Semiquantitative analysis of histologic criteria in thin malignant melanomas

To evaluate the sensitivity of histologic criteria 396 hematoxylin-eosin-stained step sections of 150 randomly sampled thin malignant melanomas (tumor thickness, less than or equal to 1.5 mm; level of invasion, I-III) were analyzed. The highest sensitivity was determined for nuclear atypia (84%), followed by the asymmetry of the lesion (81.3%) and the presence of single cells in the upper layers of the epidermis (80.3%). The sensitivity was limited for the inflammatory reaction of the dermis (56%), poor demarcation of the lesion (49.3%), and infiltration of the adnexa (47.7%). For the mitotic activity a low sensitivity was found (33.3%). In only 7.6% of cases all criteria investigated (with the exception of the infiltration of adnexa) were simultaneously present. The three most sensitive criteria could be found in 46% of cases and two of these criteria in 88% of cases. In conclusion, this semiquantitative analysis of histologic criteria revealed that (1) thin malignant melanomas can be diagnosed with a few, but very sensitive, criteria and (2) the absence of criteria with minor sensitivity is not helpful for correct diagnosis.