Hair loss is very difficult to diagnose and treat. There are two main types of hair loss: Scarring(Cicatricial) and Non-Scarring. The categories can be delineated in a clinical exam.
Scarring Hair Loss
A scarring hair loss results in the loss of the hair follicles and clinically the ostia (the openings the hairs come out of the scalp) are obliterated resulting in a smooth shiny appearance.
Non-Scarring Hair Loss
The scalp appears completely normal in a non-scarring hair loss, except the density of the hairs is lower.
Do I Need a Skin Biopsy for Hair Loss?
In many cases, a biopsy is needed to determine the subtype of hair loss in the scarring and non-scarring categories. A punch biopsy is preferred and is easily done at the clinic visit. I clip a very small amount of hair (5mm) to clear an area for the biopsy and I typically use a 4mm punch biopsy which allows all three layers of the skin to be evaluated by the dermatopathologist. The subcutaneous layer of skin contains the hair follicle and this is where most of the important pathology exists. I limit the amount of bleeding with a scalp biopsy by using 3cc of lidocaine which tumesces the biopsy site. Tumescence produces a localized swelling so the capillaries are compressed and bleeding is minimal. 2 small sutures are placed to close the punch biopsy site and these are removed in two weeks. Unfortunately, the dermatopathology findings in hair loss are very subtle and the biopsy may be unrevealing in many cases. It is very important to use board-certified dermatopathologists to review all skin biopsies as they have specialized training in evaluating these subtleties. My patients can wash their hair with shampoo the same day of the biopsy and no special care is needed except applying Neosporin daily to the sutures. I remove the sutures two weeks after the biopsy and discuss the pathology results and treatment plan at the suture removal visit.
