Lichen planopilaris (LPP) is a rare, inflammatory condition of the scalp that results in a type of permanent hair loss called scarring alopecia. LPP targets the hair follicles, leading to their destruction and replacement with scar tissue. As a consequence, the affected areas of the scalp can no longer grow hair, leading to permanent bald patches. Understanding this condition involves examining its underlying cause, recognizing its physical signs, and navigating the specialized methods used for diagnosis and management.
Defining Lichen Planopilaris
Lichen planopilaris is classified as a primary lymphocytic cicatricial alopecia, which means its root cause is inflammation primarily involving lymphocytes, and it leads to scarring. Experts consider LPP to be an autoimmune condition. In LPP, immune cells known as T-cells appear to target the hair follicles, specifically the area known as the bulge, which houses the hair follicle stem cells.
This misguided immune attack initiates a chronic inflammatory response concentrated around the hair follicle. The inflammation gradually damages and ultimately destroys the hair follicle’s ability to regenerate hair. As the follicle is destroyed, it is replaced by dense, fibrous scar tissue. This irreversible scarring prevents any future hair growth.
LPP is considered a follicular variant of lichen planus. While the exact trigger for this autoimmune response remains unknown, the mechanism involves the destruction of the hair follicle from the inside out. The goal of managing LPP is to suppress this chronic inflammation to halt the progressive destruction of additional hair follicles.
Recognizing the Signs and Symptoms
One of the most common complaints is persistent itching, medically termed pruritus, which can be accompanied by a burning sensation or outright pain. These symptoms are often indicators of active inflammation and disease progression.
Visually, LPP presents as patches of hair loss, frequently affecting the crown and vertex of the scalp. In active areas, the scalp often shows perifollicular erythema (redness surrounding the hair follicles). A characteristic sign is peripilar desquamation, which is fine, tubular scaling that clings to the hair shaft.
The patches of hair loss are typically irregular and can be multifocal, eventually merging into larger, bald areas. In the scarred areas, the skin may appear smooth and shiny, and the hair follicle openings will be absent.
Confirming the Diagnosis
The process begins with a detailed clinical examination, where a dermatologist assesses the scalp for characteristic signs like perifollicular erythema and scaling. This is typically followed by a specialized examination using a handheld device called a dermatoscope, a procedure known as trichoscopy.
Trichoscopy allows for a magnified view of the scalp structures, which can reveal specific patterns associated with LPP. Key trichoscopic findings in active LPP include perifollicular scaling and erythema. In later stages or scarred areas, the examination may show white-to-milky-red areas and a complete absence of follicular openings.
While clinical and trichoscopic findings are highly suggestive, the gold standard for confirming LPP is a scalp punch biopsy. This minor procedure involves taking a small tissue sample from an area showing active disease, usually at the edge of a hair loss patch. The sample is processed and examined by a pathologist, who looks for a dense inflammatory infiltrate of lymphocytes surrounding the hair follicle, confirming follicular destruction and scarring.
Current Treatment Approaches
The primary objective of LPP treatment is to immediately halt the inflammatory process and prevent further irreversible hair loss. Treatment is generally tailored to the extent of the disease, often starting with topical or intralesional therapies for localized disease and progressing to systemic options for more widespread or aggressive cases.
Topical Treatments
High-potency topical corticosteroids are a mainstay of initial treatment, working to suppress the localized inflammation causing the follicular damage. These are typically applied directly to the active areas of the scalp for a limited duration due to the risk of side effects like skin thinning. Topical calcineurin inhibitors, such as tacrolimus, provide an alternative anti-inflammatory action and are often used alongside or instead of corticosteroids.
Intralesional Injections
For active, clearly defined patches of LPP, intralesional corticosteroid injections are frequently used. This approach delivers a high concentration of the anti-inflammatory medication directly into the site of the active lesion. The localized effect helps to quickly suppress the inflammation while minimizing systemic exposure to the drug.
Systemic Therapies
For more extensive, rapidly progressing, or symptomatic LPP, oral systemic medications are required to manage the widespread autoimmune activity. The anti-malarial drug hydroxychloroquine is often considered a first-line systemic option. Patients taking this medication require regular eye examinations to monitor for potential retinal side effects.
Other systemic options include immunosuppressants like methotrexate, cyclosporine, or mycophenolate mofetil. These medications work by broadly modulating the immune system. Due to the potential for more significant side effects, these treatments necessitate careful monitoring and are usually used for long-term control of the disease.