Collagen diseases.

Dermatomyositis and variants of lupus erythematosus share histopathologic features which include liquefaction degeneration of the epidermal basal zone, melanin pigment incontinence, and the presence of colloid bodies. The pattern of epidermal changes and dermal inflammation help establish the correct diagnosis. Immunofluorescence microscopy of skin biopsies is useful in confirming the diagnosis.