Lichenoid Interface Dermatitis

Key Features:

■ Dense, band-like inflammatory cell infiltrate, which obscures the dermoepidermal junction

■ Infiltrate may be only in the superficial dermis, or both the superficial and deep dermis

LICHENOID INTERFACE DERMATITIS—SUPERFICIAL

LICHEN PLANUS Clinical Presentation:

■ Chronic dermatosis with skin, hair follicle, and mucous membrane involvement; 10% of cases show involvement of the nail unit, often with pterygium formation

■ Presents clinically as pruritic, violaceous, flat-topped, polygonal papules, and plaques

■ Sites of predilection include inner aspects of wrists, flexor forearms, anterior thighs and the shins; lichen planopilaris (follicular lichen planus) primarily affects the scalp

■ There is a reported association with hepatitis C seropositivity

Histology:

■ Compact orthokeratosis (Figs. 8A and B)

■ Wedge-shaped hypergranulosis (Fig. 8B)

■ Jagged, "saw-tooth" acanthosis of the epidermis (Fig. 8B)

■ Band-like, superficial lymphocytic infiltrate which obscures the dermoepidermal junction (Figs. 8A-C)

■ Necrotic keratinocytes in the lower one-third of the epidermis (Fig. 8D)

■ Civatte bodies: homogeneous, eosinophilic globules (representing apoptotic keratinocytes) in the lower epidermis and in the papillary dermis (Fig. 8D)

■ A.K.A.: colloid bodies: periodic acid Schiff (PAS)-positive, diastase-resistant

■ Max-Joseph spaces: small sub-epidermal clefts secondary to damage to basal keratinocytes

Immunofluorescence: Direct Immunofluorescence:

■ Colloid bodies stain positively for complement and immunoglobulins, mainly IgM

■ There is an irregular band of staining for fibrin along the basement membrane zone

Differential Diagnosis:

Lichen Planus

Lichenoid Drug Eruption

Parakeratosis is not a feature

Parakeratosis is frequently present

Band-like infiltrate is

Band-like infiltrate is mixed and

lymphohistiocytic

often contains eosinophils

Necrotic keratinocytes are usually

Necrotic keratinocytes are found in

limited to the lower one-third of the

all layers of the epidermis

epidermis

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