Differentials
Hypertrophic lichen planus
SIGNS / SYMPTOMS
Localised to the shins and may be surrounded by smaller, more typical lesions of lichen planus with a polygonal border and overlying Wickham striae.
INVESTIGATIONS
Skin biopsy demonstrates acanthosis and, often, irregular psoriasiform epidermal hyperplasia similar to LSC, but with additional band-like lymphocytic infiltrates and evidence of vacuolar change.
Hypertrophic actinic keratoses
SIGNS / SYMPTOMS
Lesions are typically smaller than those of LSC, located on sun-exposed areas of skin, more erythematous, and associated with greater overlying hyperkeratosis. They can be painful and are rarely associated with pruritus unless in the presence of secondary LSC.
INVESTIGATIONS
Skin biopsy demonstrates non-full thickness keratinocyte atypia, but lesions on the dorsum of the hand may show histological features of associated secondary LSC.
Squamous cell carcinoma of the skin
SIGNS / SYMPTOMS
Lesions are located on sun-exposed areas of skin, are more erythematous, often have thick overlying hyperkeratosis, and may be painful but not pruritic.
INVESTIGATIONS
Skin biopsy demonstrates keratinocyte atypia with evidence of dermal invasion.
Psoriasis
SIGNS / SYMPTOMS
Symmetrical eruption not associated with the intense pruritus of LSC. Lesions are more erythematous with silvery scales and no evidence of lichenification.
INVESTIGATIONS
Skin biopsy demonstrates regular psoriasiform epidermal hyperplasia, with confluent overlying parakeratosis and loss of the granular cell layer.
Eczema
SIGNS / SYMPTOMS
Can occur at any body site but most often occurs in flexural sites (in children and adults) or hands (in adults). Lesions of eczema are not as sharply demarcated as LSC. The pruritus of eczema can lead to LSC being superimposed on lesions of eczema.
INVESTIGATIONS
Skin biopsy demonstrates spongiosis and eosinophils.
Warts
SIGNS / SYMPTOMS
Can occur at any body site but are most commonly located on the palms and soles. Lesions are characterised by a verrucous surface with black dots and interruption of skin lines and are not associated with the intense pruritus of LSC.
INVESTIGATIONS
Skin biopsy demonstrates verrucous epidermal hyperplasia with in-toeing of the rete ridges, tiers of parakeratosis, and occasional koilocytic change.
Scabies
SIGNS / SYMPTOMS
Often a diffuse eruption with a dermatitic appearance. No burrows or scabetic nodules present on the genitalia.
INVESTIGATIONS
Skin biopsy demonstrates an intense inflammatory infiltrate extending into the deep dermis and associated with increased numbers of eosinophils.
Skin scrapings reveal intact mites, eggs, or scybala.
Mycosis fungoides
SIGNS / SYMPTOMS
Lesions are localised to areas of the body covered by a bathing suit and are more atrophic in appearance than those of LSC.
INVESTIGATIONS
Skin biopsy demonstrates a band-like infiltrate of T lymphocytes along the dermal-epidermal junction with scant epidermal spongiosis and epidermotropism.
PCR, of a skin biopsy specimen, for T-cell gene rearrangement demonstrates a monoclonal T-cell population, which is diagnostic for the condition.
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