Electron microscopy of ultrasound-guided fine-needle biopsy specimens

A prospective 3-year study was undertaken in order to assess the value of electron microscopy (EM) as a supplement to routine light microscopy (LM) in ultrasound-guided fine-needle biopsy of suspected abdominal and retroperitoneal tumours. Eight-six of the 899 ultrasound-guided fine-needle biopsies performed during this period were supplemented with EM using the following indications: metastatic lesions with unknown primary tumour, primary retroperitoneal tumours, tumours with atypical clinical histories and where the primary LM evaluation was unable to determine tumour cell type. Two methods of obtaining material for EM were tested, namely, fine-needle aspiration and fine-needle histological biopsy (Surecut). Both methods yielded suitable material for EM evaluation in approximately 80% of the 76 cases where tumour cells were identified by LM. However, it was technically easier to process material for EM when obtained by fine-needle histological biopsy. The results of the 62 cases where suitable material for EM was obtained were grouped according to the histopathological and clinical value of the diagnosis. In 23 cases (37%) EM was without additional diagnostic value. In 12 cases (19%), EM supplied a more precise histopathological diagnosis, but the diagnostic gain was without clinical significance. In 27 cases (44%) EM was of significant clinical value, as the diagnosis by itself was enough to change the investigative procedure and/or the treatment of the patient.