A comprehensive approach to hair pathology of horizontal sections.

Histopathologic interpretation of horizontal scalp sections is difficult because of the anatomical complexity of the normal pilosebaceous structures in different stages of the hair cycle. The objective of this work was to create a simplified approach that facilitates the diagnosis of horizontal sections. Nine easy to memorize images (photomnemonics) that resemble diagnostic patterns and features in horizontal scalp biopsies were identified after a year of evaluation of horizontal sections. To verify the matched combinations, 2 dermatopathologists and 15 dermatology residents were asked to complete a validation test. After a short PowerPoint introduction, they had to link 9 projected histopathologic slides to the corresponding photomnemonics from the answer sheet. The validation test showed that out of the 153 answered questions, 140 (92%) were correct, which confirms the relevance of the suggested associations: (1) nonscarring alopecias present with a "floral" pattern. The hair follicles and preserved follicular units can be assimilated to different flowers and plants. (2) In scarring alopecias, the most common pattern is the "eyes and goggles" on background of follicular dropout and fibrosis. The photomnemonics method does not substitute the conventional learning of the hair anatomy. It is rather an adjuvant tool that helps dermatopathologists to increase their interest and skills in hair pathology.