Primary Scalp Alopecia: New Histopathological Tools, New Concepts, and a Practical Guide to Diagnosis

The 2016 document provides a detailed examination of primary scalp alopecia, offering new histopathological tools and a revised approach to diagnosis. It challenges the traditional classification into scarring and non-scarring types, suggesting that all alopecias may lead to scarring. The authors introduce the HoVert technique for biopsy analysis, which allows for both horizontal and vertical sections, and the use of specific immunostains (CD3, CD123, and treponema) for certain alopecia types. They propose a 2-step diagnostic algorithm that relies on clinical clues and histopathological examination, emphasizing the importance of clinical context, such as hair pull test results, hair density, follicular size, and inflammatory infiltrate. The document describes the histopathological features of various alopecias, including acute and chronic telogen effluvium, anagen effluvium, alopecia areata, frontal fibrosing alopecia, and others, highlighting the need for accurate histopathological examination in diagnosis. The review aims to improve the accuracy of alopecia diagnosis by integrating new methods and a practical diagnostic guide.