An approach to clinical dermatologic diagnosis based on morphologic reaction patterns.

How do dermatologists examine a patient and instantly generate a differential diagnosis? Of course, as in any other field, experience plays a large role. After a condition with a distinctive appearance is seen hundreds of times, recognition becomes automatic. Nevertheless, dermatologists need to employ a disciplined mental process to generate a differential diagnosis from clinical findings. From the perspective of clinical diagnosis, all dermatology falls into 2 separate categories--inflammatory and neoplastic. The reaction pattern technique discussed in this article relates only to inflammatory conditions such as psoriasis, eczema, and urticaria. This article describes an approach to differential dermatologic diagnosis based on clinical reaction patterns.