A retrospective analysis of tissue-fixed immunoreactants from skin biopsies maintained in Michel's medium.

656 skin biopsies with positive direct immunofluorescence from the UK and overseas were studied over a 2-year period. The length of time biopsies had remained in Michel's medium at pH 7.0 in various diseases (pemphigoid, pemphigus, linear IgA disease, epidermolysis bullosa acquisita, lupus erythematosus, vasculitis, amyloid, lichen planus and dermatitis herpetiformis) was analysed. We concluded that direct immunofluorescence remained positive at 6 months and that Michel's medium is a reliable long-term maintenance medium for skin biopsies.