Where should a scalp biopsy be taken from?

Choosing (Wisely) A Site to Biopsy

Scalp biopsies are a brief 10-15 minute procedure that allows the clinician to obtain a sample for analysis under the microscope.

Great care is needed to choose the spot or location to sample. Random biopsies are rarely helpful. The site should ideally be the site where the most changes representative of the potential disease in question are seen by the clinician or the most symptoms are felt by the patient (ie itching, burning and pain).

Far too often I evaluate biopsies form patients whereby a biopsy was taken from an area that is not truly representative of the disease that is believed to be present. Biopsies are often taken from an area that will be 'hidden' in the event that a scar forms. However, a biopsy should always be taken form a representative area or one should not take the biopsy at all. Too many biopsies for androgenetic alopecia are taken from the lateral (side) parts of the scalp rather than the central regions. This often yields information that is not always helpful. If a decision is made to take a biopsy, it must be taken from an area that is most likely to capture the disease in question. Otherwise my personal opinion is not to do it. 

Once the site is chosen, the area is marked with a dot (as shown in the photo). The scalp in this area is anesthetized ("frozen") with local anesthetic medications such as lidocaine. Then, a punch biopsy instrument is used to obtain a sample about 4 mm in diameter. The area where the sample was removed is then stitched with suture. The punch biopsy specimen is then sent to a dermatopathology lab for processing.  Results may take 2-6 weeks depending on the type of processing needed.