S9C9P2-3: In this field, the mucinous changes involve the papillary dermis and the reticular dermis. Vessels are ectatic. The dermal-epidermal interface is straight, but vacuolar changes are not a prominent feature (dermatomyositis).

S9C9P2-4a&b: With a Verhoeff van Gieson stain, the epidermis is yellow; collagen bundles are red; and elastic fibers are black. The mucinosis of the dermis is associated with a reduction in both the collagenous and the elastic components of the reticular dermis. Vessels are ectatic (dermatomyositis).

S9C9P2-5: In this lesion of dermatomyositis, the epidermis shows compact hyperkeratosis and atrophy (it is thin in a vertical dimension). The epidermis, although thin, consists mostly of a hypertrophied superficial unit with no recognizable basal unit. The basal layer shows liquefaction degeneration with scattered, small lytic defects. The lesion is cell-poor at both the dermal-epidermal interface and in the perivascular spaces. The epidermal pattern at the dermal-epidermal interface is somewhat unusual. Rete ridges are preserved; they are thin with pointed extremities. The lichenoid reaction involves a sweat duct in the center of the field. The papillary dermis is widened and edematous (pale). There are clusters of necrotic keratinocytes in the keratin layer - an erythema multiforme-like or pityriasic quality).

S9C9P2-6: Lytic defects are present at the dermal-epidermal interface. To the right of the center of the field, a defect contains a necrotic keratinocyte and a few inflammatory cells. The basal layer is disorganized; the epidermis mostly shows the pattern of an atrophic superficial unit in which individual cells are hypertrophied (they have taken on the qualities of cells that are committed to terminal differentiation). The dermis shows mucinosis; collagen fibrils are randomly distributed (dermatomyositis).