Rosacea under the microscope: characteristic histological findings

Rosacea is a common facial dermatosis that is seldom biopsied; thus, histological aspects have not been well described. Biopsies are generally performed in the presence of atypical symptoms (e.g. granulomas). Differential diagnosis with sarcoidosis, lupus miliaris or lupus erythematosus is another indication for biopsy. There are few published studies addressing the microscopic aspects of rosacea and describing the histological and immunohistochemical features of this disease. While some textbooks consider the microscopic signs of rosacea to be non-diagnostic, experienced dermatopathologists are generally able to make the diagnosis via histology. This article discusses the specific combinations of histological features that are highly suggestive of rosacea.