DIFFERENTIAL DIAGNOSIS
ERYTHEMA MULTIFORME
Interface vacuolar change with numerous necrotic keratinocytes
Diagnostic Pearls
* Erythematous targetoid lesions
* Lichenoid interface dermatitis with vacuolar change and intraepidermal necrotic keratinocytes.
* Subepidermal vesiculation with papillary dermal edema progressing to bullae formation.
LICHEN PLANUS
Hyperkeratosis, hypergranulosis, irregular acanthosis
Diagnostic Pearls
* Polygonal, planar, pruritic, purplish papules, present in 4th to 6th decade, more commen in women
* Compact ortho and hyperkeratosis, wedge-shaped hypergranulosis centered around acrosyringium
* Band-like infiltrate of lymphocytes (rare, if any plasma cells); necrotic keratinocytes (civatte bodies) are limited to lower epidermis
LUPUS ERYTHEMATOSIS
Discoid lupus erythemtous: Epidermal thinning, hyperkeratosis, superficial and deep dermal perivascular and peri adnexal infiltrate involving subcutaneous tissue.
Diagnostic Pearls
* Erythematous, annular scaly plaques on face, upper chest and extremities
* Superficial and deep dermal perivascular and periadnexal infiltrate may involve subcutaneous tissue
* Dermal mucin deposition
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