High-power field

A high-power field (HPF), when used in relation to microscopy, references the area visible under the maximum magnification power of the objective being used. Often, this represents a 400-fold magnification when referenced in scientific papers. A high-power field (HPF), when used in relation to microscopy, references the area visible under the maximum magnification power of the objective being used. Often, this represents a 400-fold magnification when referenced in scientific papers. The area provides a reference unit, for example in reference ranges for urine tests. Used for grading of soft tissue tumors: Grading, usually on a scale of I to III, is basedon the degree of differentiation, the average number ofmitoses per high-power field, cellularity, pleomorphism,and an estimate of the extent of necrosis (presumably areflection of rate of growth). Mitotic counts and necrosisare the most important predictors.