Special Stains and Immunohistochemical Stains in Hair Pathology.

BACKGROUND: Patterns in scalp biopsies can overlap, and distinction may be difficult. OBJECTIVE: To review the current knowledge about the usefulness of special stains and immunohistochemical stains (IHC) for the diagnosis of hair disorders. METHODS: The authors used the search engines PubMED, MEDLINE, and MeSH to retrieve articles on the application of special stains and IHC in hair pathology. RESULTS: The authors selected 65 relevant articles discussing the use of special stains and IHC markers in scalp biopsies, including case reports and original articles. No reviews on the subject were found. Although fungal stains, such as periodic acid-Schiff, are very helpful in the diagnosis of noninflammatory tinea capitis, they may be negative in kerion. Elastic stains may help to diagnose end-stage scarring alopecia on vertical sections. Stains for mucin may help to distinguish lupus erythematosus from lichen planopilaris. Lymphocytic markers may assist in the diagnosis of lymphoma-associated alopecia. CONCLUSIONS: On a practical level, there is no evidence to recommend the routine use of a stain or a panel of stains in hair pathology. No stain can distinguish between nonscarring and early scarring alopecia. Most IHC stains are currently limited to the experimental and research setting.