Lichen planus pigmentosus (LPP) is a chronic skin disorder characterized by the development of brown to dark gray patches on the body that typically appear after the age of 30 (Weston and Payette, 2015). Though present in all races, it appears to be most common in those with a deeper skin tone, primarily those of Indian descent (Kanwar et al., 2003; Mendiratta and Chander, 2019). Women appear to be more frequently affected (Bhat et al., 2017).
Though this condition is not associated with other symptoms, it can cause psychosocial stress to patients who have to deal with the changes in their physical appearance.
What does lichen planus pigmentosus look like?
LPP is an insidious disease that starts off with small, flat, brown, roughly oval patches (Ghosh and Coondoo, 2016), similar in appearance to its namesake, lichen. Just like lichen that steadily grows over the surface of trees and rocks, LPP lesions also spread, coalescing to cover larger regions. TThe pigmentation may become dark brown or purplish gray, and can be diffuse, blotchy, or focus around the hair follicles.
These are typically found in sun-exposed areas, primarily in the face, neck, arms, and trunk. It is also known to occur in areas that receive a high amount of friction, such as the armpits, groin, and under the breasts.
Under the microscope, the skin of LPP patients show epidermal atrophy, hyperkeratosis, inflammatory infiltrate in a band- or lichenoid pattern, and melanin incontinence at the level of the dermis (Ghosh and Coondoo, 2016). To the naked eye, these microscopic changes manifest as the flat, hyperpigmented patches found on LPP patients.
Unlike other variants of lichen planus, LPP does not cause any itchiness. The lesions are not preceded by redness, pain, swelling, or discomfort (Matthews et al., 2016).
It can be difficult to differentiate LPP from other hyperpigmentation disorders based on clinical examination of the skin alone (Ghosh and Coondoo, 2016). A thorough history taking and possibly histopathological analysis of a skin sample can help with diagnosis.
What causes lichen planus pigmentosus?
The short answer is--we don’t know for sure. LPP is not as well studied as other dermatological conditions. But being a variant of lichen planus, LPP is thought to be an autoimmune reaction to an as-yet-unidentified protein within skin cells (Bhat et al., 2017).
There are a number of factors associated with this condition. Ultraviolet radiation from the sun is hypothesized to trigger LPP, primarily because it appears in sun-exposed areas of the skin (Chen, 2022). However, this distribution is more common in darker-skinned patients. In lighter skinned patients, the lesions are found in intertriginous zones such as the armpits and groin (Matthews et al., 2016). This has been called “lichen planus pigmentosus-inversus” (Gaertner and Elstein, 2012).
Photosensitizing agents are another prime suspect in the line-up of LPP triggers. Mustard oil, Indian gooseberry or amla oil, kumkum powder used as ritual skin pigmentation in India, and hair dyes are some examples (Kanwar et al., 2003). However, in other studies,
There have been multiple reports of LPP occuring after patients had undergone gold therapy, a formerly popular treatment for rheumatoid arthritis (Hjortshoj, 1977; Ingber et al., 1986).
LPP has also been associated with certain disease conditions including hepatitis C (Vachiramon et al., 2010) and hypothyroidism (Mendiratta, 2019).
What can I do about lichen planus pigmentosus lesions?
LPP has been known to spontaneously regress, but for the majority of cases, the marks persist and often continue to grow throughout life. While treatments are available, this condition is considered difficult to control, with results varying from person to person.
Jumping off from the understanding that LPP is an immune disorder, the most commonly-used treatments are immunomodulators such as tacrolimus cream and steroids (Khan et al., 2022). Other options include retinoids, oral dapsone, and medical procedures like laser therapy and chemical peels.
This content is for general information only and is not a substitute for medical advice.
References:
Bhat, R. M., Mathanda, T. R., Jayaprakash, C. S., & Dandakeri, S. (2017). Clinical, Histopathological Characteristics and Immunohistochemical Findings in Lichen Planus Pigmentosus. Indian journal of dermatology, 62(6), 612–617. https://doi.org/10.4103/ijd.IJD_148_17
Chen, M. (2022). Lichen planus. Accessed 29 December 2022. https://dermnetnz.org/topics/lichen-planus
Gaertner, E., & Elstein, W. (2012). Lichen planus pigmentosus-inversus: Case report and review of an unusual entity. Dermatology Online Journal, 18(2). http://dx.doi.org/10.5070/D356c7h5nt Retrieved from https://escholarship.org/uc/item/56c7h5nt
Ghosh, A., & Coondoo, A. (2016). Lichen Planus Pigmentosus: The Controversial Consensus. Indian journal of dermatology, 61(5), 482–486. https://doi.org/10.4103/0019-5154.190108
Hjortshoj A. (1977). Lichen planus and acne provoked by gold. Acta dermato-venereologica, 57(2), 165–167.
Ingber, A., Weissmann-Katzenelson, V., David, M., Bialowons, M., & Feuerman, E. J. (1986). Lichen planus und Lichen planus pigmentosus nach Goldtherapie--Fallberichte und Literaturübersicht [Lichen planus and lichen planus pigmentosus following gold therapy--case reports and review of the literature]. Zeitschrift fur Hautkrankheiten, 61(5), 315–319.
Kanwar AJ, Dogra S, Handa S, Parsad D, Radotra BD. A study of 124 Indian patients with lichen planus pigmentosus. Clin Exp Dermatol. 2003;28:481–5.
Khan W., Fatima, S., Javed, M. (2022). BC04: Treatment and outcomes for lichen planus pigmentosus: a literature review British Journal of Dermatology, Volume 187, Issue S1, 1 July 2022, Page 85, https://doi.org/10.1111/bjd.21309
Mathews I, Thappa DM, Singh N, Gochhait D. Lichen planus pigmentosus: A short review. Pigment Int 2016;3:5-10
Mendiratta, V., Sanke, S., & Chander, R. (2019). Lichen Planus Pigmentosus: A Clinico-etiological Study. Indian dermatology online journal, 10(3), 288–292. https://doi.org/10.4103/idoj.IDOJ_253_18
Vachiramon, V., Suchonwanit, P., & Thadanipon, K. (2010). Bilateral Linear Lichen Planus Pigmentosus Associated with Hepatitis C Virus Infection. Case reports in dermatology, 2(3), 169–172. https://doi.org/10.1159/000320775
Weston, G., & Payette, M. (2015). Update on lichen planus and its clinical variants. International journal of women's dermatology, 1(3), 140–149. https://doi.org/10.1016/j.ijwd.2015.04.001
