Lichen planus (a chronic, immune-mediated inflammatory condition affecting the skin, scalp, nails, and mucous membranes) affects roughly 0.2 to 1 percent of the population. It is also one of the more frequently misdiagnosed inflammatory skin diseases. The reason is straightforward. Lichen planus looks different depending on where it appears on the body, and a presentation in the mouth bears almost no resemblance to one on the wrist.
At MedDerm in Hillcrest, San Diego, our board-certified dermatologists diagnose lichen planus through clinical examination and, where needed, biopsy. We then build a management plan around the specific pattern of disease, whether skin, scalp, oral, nail, or some combination of these. Lichen planus care sits within our broader medical dermatology practice.
Dermatologists summarize the classic skin presentation of lichen planus with five features known as the “5 P’s”:
These lesions appear most often on the wrists, forearms, ankles, and lower back. They can, however, develop anywhere on the body.
How lichen planus heals is itself a diagnostic clue. Affected skin often leaves behind a blue-black or brownish discoloration called post-inflammatory hyperpigmentation (darkening that persists after the original inflammation has cleared). This discoloration can take months to fade even once the active rash has resolved, and it is treated separately from the underlying disease. Patients troubled by lasting discoloration can ask about hyperpigmentation treatment alongside their lichen planus care.
In short: on the skin, lichen planus presents as itchy, flat-topped, violet, angular bumps that commonly leave lasting discoloration behind.
Inside the mouth, lichen planus looks nothing like the skin form. That difference is a major reason non-specialists miss the diagnosis.
The most common oral presentation is the reticular form (a lacy, white, web-like pattern on the inside of the cheeks, gums, tongue, or palate). The specific lacy white lines are known as Wickham’s striae, and they help confirm the diagnosis on examination. The reticular form is typically bilateral (present on both sides of the mouth) and causes little or no discomfort.
A more serious variant is erosive lichen planus (a form in which the surface tissue breaks down into raw, ulcerated areas). This variant causes genuine pain, particularly with spicy, acidic, or hot foods. It can affect the mouth, the genital skin, or both. Erosive disease resembles several other ulcerative conditions, including some autoimmune blistering diseases and, rarely, oral cancer. A biopsy is therefore usually required to confirm the diagnosis and rule out the alternatives.
In short: oral lichen planus most often appears as painless lacy white lines, but its erosive form is painful and requires biopsy to distinguish from more serious conditions.
Lichen planopilaris (lichen planus involving the hair follicles of the scalp) is the most time-sensitive presentation of this condition. It causes scarring alopecia (permanent hair loss caused by destruction of the hair follicle itself, rather than temporary shedding).
It usually begins with redness, scaling, and itching or burning around individual hair follicles, most often at the crown or along the part line. Unlike non-scarring hair loss, the damage cannot be undone. Once a follicle has been destroyed, hair will not regrow in that spot.
This is why timing matters so much here. How early lichen planopilaris is diagnosed and treated directly determines how much hair density can be preserved. Anyone noticing follicle-centered redness, scaling, or unexplained thinning should be evaluated promptly rather than waiting to see whether it resolves. Our approach to this and other forms of alopecia (hair loss) treatment begins with identifying whether the hair loss is scarring or non-scarring.
Frontal fibrosing alopecia (a scarring hair loss that recedes the frontal and temporal hairline in a band) is recognized as a clinical variant of lichen planopilaris. Under the microscope, the two are essentially indistinguishable, showing the same inflammation and concentric scarring around the hair follicle.
It differs in its pattern and in who develops it. Frontal fibrosing alopecia affects predominantly postmenopausal women, though premenopausal women and men can develop it as well. It commonly involves loss of the eyebrows alongside hairline recession, and the affected skin appears pale and shiny, with no visible follicular openings. A scalp biopsy is used to distinguish it from other causes of scarring hair loss.
In short, lichen planopilaris and frontal fibrosing alopecia both permanently destroy hair follicles, so treatment timing determines how much density is ultimately preserved.
Lichen planus can affect the nails. It causes thinning, longitudinal ridging, and in advanced cases a pterygium (permanent scarring in which the nail fold fuses to the nail bed and splits the nail plate). Because nail changes can also point to several other conditions, they are worth evaluating as part of a broader assessment of nail disorders.
Genital involvement ranges from mild, symptom-free changes to erosive lesions like those seen in the mouth. Genital and oral disease occurring together is known as vulvovaginal-gingival syndrome (a lichen planus pattern affecting the vulva, vagina, and gums simultaneously).
Erosive genital and oral disease resembles other conditions closely, including certain immunobullous disorders (blistering diseases). An accurate diagnosis from a board-certified dermatologist helps avoid both under-treatment and unnecessary alarm.
In short: nail and genital lichen planus carry a risk of permanent scarring, which makes early, accurate diagnosis the priority.
The exact cause of lichen planus is not fully understood. It is believed to result from a T-cell-mediated immune response (a reaction in which the body’s own immune cells mistakenly attack cells in the skin or mucous membranes) rather than from an infection. For this reason, lichen planus is not contagious.
Several associations are well established:
In short: lichen planus is an immune-mediated condition, not an infection, and while medications and hepatitis C are recognized associations, many cases have no identifiable trigger.
The classic 5 P presentation on the skin is often recognizable on sight. Oral, genital, nail, and scalp presentations are different. These frequently require a skin or mucosal biopsy (a small tissue sample examined under a microscope) to confirm the diagnosis.
Under the microscope, lichen planus has a distinctive appearance. A pathologist looks for a band-like collection of immune cells at the junction between the epidermis (the outer layer of skin) and the dermis (the supporting layer beneath it). Characteristic changes in the shape of the tissue architecture appear alongside it. Together these features separate lichen planus from conditions that can look similar on the surface, including lichen sclerosus, certain blistering diseases, lichenoid graft-versus-host disease, and cutaneous lupus erythematosus.
These two conditions are confused often enough to be worth setting side by side:
| Lichen planus | Lichen sclerosus | |
|---|---|---|
| Appearance | Itchy, purple, flat-topped bumps | Thin, white, sometimes crinkled patches |
| Typical sites | Wrists, ankles, mouth, scalp, nails, genitals | Primarily genital skin |
| Symptoms | Itch and pain where erosive | Itch, soreness, tightness, and scarring |
| Distinguishing test | Biopsy showing a band of immune cells at the epidermal junction | Biopsy showing thinned epidermis with dermal scarring |
One diagnostic point carries particular clinical weight. Longstanding erosive oral lichen planus is classified by the World Health Organization as an oral potentially malignant disorder. Pooled analyses of thousands of patients put the rate of transformation to oral squamous cell carcinoma at roughly 1.1 to 1.4 percent.
That figure is small, and it is worth stating plainly what it does and does not mean. Classic lichen planus on the skin carries no such increased risk. For longstanding erosive oral disease, the risk is real enough to warrant ongoing monitoring rather than a one-time diagnosis. That monitoring sits alongside routine skin cancer screening and treatment.
A biopsy is a brief in-office procedure, but one preparation step matters. Stop taking aspirin and ibuprofen one week before the procedure, as both increase bleeding, unless your prescribing physician has directed you otherwise. Bring a current list of all medications and supplements to the appointment. Our treatment rooms are kept deliberately cool, which most patients find adds to their comfort during the procedure.
In short: biopsy confirms lichen planus and rules out conditions that mimic it, and longstanding erosive oral disease warrants ongoing monitoring.
Lichen planus rewards diagnostic precision, which is why it matters who is reading the biopsy and the clinical picture together.
MedDerm is led by Michelle Terez Pelle, M.D., FAAD, a board-certified dermatologist, Clinician Educator, and contributing author to Fitzpatrick’s Dermatology, the field’s standard academic reference text. That academic grounding shapes how inflammatory skin disease is evaluated here, particularly for presentations like erosive oral and scalp disease where the diagnosis carries lasting consequences. You can review the full credentials of our dermatology practitioners before scheduling.
There is no cure for lichen planus. The disease can be actively managed, however, and many patients enter a dormant phase after treatment, particularly with skin-limited disease. Treatment is tailored to where the disease appears and how severe it is.
Two presentations call for prompt, active management rather than a watch-and-wait approach. Lichen planopilaris is one, because scarring hair loss is irreversible. Erosive oral and genital disease is the other, because of tissue scarring and the monitoring requirement described above.
In short: lichen planus cannot be cured, but it can be managed and often cleared for extended periods, with treatment matched to the site and severity of disease.
No. Lichen planus is an immune-mediated inflammatory condition, not an infection. It cannot be spread from person to person through touch or close contact.
The exact cause is not fully understood. It is believed to result from the immune system mistakenly attacking cells in the skin or mucous membranes. Certain medications, dental materials, and hepatitis C infection are recognized associations, though many cases have no identifiable trigger.
There is no cure. Lichen planus can be actively managed with topical, oral, or light-based treatment, and the disease often becomes dormant after a course of therapy.
Lichen planus typically causes itchy, purple, flat-topped bumps and can affect the mouth, scalp, and nails. Lichen sclerosus more often causes thinning, white patches primarily on genital skin. The comparison table above sets out the differences, and a biopsy distinguishes the two when the presentation is unclear.
In most cases, no. Classic lichen planus on the skin carries no increased risk. Longstanding erosive oral lichen planus is different. It is a recognized oral potentially malignant disorder, with a transformation rate to oral squamous cell carcinoma of roughly 1 percent. Ongoing monitoring is recommended for that specific presentation.
Yes, in one specific form. Lichen planopilaris affects the scalp and causes scarring alopecia, meaning hair follicles are permanently destroyed. Because that damage cannot be reversed, early evaluation and treatment are important for preserving hair density.
Classic skin lichen planus is often diagnosed on clinical examination. Oral, genital, nail, and scalp presentations usually require a skin or mucosal biopsy. The biopsy shows a distinctive band of immune cells and rules out conditions that look similar on the surface.
Lichen planus appears in several different forms: on the skin, in the mouth, on the scalp, and on the nails. Each presentation calls for its own diagnostic and treatment approach. The board-certified dermatologists at MedDerm in Hillcrest, San Diego evaluate the full picture, confirm the diagnosis with biopsy where needed, and build a management plan suited to your specific case.
