ELECTRON-MICROSCOPIC EXAMINATION OF CYTOLOGIC SAMPLES

OBJECTIVE: To review the results of observations of cytologic samples performed in our laboratory by light microscopy (LM), scanning electro n microscopy (SEM) and transmission electron microscopy (TEM) performe d in succession (LM-SEA I-TEM examination) using the same cytologic sa mple and to assess the diagnostic value of this method of successive e xamination. STUDY DESIGN: Using a previously reported method of LM-SEM -TEM sample preparation and observation, we analyzed 201 cytologic spe cimens over a seven-year period (1986-1993) and investigated whether t he histologic origin and malignancy can be estimated from SEM and TEM findings on the cells. RESULTS: Observations of many cytologic samples over a seven-year period (by LM, SEM and TEM) showed that several bas ic interpretations of cellular ultrastructure are possible. In cases w here cell identification was difficult by LM, electron microscopic fin dings were sometimes useful for determining the biologic characteristi cs of cells and for estimating their tissue origin. Electron microscop ic findings also provided important information for cytodiagnosis. CON CLUSION: SEM and/or TEM findings are useful for determining the morpho logic (including biologic) characteristics of cells in cases where the y cannot be determined by LM. With the accumulation of data on electro n microscopic examination of cytologic samples, it is expected that in the future, electron microscopy will continue to provide new informat ion that can be used to improve the accuracy of cytodiagnosis by LM.