Lichenoid dermatoses

Eruptive lichenoid papules with wide distribution, heals with hyperpigmentation; self-limited (typically resolves within 9 months)

Photosensitive variant of LP with melasma-like appearance or lichenoid papules over face, neck and dorsal hands; typically in children and young adults with spring or summer onset (some consider entity as lichenoid form of polymorphous light eruption {PMLE})

Annular papules and plaques with central clearing (commonly over penis)

Lichenoid papules replaced with depressed atrophic areas typically over lower legs, ± residual hyperpigmentation; resembles lichen sclerosus clinically

Vesicles and bullae arising within existing LP lesions (intense inflammatory reaction at dermoepidermal junction causes subepidermal bullae)

Distribution typically generalized or sun-exposed sites; Wickham’s striae uncommon; ± eosinophils and parakeratosis on histology; medication typically taken for several months before eruption appears

{Common meds: β-blockers, captopril, penicillamine, HCTZ, antimalarials, furosemide, quinidine, NSAID, tetracycline, quinacrine, gold, sulfonylureas, hydroxyurea, methyldopa}

Painful, chronic, recalcitrant erosive lesions especially on oral mucosa and palmoplantar surface; small ↑ risk of SCC within longstanding lesions; erosive oral LP associated with liver disease (HCV)

Seen in up to 20% of LP patients; glans penis common site for men (annular lesions, small grouped papules, or larger plaques); vulvar LP commonly erosive and may coexist with gingival involvment (‘vulvovaginal gingival syndrome’)

Thick, hyperkeratotic intensely pruritic plaques commonly found over shins or dorsal feet; also known as LP verrucosus

LP lesions in groin, axillae and inframammary regions

Linear groups of lichenoid papules following lines of Blaschko

Up to 50% patients with skin disease may have oral mucosal changes; ranges from reticular, atrophic, erosive, bullous, papular to pigmented; reticular type most common with lacy white hyperkeratosis on buccal mucosa, lips, tongue and gingiva; typically asymptomatic unless erosive; rarely may see esophageal, laryngeal or conjunctival involvement

10% of LP patients; may be isolated finding; typically lateral nail thinning, longitudinal ridging, dorsal pterygium, splitting, ± 20 nail dystrophy

Clinical and histologic features of both lupus erythematosus (LE) and LP

Painful hyperkeratotic yellow to erythematous plaques on palms and soles (lateral borders and pressure points), ± ulceration, erosions; recalcitrant to therapy

Tense vesicles and bullae arise in normal, uninvolved skin; typically blisters occur weeks to months after appearance of typical LP lesions; overlap between bullous pemphigoid and LP; + IgG antibody to BP180 (NC16A)

{DIF: linear IgG/C3 at BMZ IIF: IgG at roof of blister (salt-split skin)}

Gray-brown macules in sun-exposed areas ± flexural folds in darker-skinned patients; similar to erythema dyschromicum perstans

Keratotic follicular papules with violaceous rim leading to cicatricial alopecia

{Graham-Little-Piccardi-Lasseur syndrome: typical skin/mucous membrane LP, scarring alopecia of scalp, nonscarring loss of pubic/axillary hairs}