The Role of the Scalp Biopsy in the Evaluation of Alopecia

A scalp biopsy is crucial in accurately diagnosing alopecia, according to the document. The standard procedure involves a 4-mm punch biopsy extending into the fat, sectioned horizontally at multiple levels. The biopsy site selection, which depends on the type of alopecia, can significantly influence the diagnosis. The document also emphasizes the importance of the clinician's information provided to the pathologist, including the precise biopsy site and a clinical differential diagnosis. The wording in the biopsy report can indicate the level of diagnostic certainty, with phrases like “changes diagnostic of…” or “typical of…” indicating high certainty, while “consistent with” or “compatible with” suggest probable validity, and “suggestive of…” indicating low certainty. The document also notes that if the initial biopsy site selection is incorrect, an additional biopsy may be needed.