Sebhorrheic Dermatitis in LPP: Is it more common than we think?

Is it more common than we think?

Current evidence would suggest that a greater proportion of patients with lichen planopilaris (LPP) have seborrheic dermatitis compared to people in the general population. For example, about 5% of people in the general population have seborrheic dermatitis compared to about 50% of patients with 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 as it was one of the few studies to date which really documented the increased incidence of seborrheic dermatitis in patients with LPP.

The study 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 diagnosis in 7.6 months on average compared 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%). On account of seborrheic dermatitis being so common in LPP, it makes sense that many people with LPP will feel better and gain at least some relief of their itching with use of antidandruff shampoos.

Reference

Ratnaparkhi et al. Association of lichen planopilaris with seborrheic dermatitis l: A retrospective case-control study. Poster 3727. JAAD May 2016.