Dermatopathology

Typical plaque with an irregular, but sharply demarcated border showing the characteristic erythema and silvery white scaling
Note the symmetrical distribution
Psoriasis

Psoriasis

Typical appearance of psoriasis. Note the engorgement of papillae and Munro microabscesses.

Lichen planus

Clinical appearance of lichen planus affecting the dorsum of the hand. One of the lesions has been biopsied.
There is hyperkeratosis, hypergranulosis, hydropic degeneration of the basal layer, and a band-like inflammatory infiltrate.


Multiple flat-topped papules with white, lacey or netlike markings (Wickham striae) are characteristic.
Lichen planus
There is a band of lymphocytes along the dermoepidermal junction (interface dermatitis). The rete ridges have acquired a pointed, or "sawtooth," architecture. The hyperkeratosis and hypergranulosis are definite signs of chronicity.

Interlacing white lines (Wickham's striae) of buccal mucosa.

Lichen planus



Acanthosis with hyperkeratosis and hypergranulosis are distinctive. Superficial dermal fibrosis with vascular ectasia is also common.
Lichen simplex chronicus