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SUMMARY
Lichen plano-pilaris (LPP) is a lymphocitic cicatricial alopecia considered the most common cause of scarring hair loss in adults.
It’s characterized by different pattern of hair loss on the scalp, ranging from a localized to a diffuse disease.
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TIPS FOR DIAGNOSIS
The clinical and trichoscopical evaluation should include the whole scalp, as well as the body skin.
A positive pull test showing anagen roots with thick sheaths indicates an active disease.
The scalp biopsy is decisive for the diagnosis and must be performed in an area with active disease.
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TIPS FOR TREATMENT
The treatment should be started as soon as possible in order to stop the progression of the scarring process.
Topical treatment alone is often not enough.
In patients diagnosed with frontal fibrosing alopecia (FFA) and fibrosing alopecia in a pattern distribution (FAPD) consider combining topical treatment with systemic antiandrogens.
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DON’T FORGET
Histology alone currently does not allow to differentiate the variants of LPP, do not forget to report to the pathologist the clinically based presumptive diagnosis.
The clinical presentation of lichenoid alopecias can be easily confused with androgenetic alopecia or seborrheic dermatitis.
Clinical examination and dermoscopic evidence of scarring and inflammation suggest the diagnosis.
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PITFALLS AND CAUTIONS
Diffuse variants of LPP are often misdiagnosed as seborrheic dermatitis or androgenetic alopecia, with consequent delay in the diagnosis and a progression of the irreversible fibrosis.
Lichenoid alopecias should be considered in patients with a long-standing history of erythema and itching of the scalp associated with trichoscopical signs of LPP.
A dermoscopy-guided biopsy is mandatory to confirm the diagnosis and begin the proper treatment as soon as possible.
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EXPERT PEARLS
It is essential to recognize the trichoscopical signs of LPP, such as loss of follicular ostia, perifollicular inflammation, and follicular hyperkeratosis, as they occur in all the variants of the disease. However, the distribution of involvement is the most distinctive clinical feature.
As LPP begins as a non-scarring process, if treatment is started during the early stages, partially damaged follicles can be recovered.
Based on the clinical presentation, the histological features, and the response to treatment, it could be assumed that these lichenoid alopecias could represent a variable pattern of two main diseases such as FFA and LPP. While fibrosing alopecia in a pattern distribution FAPD could be in the same spectrum of FFA, Lichen Planopilaris Diffuse Pattern (LPPDP) is more likely closer to the classical LPP.
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PATIENT EDUCATION POINTS
Patients should be warned that hair will not regrow in scarring areas.
Avoid scalp trauma due to their possible association with the development of LPP.
Some cosmetic ingredients can be a culprit and patients should be advised not to apply cosmetics on the hairline and eyebrows.
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Lichen planopilaris (LPP) is a primary lymphocytic cicatricial alopecia characterized by several different patterns of permanent hair loss....