Delayed and persistent cutaneous reactions to coelenterates.

Three patients are described who developed firm, persistent papules and plaques at sites of previous contact with two species of coelenterates. Histologically, a predominantly mononuclear inflammatory cell infiltrate located primarily in the reticular dermis was observed with destruction of hair follicle epithelium and arrectores pilorum. Epidermal changes included focal spongiosis and exocytosis of lymphocytes. The eruptions subsided no sooner than 7 weeks from time of onset. It is hypothesized that this cutaneous reaction represents a persistent delayed hypersensitivity response to an antigenic component of the coelenterate nematocyst.