1.Psoriasiform only

1)Lymphocyte predominate

               Spiraled capillaries in thin dermal-----Psoriasis
               papillae,rete ridges of uniforrm length.
               some rete ridges thinned

               Rete ridges of uneven lengths. ---------Allergic contact derrnatitis/
               parakeratosis. no spiraled                       Nummular dermatitis/
               capillaries in dermal papillae                 Dyshidrotic dermatitis, late

               Checkerboard pattern of --------------Pityriasis rubra pilaris
               orthokeratosis and parakeratosis

               Scale-crust at lips of infundibular------Seborrheic dermatitis
               ostia

               Hyphae in cornified layer---------------Dermatophytosis

               Pseudohyphae in cornified layer---------Candidiasis

               Hyperkeratosis, hypergranulosis.--------Lichen simplex chronicus/
               coarse collagen bundles often                   Prurigo nodularis/
               perpendicular to skin surface in               Acanthoma fissuratum/
               thickened papillary dermis                       Pressure papule from prosthesis/
                                                                                Surfer's nodules/
                                                                                Chondrodermatitis  nodularis helicis

 

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2.Lichenoid

1)Lymphocyte predominate

                Lymphocytes along adnexal -------------Lichen striatus
                structures in reticular dermis.
                individual necrotic keratinocytes

                Wiry bundles of collagen in--------------Mycosis fungoides, plaque 
                haphazard array in upper part of dermis,
                lymphocytes numerous in epidermis with
                scant spongiosis

               Stubby zones of parakeratosis and --------Inflarmmatory linear verrucous
               no granular zone beneath them                     epidermal nevus

1)Histiocytes and plasma cells predominate
               Syphilis. secondary