The Scalp Biopsy: Is it the "final" answer or just a piece of the puzzle?

Scalp biopsies are a piece of the puzzle.

Ahh the benefits of a scalp biopsy.  A favourite topic of mine.  A scalp biopsy refers to a short 10 minute procedures where a piece of skin and accompanying hair is taken from the scalp and sent off for analysis under the microscope.  The area where the skin was removed is then stitched up with sutures.

Scalp biopsies are a big help - Sometimes!

The scalp biopsy is a BIG help when performed in the right patient and at the right time in their hair loss progression. However, the scalp biopsy is unhelpful and potentially even detrimental to reaching the proper diagnosis when they are performed "just because". As an example let's look at these two scalp photos. The patient on the left AND the patient on the right both brought in results from their scalp biopsies showing inflammation and scarring. These two features are often seen in a group of autoimmune conditions called the "scarring alopecias" . Scarring in the biopsy from the patient on the left was reported as subtle but the final report indicated possible scarring alopecia (scarring hair loss condition). The patient in the right had scarring and inflammation in the biopsy and the pathology report indicated scarring alopecia. However after closely listening to the story of hair loss from the patient on the left and examining the scalp, patient 1 leaves the office with a diagnosis of seborrehic dermatitis (a type of dandruff) and genetic hair loss and NOT a diagnosis of scarring alopecia. Powerful immune system suppressing drugs were NOT started but rather proper treatments for genetic hair loss and seborrheic dermatitis. After listening to the patient's history and examining the scalp, patient 2 (on the right) leaves the office with a diagnosis of scarring alopecia (lichen planopilaris). Powerful immune system suppressing drugs were started. 

Final Point: Never Rely on a Biopsy alone!

The final point is that a scalp biopsy is not the "final answer" to why a patient is losing hair. Information from the biopsy needs to be pieced together with:  1) the patient's history of hair loss and 2) what the scalp looks like "up close" and also 3) what the blood test results show.  If I'm planning to do a biopsy on my patient these other three things need to be carefully taken into consideration.