Seborrheic Dermatitis vs Lichen Planopilaris: Which do I have?
QUESTION
QUESTION:
My doctors can’t decide if I have seborrheic dermatitis or lichen planopilaris. My scalp does feel less itchy and becomes less red with anti dandruff shampoos. However, it also becomes less red and itchy with topical steroids. Overall my shedding has improved after 4 weeks of treatment. Does this information suggest one diagnosis over the other?
ANSWER:
Thanks for the great question. The short answer is that the information provided here does not actually suggest one diagnosis over another. You may have scarring alopecia and you may have seborrheic dermatitis. The key point I would like to make is that you may have both! Up to 50 % of patients with lichen planopilaris have seborrheic dermatitis too. A scalp biopsy can fully answer your question.
Let’s take a closer look at both of these conditions and we’ll see why some patients with lichen planopilaris will benefit from anti-dandruff shampoos and we’ll see why some patients with seborrheic dermatitis benefit from topical steroids (the same ones used to treat lichen planopilaris.)
SEBORRHEIC DERMATITIS
First, seborrheic dermatitis is closely related to dandruff. The exact cause is still being worked out but yeast such as Malassezia may have an important role. Patients with seborrheic dermatitis have many similar (and sometimes identical) symptoms to patients with lichen planopilaris. They have a red, itchy scalp! Seborrheic dermatitis however does not cause scarring for most people and usually only gives minor amounts of hair shedding. (Everything in medicine has exception and seborrheic dermatitis may cause scarring in some cases and may give excessive hair shedding when severe - see previous articles below).
DOES SEBORRHEIC DERMATITIS CAUSE SCARRING?
CAN SEBORRHEIC DERMATITIS TRIGGER SHEDDING?
Seborrheic dermatitis is an inflammatory condition which means there is inflammation in the scalp. Although the standard first line treatment for seborrheic dermatitis is topical anti-dandruff shampoos, treatment with anti-inflammatory agents like topical steroids can help reduce the inflammation which in turn reduces redness and itching. Many patients with seborrheic dermatitis feels better with use of both antidandruff shampoos and topical steroids. In fact, studies have shown that adding topical steroids to a patient’s seborrheic dermatitis treatment plan can greatly help.
To come back to your question for a moment, we would expect seborrheic dermatitis to improve with dandruff shampoos and topical steroids. However, fact that your scalp did improve does not rule out a scarring alopecia as we’ll see next.
LICHEN PLANOPILARIS
Lichen planopilaris is a scarring alopecia that causes patients to experience itching and sometimes burning and tenderness in the scalp. The scalp is typically red. An important difference between lichen planopilaris and seborrheic dermatitis is that lichen planopilaris always associated with scarring. Biopsies of LPP show rings of scar tissue around hair follicles in early stages (called concentric perifollicular fibrosis) and deposits of large bits of scar tissue in the scalp in advanced stages.
Topical steroids are one of many agents used to treat LPP. They help reduce redness and scaling and help the patient feel better too with less itching, burning or pain.
Seborrheic Dermatitis in Patients with LPP: Is is More Common than We Realize?
Seborrheic dermatitis is present in a very large proportion of patients with LPP. In fact, a greater proportion of patients with LPP have seborrheic dermatitis compared to people in the general population. (About 5% of people in the general population have seborrheic dermatitis compared to nearly 50% of patients with LPP). On account of seborrheic dermatitis being so common in LPP, it makes sense that many people with LPP will feel better and gain some relief with use of antidandruff shampoos! The fact that a patient with LPP reports improvement with antidandruff shampoos does not rule out a scarring alopecia. It simply means they may have seborrheic dermatitis too!
Cleveland Clinic 2016 Study of Seborrheic Dermatitis in LPP
In 2016, Berfeld’s group at the Cleveland clinic studied the incidence of seborrheic dermatitis in patients with lichen planopilaris. This study is important to understand and relevant to the above discussion. It was one of the few studies to date which really documented the increased incidence of seborrheic dermatitis in patients with LPP.
The study I am referring to was a retrospective review of 246 patients seen over the period 2004-2015. Interestingly seborrheic dermatitis (SD) was present in 46.2 % of LPP cases. In 27.4 % of cases the SD was found outside the area affected by the LPP. On average the SD was diagnosed 7.8 months prior to the LPP diagnosis. Having SD seemed to delay an actual diagnosis of LPP. Patients with both SD and LPP diagnosis (LPP-SD) received their diagnosis with significantly more delay than patients with LPP who did not have SD (ie LPP). For example, patients with LPP-SD received their diagnose in 7.6 months on average comapred to 2.3 months for LPP alone.
Whether SD actually plays a role in the scarring process as well remains to be determined. It is interesting that there was a greater prevalence of late stage scarring alopecia in ptient with LPP-SD than LPP alone (41.5 % vs 15.7%). Patients with LPP-SD had greater rates of hyperandrogenism compared to patients with LPP alone.
SUMMARY AND CONCLUSION
Thanks again for the great question. One can’t determine if you are more likely to have SD or LPP from the information provided. It would be entirely within the realm of expected for a patient with LPP to improve with topical antidandruff agents since many have seborrheic dermatitis present as well. Likewise, it would be expected that a patient with seborrheic dermatitis would improve with topical steroids because this is an inflammatory disease just like LPP.
A biopsy can help distinguish if lichen planopilaris is truly present or not.
Reference
Ratnaparkhi et al. Association of lichen planopilaris with seborrheic dermatitis l: A retrospective case-control study. Poster 3727. JAAD May 2016.
https://www.aad.org/eposters/view/Meeting.aspx?id=43&c=2