helpful.