Interface dermatitis. How specific are its histopathologic features?

O OF THE more challenging aspects of being a dermatopathologist is to try to make specific diagnoses of inflammatory skin diseases. While it is true that, at one time, the tools to do this were inadequate, criteria now exist for the microscopic diagnosis of many inflammatory skin diseases, and most expert dermatopathologists have a sense of how to handle discrepancies between clinical and histopathologic findings. These developments have, hopefully, changed the negative feelings of many clinical dermatologists regarding the utility of biopsy procedures in inflammatory conditions. Because of the work of Herman Pinkus,1who ordered inflammatory skin diseases by reaction patterns (eg, lichenoid, eczematous, and psoriasiform dermatitis), Wallace Clark, who outlined patterns of inflammatory cells in cutaneous infiltrates, and Bernard Ackerman, who developed Clark's outline into a method of diagnosis in hisHistologic Diagnosis of Inflammatory Skin Diseases,2present-day dermatopathologists can specifically diagnose many inflammatory skin diseases. Even