[Diagnostic problems in skin tumors]

Several starting-points for improvement of diagnostic accuracy in skin tumors are illustrated by examples: Frequencies and direction of diagnostic errors, as well as the value of diagnostic criteria need further investigations. Frequent "customary" diseases need more attention in medical textbooks, compared with less frequent "interesting" syndromes. Erroneous denominations and historical false classifications which are handed down in the literature demand correction. The possibility continues, that apparently clearly defined entities may decay; they may be replaced by new entities in consequence of new perceptions.