Lichen Planopilaris: What's important on Biopsy - and What's just a Source of Confusion

What do I look for in scalp biopsy reports?

There is not a month that goes by that I don’t consult with a new patient who comes into the clinic worried he or she has lichen planopilaris and leaves the visit knowing they don’t. It’s a happy consultation to say the least.

The typical patient who fits this description is a patient with androgenetic alopecia who undergo a scalp biopsy because the clinician was worried about the possible diagnosis of a scarring alopecia. Many of these patients have androgenetic alopecia and either seborrheic dermatitis or psoriasis that gives some degree of redness, and scalp symptoms like itching or burning. Increased shedding is usually present.

And so a biopsy is done to exclude scarring alopecia like lichen planopilaris which also gives itching and burning and redness and shedding.

Makes perfect sense. Biopsy sounds okay to me.

The problem arises when a pathologist notes perifollicular fibrosis and perifollicular inflammation in the biopsy and attributes these findings incorrectly to a diagnosis of lichen planopilaris. Usually in these misdiagnosed cases there is no evidence of loss of sebaceous glands and lichenoid inflammation is not present. Not even a keratinocyte has died.

LPP and AGA have MANY shared features!

There are many features of lichen planopilaris and androgenetic alopecia that are the same. Both conditions have perifollicular fibrosis although the degree of fibrosis may sometimes be more in LPP (but not always). Both conditions have inflammation. Not surprising … it’s easy to get confused.

Lichen planopilaris is a destructive process and ideally I like to have AT LEAST ONE PIECE OF GOOD EVIDENCE pointing to destruction, namely: 

1) loss, reduction or at least atrophy of sebaceous glands or

2) death of hair follicle keratinocytes (lichenoid change or necrosis).

If I don’t have any of these two, I’d like the pathologist to help me figure out 3) if elastic tissue has been destroyed using some kind of elastin stain. 

If none of these three features are present and clinically the story does not fit with scarring alopecia, we either need to abandon the original diagnosis or rebiopsy again to try to prove this is a scarring alopecia!!!!

I encourage doctors  I work with to get in the habit of crossing out the words “perifollicular fibrosis” and “perifollicular inflammation “ in biopsy reports and seeing what information is left over. If the report seems strange or incomplete … one needs to call the pathologist for more information or rebiopsy!