Acantholysis is the loss of cohesion between epidermal (or epithelial) cells leading to the formation of intraepidermal clefts, vesicles, or bullae. Primary acantholysis results from dissolution or separation of the desmosomes between unaltered cells. Secondary acantholysis occurs between damaged cells such as during viral infection. An example of primary acantholysis in pemphigus vulgaris is shown.