PracticalDermatology

Historically characterized by the “Ps,” Lichen Planus, which can effect skin, nails, and mucous membranes, manifests differently in different skin types.

With fairer skin, for example, papules and plaques are faint purple and can have overlying, interlaced scale. In darker skin types, papules and plaques can appear more purple, or even brown/black without obvious scale (though if one looks closely, one can sometimes see faint white lines indicative of Wickham striae).

SkinBetter Science and Allergan Aesthetics, an AbbVie company, have launched the new DREAM: Driving Racial Equity in Aesthetic Medicine (DREAM) Initiative, which is sponsoring the development of “The Full Spectrum of Dermatologic Disease: A Diverse and Inclusive Atlas,” a comprehensive textbook photo atlas that will present the characteristics of skin conditions across the full range of skin types. The text will be disseminated to residents, faculty, and program libraries and will be available as a resource for clinical practitioners worldwide.

Here, textbook co-editors Adam Friedman, MD, Professor and Interim Chair of Dermatology at George Washington University in Washington, DC, and Misty Eleryan, MD, a Micrographic Surgery and Dermatologic Oncology Fellow at UCLA David Geffen School of Medicine/West LA VA Medical Center in Los Angeles, shed some light on how Lichen Planus presents in various skin types and what to look out for when developing a differential diagnosis.

A More Classic Presentation

The more historical description of Lichen Planus—we all may remember the P’s of lichen planus from our medical school days—is appreciated in these images of fairer skin where flat-topped polygonal pink to light purple papules with hemi-arcuate or annular scale is noted on the dorsal foot (Figure 1a) and a linear (suggesting an outside job or in this case, koebnerization) to hemi-arcuate pink to light purple plaque comprising of coalescing flat-topped papules or guttate plaques with geometric, intercalating scale (representative of Wickham striae) on the dorsal hand. (Figure 1b) No scarring or dyspigmentation is noted.

Postinflammatory Changes

Ovoid hemiannular and annular plaques, some with prominent white scale, with two unique color patterns, first, violaceous with peripheral hyperpigmentation and second, white-pink centrally with peripheral hyperpigmentation. Note the impressive postinflammatory changes resulting from pigment incontinence due to the lichenoid inflammation associated with this condition. (Figure 2a) Whereas in fairer skin, papules and plaques are more a faint purple, here the color is darker and, with the post-inflammatory changes, could clinically mirror discoid lupus. Often the dyspigmentation is more disfiguring then the disease itself, often difficult to resolve even with the treatment modalities available and especially when involving a sun exposed area. Similarly that darker purple is noted, in this example of more papular or guttate lichen planus (Figure 2b), which, given the appearance, could be confused for guttate psoriasis. The planar flat topped morphology and peripherally focused collerette appearance of scale is distinguishing.

Rethink Lesion Color

The most striking feature is the banal appearance of these grouped, flat-topped brown-to-black papules, but don’t be fooled! These are active inflammatory papules. (Figure 3a) Often in dark skin types, erythema itself can appear dark purple, as mentioned above, but even more misleading with lichenoid inflammatory processes, it can appear purple-to-black. Notice how the light catches a faint white-pink pattern on the surface, which could be elucidated by shining the light of your dermatoscope, helping to appreciate the active inflammatory nature of these papules. (Figure 3b) Location on the volar surface of the forearm is certainly a helpful clue to considering lichen planus in the same patient. Once again, that faint off white/pink overlying the dark purple/black like a veil should alert you to an active lichenoid infiltrate.

Expect the Unexpected

Expect the unexpected and look for the clues. In this image of lichen planus koebnerizing in a tattoo, notice the collerettes of scale and dark purple to brown/black appearance. (Figure 4a) The papules and plaques are flat topped and only in areas of tattoo injection. (Figure 4b) Don’t have tunnel vision as you look at these black, hyperkeratotic plaques and crusted nodules that could be confused for a neurodermatitis at first glance. Enjoy the extensive interconnecting of Wickham striae in the semi-linear plaque and the tiny violaceous papules with trailing colerettes of scale on the dorsal foot.