Stereology and morphometry in histopathology. Principles of application

The role of stereology and morphometry (including image analysis) in histopathology is considered. Diagnostic histopathology has its own character, which should be considered when quantitative methods are applied. Three different types of studies in histopathology can be distinguished: prospective, retrospective and routine diagnostic studies. The variation in these studies is due to differences in the methods and differences in how the methods are applied. The overall variation is smallest in prospective studies and largest in routine diagnostic studies. Statistical classification of the overall variation does not cover all relevant aspects of the situation in which we study the sample from one individual patient. In that situation, we do not get support from the samples of other patients. In fact, we should speak about group morphometry (statistical morphometry) when samples from several patients are studied and diagnostic morphometry when the sample from one individual patient is under investigation. In the former case, simple morphometric methods may be applicable (the researcher is interested in mean values). In the latter case, one would often like to analyze the sample in more detail. This is why the diagnostic situation may benefit from computerized image analysis, which allows collection of large amounts of data in a short time. On the other hand, the great variation between the pathologic and the normal can allow the use of simple methods. The above basic principles need be considered before morphometric and stereologic methods are applied. These methods are simple in practice and they should be included in the training of all pathologists.