**2. Causes of alopecia**

Alopecia can be either scarring or non-scarring. Non-scarring alopecias tend to have preserved follicular ostia, with no clinically visible inflammation in most presentations, although histologic inflammation may be present. The common types of non-scarring alopecias are androgenic alopecia, telogen effluvium, alopecia areata, trichotillomania and traction alopecia. Scarring alopecias, also known as cicatricial alopecia, refers to a collec‐ tion of hair loss disorders that have loss of follicular ostia, or atrophy, with permanent and irreversible destruction of hair follicles and their replacement with scar tissue. The histologic confirmation is the best method to confirm the presence of a fibrosing/scarring process with loss of hair follicles.

Scarring alopecias can be classified as lymphocytic (discoid lupus erythematosus (DLE), lichen planopilaris (LPP), central centrifugal cicatricial alopecia, pseudopelade of Brocq), neutro‐ philic (folliculitis decalvans, dissecting folliculitis), and mixed (acne keloidalis) entities [1].

Many alopecia types are biphasic. For example, androgenetic alopecia eventually results in loss of ostia and thus may appear like a scarring alopecia.

© 2013 Al-refu; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

To establish the cause of the hair loss, one requires a history to identify known triggers, scalp examination, biochemical investigations and in many cases histology to identify the earliest stages of some types of alopecias esp scarring alopecia.

**4. Technique of scalp biopsy**

**5. Vertical sections**

vertical sections.

**Figure 2.** Vertical section of a scalp biopsy from a patient with DLE.

It is a crucial to determine the appropriate site of a scalp biopsy to have a correct diagnosis of alopecia,andthisapproachisdifferentinscarringandnon-scarringtypes.Forascarringprocess, the biopsy should be taken from the active border of hair loss where some hairs still remain and are more likely to display diagnostic findings. For non-scarring alopecias, the preferred site of biopsy is generally the border of a lesion (positive exclamation marks in alopecia areata), or from thesiteofapositivepulltestinthesettingofadiffusealopecia.Inthesettingofevaluatingapossible androgenic alopecia, two biopsies, one from the involved scalp (often vertex) and one from the

Scalp Biopsy and Diagnosis of Common Hair Loss Problems

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The current gold-standard for a scalp biopsy specimen is the use of a 4-mm punch and must include subcutaneous fat to ensure sampling of the entire follicular unit and any anagen follicles; the specimen may be sectioned vertically or transversely [2]. Although a combination of the two may be optimal, the pathologist is frequently only provided with a single specimen.

Vertically-sectioned punch biopsy specimen is adequate for assessing alopecias associated with interface changes, lichenoid infiltrates, and subcutaneous pathology [3]. However, vertical sectioning will show only 10% of the follicles present in the specimen [4]because the hair follicles, which grow at an angle, cannot be visualized in their entirety in conventional

uninvolved scalp (often occiput; serves as a positive control) may be beneficial.
