Lichen Planus



Lichen Planus

Definition:
Lichen planus is an acute or chronic inflammatory dermatosis involving skin and/or mucous membranes, characterized by flat-topped, pink to violaceous, shiny, pruritic polygonal papules on the skin and milky white reticulated papules in the mouth.

The term ‘lichenoid’ is used by clinicians to describe a flat-topped, shiny, papular eruption resembling lichen planus (LP), or by histopathologists to describe a type of tissue reaction consisting principally of basal cell liquefaction and a band-like inflammatory cell infiltrate in the papillary dermis 4.

6 Ps:
1. Pruritic
2. Purple.
3. Polygonal.
4. Polished.
5. Planar.
6. Papules/plaques.

Other P: Pletiful 3.

Epidemiology:
Age of onset: 30 to 60 years.
Sex: Females > Males 1, Male = Female 2.
Race: Hypertrophic LP > Blacks.
Prevalence: Estimated < 1% of general population, Worldwide 0.14% to 0.80%, US 0.44% 2.

Etiology and pathogenesis:
1. Idiopathic.
2. Cell-mediated immunity plays a major role.
3. Majority of lymphocytes in infiltrate are CD8+ and CD45Ro+ (memory) cells, and express the  α-β T-cell receptor (TCR).
4. Association:
a. Drug.
b. Metal.
c. Infections: Hepatitis C (contradictory data).
d. HLA: HLA-B7 (familial), HLA-A3 (non-familial), HLA-B8 (oral), HLA-Bw35 (cutaneous).
e. Graft-versus-host disease.
5. Risk factors: Anxiety, depression 4.

Physical examination:
SKIN (Classic type):
1. Symmetric, grouped, erythematous to violaceous, polygonal, flat-topped, papules, 1 to 10 mm, sharply defined, shiny, with lacy white network lines (Wickham's striae).
2. Dark-skinned individuals, post-inflammatory hyperpigmentation is common.
3. Scratching, injury or trauma may induce isomorphic (Koebner) response.
4. Sites of predilection: Wrists (flexor), lumbar, shins (thicker, hyperkeratotic lesions), scalp, glan penis, mouth.

Variants: 2
1. Hypertrophic LP.
2. Atrophic LP.
3. Vesiculobullous LP.
4. Erosive and ulcerative LP.
5. Follicular LP (Lichen plano-pilaris).
6. Actinic LP.
7. Lichen Planus Pigmentosus.
8. Other rare variants: Perforating, Guttate, Exfoliative, Exanthematous, Invisible.

Graham-Little-Piccardi-Lassueur (or Graham-Little-Feldman) syndrome
Triad of:
1. Follicular LP (lichen planus spinulosus).
2. Multifocal cicatricial alopecia of scalp.
3. Non-scarring alopecia of axillar and pubic areas.

MUCOUS MEMBRANE:
1. 40-60% patients with LP have oropharyngeal involvement.
2. Types: Reticular LP, Erosive or ulcerative LP, Plaque-like, Atrophic, Papular, Bullous.

GENITALIA:
Papular, annular, or erosive lesions arise from penis (especially glan), scrotum, labia majora/minora, vagina.
1. Male: 25% cases, > glan penis, annular lesions frequent.
2. Female: Patches of leukoplakia or erythroplakia, sometimes erosion or generalized desquamative vaginitis.

SCALP:
Atrophic scalp with scarring alopecia.

NAILS:
1. 10-15%.
2. Destruction of nail fold and nail bed with longitudinal splintering/ridging, and distal splitting of nail plate (onychoschizia).
3. Others: Onycholysis, longitudinal striation (onychorrhexis), subungual hyperkeratosis,or even absence (anonychia). Irregular pitting. Rarely twenty-nail dystrophy (trachyonychia).
4. Pterygium or forward growth of the eponychium with adherence to the proximal nail plate is a classic finding.

Differential diagnosis of LP 2:
A. Classic.
1. Psoriasis.
2. Drug eruption.
3. Lichen simplex chronicus.
B. Annular.
1. Granuloma annulare.
2. Tinea.
C. Linear.
1. Nevus unius lateris.
2. Lichen striatus.
3. Linear epidermal nevus.
D. Hypertrophic.
1. Lichen simplex chonicus.
2. Prurigo nodularis.
3. Lichenoid cutaneous amyloidosis.
4. Kaposi sarcoma.
E. Atrophic.
1. Lichensclerosus.
F. Follicular.
1. Lichen nitidus.
2. Lichen spinulosus.
G. Childhood.
1. Lichen nitidus.
2. Lichen striatus.
3. Pityriasis lichenoides.
4. Papular acrodermatitis of childhood.

Lichen planus-like eruptions:
(Closely mimic typical LP, both clinically and histologically)
1. Chronic GVHD.
2. Dermatomyositis.
3. Cutaneous manifestation of malignant lymphoma.
4. Drugs.

Special forms of lichen planus or lichenoid eruptions: 2
1. Drug-induced lichen planus.
2. Lichen planus-Lupus erythematosus overlap syndrome.
3. Lichen planus pemphigoides.
4. Keratosis lichenoides chronica (Nekam disease).
5. Lichenoid reaction of graft-versus-host disease.
6. Lichenoid keratosis.
7. Lichenoid dermatitis.

Dermatopathology: 1,2,3
1. Epidermis shows hyperkeratosis, irregular acanthosis and elongation of rete ridges resembling sawtooth pattern. No parakeratosis.
2. Increased granular layer (Wedge-shaped hypergranulosis).
3. Liquefaction degeneration of basal cell layer (interface reaction).
4. Band-like mononuclear/lymphocytic infiltrate is seen in papillary dermis that abuts the epidermis.
5. Degenerate keratinocytes (colloid, Civatte bodies) are found in the dermal-epidermal junction.
6. The rete ridges may appear flattened or effaced (‘saw-tooth’ appearance), and focal separation from the dermis may lead to Max Joseph spaces 4.
7. Epidermal melanocytes are absent or considerably decreased in number, while pigmentary incontinence with dermal melanophages is characteristic 4.
8. Direct immunofluorescence reveals heavy deposits of fibrin at the junction and IgM and, less frequently, IgA, IgG, and C3 in the colloid bodies.

Features that may be seen in lichenoid drug eruption but not in LP 2:
1. Abundant plasma cells and eosinophils in the infiltrate.
2. Focal parakeratosis and hypogranulosis.
3. Presence of cytoid bodies high in stratum corneum.
4. Lymphocytic infiltration is less dense and not as band-like as that seen in classic LP.

Management:1
A. Topical therapy:
1. Glucocorticoids.
2. Cyclosporine.
3. Tacrolimus solution.

B. Systemic:
1. Glucocorticoids.
2. Cyclosporine (5mg/kg).
3. Retinoids: Acitretin 1 mg/kg/day, Isotretinoin 20-40mg/day.

C. PUVA photochemotherapy.

D. Others:
1. Mycophenolate mofetil.
2. Hydroxychloroquine.
3. Azathioprine.
4. Dapsone.
5. Cyclophosphamide.
6. Interferons-α 2b
7. Metronidazole.
8. Doxycycline, tetracycline and nicotinamide.
9. Heparin analogues (Enoxaparin).
10. Thalidomide 2.

Prognosis:
1. Persists for months/years.
2. Relapse of disease in 15-20%.
3. Incidence of oral cancer (squamous cell carcinoma) increased by 5% in oral LP.
4. Poor prognosis;
a. Scarring alopecia.
b. Isolated mucosal involvement.
c. Subtypes: Ulcerative, palmo-plantar, actinic.

Agents inducing Lichen Planus and Lichenoid Reactions 1:

Common inducers
Less common inducer:
Commonly prescribed
Less common inducers:
Uncommonly prescribed.
Gold salts
Beta blockers.
Antimalarials.
Thiazide diuretics.
Furosemide.
Spironolactone.
Penicillamine.
ACE inhibitors.
Calcium channel blockers.
Sulfonylurea.
NSAIDs.
Ketoconazole.
Tetracycline.
Phenothiazine derivatives.
Methyldopa.
Anti-tubercular.
Sulfasalazine.
Heavy metals (arsenic, mercury).
Lithium.
Iodides and radiocontrast media.
Antimoni.
Carbamazepine.

Treatment for Cutaneous Lichen Planus 2:


Topical
Physical
Systemic
First line
1. Topical steroids 1-2/day.
2. Intralesional steroids 5-20mg/ml.
3. Tacrolimus.
4.Pimecrolimus.
PUVA
1. Systemic steroids,  30-80mg/day.
2. Etritinate,  10-75mg/day.
3. Acitretin,  30mg/day.
4. Isotretinoin,  20-40mg/day.

Second line


1. Cyclosporin,  3-10mg/kg/day.
2. Dapsone,  200mg/day.
3. Hydroxychloroquine,  200-400mg/day.
4. Azathioprine.
5. Mycophenolate mofetil,  1500mg BD.

Special forms


1. Doxycycline, tetracycline, & nicotinamide (LP pemphigoides).
2. Interferons-α 2b (Generalized).
3. Metronidazole (Generalized).
4. Cyclophosphamide (Refractory LP).
5. Methotrexate (Refractory LP).


Treatment for Oral Lichen Planus 2:


Topical
Physical
Systemic
1st line
1. Topical steroids.
2. Lidocaine.
3. Intralesional steroids.
4. Tretinoin gel.
5. Isotretinoin gel.
6. Tacrolimus.
7. Pimecrolimus.
1. Extracorporeal   
    photochemotherapy.

2. Photodynamic therapy.
1. Systemic steroids.
2. Retinoids: Acitretin, Isotretinoin.
3. Anti-candidal.
2nd line
Cyclosporin mouth wash.

1. Cyclosporin.
2. Griseofulvin.
3. Hydroxychloroquine.
4. Thalidomide.
5. Azathioprine, Mycophenolate mofetil.
6. Cyclophosphamide.


References:
1. Fitzpatrick's Color Atlas & Synopsisnof Clinical Dermatology, 5th ed. McGraw Hill. 2005, pg 123-127.
2. Fitzpatrick's Dermatology in General Medicine, 7th ed. McGraw Hill. 2008, pg 244-255.
3. Dermatology Secrets in Color, 3rd ed. Fitzpatrick, Morelli. Mosby-Elsevier. 2007, pg 98-104.
4. Rook’s Textbook of Dermatology, 7th edition, Blackwell Publishing, 2004;42.1.




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