Title: GZ / The Grenz Zone Season 1 / Episode 10
Tags: GZ DermnetNZ

Q: What are the 6 P's of lichen planus?
[...]
A: Pruritic, purple, polygonal, planar papules and plaques

Q: Lichen planus often presents with [...], which are fine grey-white dots or a net-like pattern overlying the lesions
A: wickham striae
Back Extra: Best appreciated in the oral mucosa

Q: Most common site for lichen planus?
[...]
A: Oral mucosa
Back Extra: Only 10% of patients w/ oral lichen planus go on to manifest the stereotypical skin findings

Q: [...] of lichen planus often appears in a linear distribution, as patients induce new LP lesions to sites of trauma by scratching the pruritic lesions
A: Koebnerization
Back Extra: Other skin lesions known to exhibit koebnerization include psoriasis and vitiligo

Q: What is the difference between koebnerization and pathergy?
[...]
A: Koebernization refers to new lesions appearing at areas of trauma, whereas pathergy means that a non-specific ulcer appears at sites of trauma
Back Extra: Pathergy seen in Behçet's disease and pyoderma gangrenosum
Pathergy of LP

Q: Skin manifestations of lichen planus often occur on the [...] and [...], as well as the hands, shins,
neck, sacrum, and genitals
A: anterior forearms; wrists
Back Extra: May also be generalized

When categorizing lichen planus variants based on location, LP variants can be broken down into
Genital LP
Mucosal LP
Inverse LP
Nail LP
Palmoplantar LP
Lichen planopilaris
Back Extra: Nail
Palmoplantar
Inverse
LPP

Q: Genital lichen planus in males can present as classic LP lesions or have a(n) [...] plaque on the glans of the penis or shaft
Women with genital LP can have debiliatating erosive lesions in the vulva and within the vagina, and often present with oral findings as well [...]
A: annular; vulvovaginal gingival syndrome

Q: Mucosal lichen planus affects 50% pts with cutaneous LP and can be caused by [...] containg amalgams or [...] fillings
A: mercury; gold
Back Extra: Don't confuse mucosal LP with a horizontal line from a bite

Q: Oral lichen planus should make you slightly more suspicious for [...] induced lichen planus, especially if areas outside of the buccal mucosa are affected
A: hepatitis C
Back Extra: In addition, erosive, atrophic, and bullous oral LP may make you suspicious of esophageal involvement, warranting the need to monitor for progression to squamous cell carcinoma

Nail changes of lichen planus may include lateral thinning, longitudinal ridges (onychorrhexis), pitting, twenty nail dystrophy (trachyonychia), and dorsal pterygium
Back Extra: Pterygium
Trachyonychia

Q: [LP variant]: erythema and perifollicular scale around the hair follicle on the scalp.  Can lead to scarring alopecia
A: Lichen Planopilaris

Q: [...] syndrome presents with scarring alopecia of the scalp caused by lichen planopilaris, non-scarring hair loss at the pubic and axillary regions, follicular papules that appear as keratosis pilaris and classic lichen planus lesions of the skin and the mucosa
A: Graham-Little-Piccardi-Lasseur

When grouping lichen planus variants by cause, lesions are categorized as
1. actinic, which occurs in young middle-eastern adults and presents as red/brown plaques on the sun-exposed areas of the face, neck, and extremities, and
2. Drug-induced, which presents later in life as generalized lesions that are more eczematous and photo-distributed than classic LP. In addition, wickham striae are absent, and the mouth and genitals are spared in this variant
Back Extra: Drug induced LP shown; remember that this reaction can be delayed by up to 1 year

Q: What drugs are some classic culprits of a drug-induced LP?
[...]
A: β blockers, ACE-inhibitors, NSAIDs, gold, HCTZ, antimalarials (hydroxychloroquine)
Back Extra: TNF- alpha inhibitors may cause this as well
In general, think blood pressure medications
Notice that many of the same drugs that cause drug-induced pityriasis rosea cause drug-induced LP!

When categorizing lichen planus variants based on appearance, LP variants can be broken down into
Classic
Acute or exanthematous: Rapidly diffuse lesions that resolve in 3-9 months
Annular: Typically affects the penis or axilla
Atrophic: Depressed hyperpigmented lesions that typically appear on the legs
Ulcerative: Tends to affect the palmoplantar surfaces

Cont...When categorizing lichen planus variants based on appearance, LP variants can be broken down into
Hypertrophic: Thick scaly plaques on the shins and dorsal feet that are often symmetric, very pruritic and can be confused with pickers nodules
Bullous: blisters that arise within chronic LP lesions
Pemphigoides: blisters arise mostly on uninvolved skin
Pigmentosus: Seen as grey-brown macules on sun exposed areas of the face and neck w/ darker Fitzpatrick skin types 3, 4
Back Extra: Pigmentosus

Lichen planus pemphigoides involves IgG auto-antibodies targeting BP antigen 2 of the basement membrane (also targeted in bullous pemphigoid and herpes gestationis (pemphigoid gestationis))
Back Extra: Bullous pemphigoid
Herpes gestationis

Q: Ashy dermatosis and lichen planus pigmentosus appear similar, but one hint is that [...] typically arises in teens-20s, whereas [...] occurs in the 30s and 40s y/o
A: Ashy dermatosis; lichen planus pigmentosus

Histology of classic lichen planus
Compact hyperkeratosis without parakeratosis and eosinophils
Hyper-granulosis
Irregular acanthosis with sawtooth rete ridges
Dense lichenoid lymphocytic infiltrate leading to development of civatte bodies (apoptotic keratinocytes) or Max-Joseph spaces (separation between dermis and epidermis)
Back Extra: Eosinophils? Think drug-induced LP
If Max-Joseph spaces get large enough, it can lead to bullous lichen planus

Q: Treatment options for lichen planus
Classic LP: [...]
Oral or genital LP: [...]
Hypertrophic lesions: [...]
A: topical corticosteroids; topical calcineurin inhibitors (pimecrolimus or tacrolimus); intralesional Kenalog
Back Extra: Generalized LP more complicated Prednisone 20 mg multiple weeks w/ taper, Intramuscular
kenolog, low dose methotrexate, metronidazole 500mg BID, phototherapy (UVB or PUVA)
Acitretin or cyclosporine as last resort