Skin nontumor

Alopecia

Lichen planopilaris



Last author update: 16 January 2024
Last staff update: 16 January 2024

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PubMed Search: Lichen planopilaris

Pooria Zare, M.D., M.P.H.
Mazaher Ramezani, M.D.
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Cite this page: Zare P, Ramezani M. Lichen planopilaris. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorlichenplanopilaris.html. Accessed February 26th, 2024.
Definition / general
  • Lichenoid inflammation around the hair follicle
Essential features
  • Most common scarring alopecia in White populations; discoid lupus erythematosus (DLE) and central centrifugal cicatricial alopecia (CCCA) predominate in richly pigmented populations (Am J Dermatopathol 2023;45:532)
  • Involvement of the infundibuloisthmic area of the hair structure with lymphocytic infiltration
  • Perifollicular mucinous fibroplasia
  • 3 variants
    • Classic lichen planopilaris (LPP)
    • Frontal fibrosing alopecia (FFA)
    • Graham-Little-Piccardi-Lassueur syndrome (GLPLS)
Terminology
  • Follicular lichen planus
  • Frontal fibrosing alopecia (FFA)
  • Graham-Little-Piccardi-Lassueur syndrome (GLPLS)
ICD coding
  • ICD-10: L66.1 - lichen planopilaris
Epidemiology
  • F > M
  • Middle age > others
  • Most commonly occurs in White patients, followed by Black patients and then patients of other races (Int J Womens Dermatol 2018;4:180)
Sites
  • LPP: scalp (more common in the vertex and parietal scalp)
  • FFA: frontotemporal with or without eyebrows, sideburns in males, limbs in both
  • GLPLS: scalp (scarring alopecia), axilla and groin (nonscarring alopecia), trunk and extremities (hyperkeratotic follicular papules)
  • References: An Bras Dermatol 2022;97:348, Front Med (Lausanne) 2021;8:737813
Pathophysiology
  • Not completely understood
  • Loss of immune privilege in hair follicle stem cells
  • Autoimmune follicular damage by CD8+ T cell dominant lymphocytic infiltration
  • Disruption of peroxisome proliferator activated receptor gamma (PPARĪ³) and its lipid mediator stimulants
  • Epidermal - mesenchymal transition
  • FOXP3 overexpression
  • Mitochondrial malfunction
  • Increase in M2 macrophages: LPP > FFA
  • References: J Clin Med 2023;12:3259, JID Innov 2022;2:100113
Etiology
Clinical features
  • LPP (JID Innov 2022;2:100113, J Clin Med 2023;12:3259, Int J Trichology 2013;5:204)
    • Asymmetric, single or multifocal patches of scarring alopecia
    • Perifollicular erythema
    • Follicular scar
    • Follicular spine (plugging)
    • Symptoms: pruritus, burning or pain
    • Trichoscopy: diminished follicular ostia, perifollicular white scales and erythema, white dots, blue-gray dots with target pattern around follicles
    • Lichen planopilaris activity index (LPPAI) is used for quantification of symptoms and signs (J Am Acad Dermatol 2010;62:387)
  • FFA (JID Innov 2022;2:100113, J Clin Med 2023;12:3259)
    • Facial and extrafacial keratotic papules
    • Involvement of androgenetic dependent areas
    • Postmenopausal hair loss along the frontotemporal hairline and the eyebrows
    • Symmetric
    • Symptoms: pruritus, burning or pain
    • Trichoscopy: diminished follicular ostia, perifollicular white scales and erythema
    • Frontal fibrosing alopecia severity index (FFASI) is validated for assessing FFA (Br J Dermatol 2016;175:203)
    • Frontal fibrosing alopecia severity score (FFASS) is also validated for assessing FFA (J Am Acad Dermatol 2018;78:522)
  • GLPLS (An Bras Dermatol 2022;97:348)
    • Triad
      • Scarring alopecia of the scalp
      • Nonscarring alopecia of axilla and groin
      • Follicular papules on trunk and extremities
Diagnosis
Prognostic factors
  • Generally can be resistant to treatment
  • Some cases improve spontaneously or with treatment
  • Others last for years
  • Reference: Am Fam Physician 2011;84:53
Case reports
Treatment
  • Goal: to improve symptoms and stop progression of the alopecia
  • No written guidelines
  • Recommended therapies
    • LPP (Clin Cosmet Investig Dermatol 2018;11:91, An Bras Dermatol 2022;97:348)
      • Limited: topical / intralesional steroids
      • Extensive
        • Systemic treatment: hydroxychloroquine, methotrexate, cyclosporine, mycophenolate mofetil, pioglitazone and tofacitinib
        • Topical / intralesional steroids: if limited active lesions are present
        • Systemic steroids: only in severe cases to improve symptoms and stop rapid progression
    • FFA (An Bras Dermatol 2022;97:348)
      • Topical / intralesional steroids
      • Systemic treatment: 5 alpha reductase inhibitors, hydroxychloroquine, retinoids, etc.
Clinical images

Images hosted on other servers:
Frontotemporal and eyebrow alopecia (FFA) and Multifocal scalp alopecia (LPP)

Frontotemporal and
eyebrow alopecia
/ multifocal scalp
alopecia

Trichoscopic view of LPP

Trichoscopic view

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Pooria Zare, M.D., M.P.H. and Mazaher Ramezani, M.D.
Inflammation

Inflammation

Tufting Tufting

Tufting

Infundibuloisthmic involvement Infundibuloisthmic involvement

Infundibuloisthmic involvement


Upper follicular involvement Upper follicular involvement Upper follicular involvement

Upper follicular involvement

Scar Scar

Scar


Follicular plugging

Follicular plugging

Follicular lichenoid inflammation

Follicular lichenoid inflammation

Lymphohistiocytic infiltrate  and mucin

Lymphohistiocytic infiltrate and mucin

Immunofluorescence description
  • Could be positive in
    • Colloid bodies containing IgM or IgG in the dermis around follicular epithelium, with globular or clustered pattern (not linear)
    • Papillary dermis with irregular depositions of C3 or fibrinogen
  • Reference: An Bras Dermatol 2022;97:348
Positive stains
Negative stains
Sample pathology report
  • Skin, scalp, punch biopsy:
    • Lymphocytic scarring alopecia compatible with lichen planopilaris (see comment)
    • Comment: Infundibuloisthmic involvement and perifollicular mucinous fibroplasia are features in favor of diagnosis. Clinicopathologic correlation is recommended.
Differential diagnosis
  • Discoid lupus erythematosus (DLE):
    • Interfollicular epidermal involvement with lichenoid inflammation or vacuolization
    • Thick and tortuous epidermal basement membrane
    • Patchy lymphoplasmacytic infiltration of the superficial and deep (periadnexal and perivascular) dermis
    • Interstitial mucin deposition
    • Perieccrine inflammation
    • Dermal clusters of CD123 positive plasmacytoid dendritic cells
  • Folliculitis decalvans:
    • Mixed neutrophilic and lymphoplasmacytic inflammation
    • Absence of interface change in dermoepidermal junction
  • Central centrifugal cicatricial alopecia:
    • Mixed neutrophilic and lymphocytic inflammation
    • Syringoma-like dilated eccrine ducts (nonspecific, may be seen in other scarring alopecias; clinicopathologic correlation is necessary) (Am J Dermatopathol 2017;39:668)
  • Pseudopelade of Brocq:
    • End stage scarring alopecia
    • Most common cause of this disease is LPP
Board review style question #1

Which of the following features is most typical in the above case of lichen planopilaris (LPP) / frontal fibrosing alopecia (FFA)?

  1. Extension of inflammation to the subcutis
  2. Follicular tufting
  3. Involvement of the upper portion of the follicle
  4. Presence of miniaturization of hairs
Board review style answer #1
C. Involvement of the upper portion of the follicle. The picture shows a case of lichen planopilaris with involvement of the upper portion of the follicle, which is a hallmark of the disease. Answer D is incorrect because miniaturization of hairs is mostly seen in androgenetic alopecia and is not a feature of classic LPP. Answer B is incorrect because follicular tufting may be seen in LPP but it is also observed in other cases with follicular invasion by inflammatory cells, including folliculitis decalvans. Answer A is incorrect because the extension of inflammation to the subcutis is not a prominent feature in LPP; it is more commonly seen in discoid lupus erythematosus (DLE).

Comment Here

Reference: Lichen planopilaris
Board review style question #2
What is the most common cause of lymphocytic scarring alopecia in White predominant populations?

  1. Discoid lupus erythematosus
  2. Folliculitis decalvans
  3. Lichen planopilaris
  4. Pseudopelade of Brocq
Board review style answer #2
C. Lichen planopilaris. The most common cause of lymphocytic scarring alopecia is classic lichen planopilaris (LPP). Answer A is incorrect because discoid lupus erythematosus (DLE) is one of the examples of lymphocytic scarring alopecia but it is not the most common. It is associated with patchy lymphoplasmacytic infiltration of the superficial and deep dermis, including periadnexal and perivascular areas. Answer D is incorrect because pseudopelade of Brocq represents end stage scarring alopecia, mainly characterized by the absence of inflammation. Answer B is incorrect because folliculitis decalvans involves follicles with inflammatory cells, including lymphocytes, neutrophils and plasma cells.

Comment Here

Reference: Lichen planopilaris
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