A study of etretinate alopecia

Twenty-two patients receiving etretinate were studied in an attempt to clarify the changes in hair cycle dynamics responsible for etretinate alopecia. Shed hair counts and telogen counts on samples of plucked hair were performed prior to therapy and after 6 and 12 weeks' treatment with etretinate. No evidence of anagen effluvium was found. In two individuals there were findings compatible with a classical telogen effluvium, but these had atypical features. The main finding in the study was an increase in the plucked telogen count, maximal at 12 weeks. As an arrest in the onset of anagen could produce only a comparatively small telogen increase, the predominant cause of this increase was a decrease in the duration of anagen. In two subjects there was also evidence of a telogen anchorage defect.