ABSTRACT
Scalp biopsy is a helpful technique in the management of hair and scalp disorders. It is crucial for the diagnosis of scarring alopecia and helpful for differentiating non-scarring alopecias based on follicular counts and ratios in horizontal section. Scalp biopsies are not useful in the diagnosis of hair shaft disorders for which trichoscopy and electron microscopy should be utilized to make the diagnosis. The histopathologic interpretation of follicular findings in scalp biopsies is difficult because of the anatomical complexity of normal follicular structures in different stages of the hair cycle. Horizontal sections are superior to vertical sections in the study of the diameter of the hair follicles and the hair cycle. There is no evidence that a panel of special stains or immunohistochemical stains can be useful for routine use in hair pathology. The infiltrate contains also giant cells, edema, dilated vessels, and red blood cell extravasation.
