[Diagnostic validity and variability of histopathology].

Histopathology plays an important role in practical medicine, especially in making the definite diagnosis and proper choice of treatment. However, since its methodology relies upon inspective and rather intuitive recognition of morphologic patterns, the pathologist may commit interpretive errors accidentally. Consequently, a quality-control (QC) mechanism should be developed at the pathologic laboratory to arrive at a higher level of diagnostic accuracy beyond the individual pathologist's capacity. The aims of QC are: (1) to disclose erroneous diagnoses and their responsible causes, so that remedial and preventive measures can be effectively devised for patient not to be maltreated, and (2) to verify the practical accuracy of diagnoses and cultivate the pathologist's self-confidence. Indeed, QC aims at the perfect diagnostic agreement among pathologists, but, in reality, there is considerable interobserver variability for some diseases. It seems to be a negative factor to lower the level of diagnostic validity. However, the variability is a pathologist's challenge from a variety of view-points to fully understand the disease of currently unknown pathology or without generally accepted diagnostic criteria.