A case of circular eczematous dermatitis around seborrheic keratosis was presented. A 54-year-old man presented with two weeks history of a round pruritic eruption around a preexisting lesion of seborrheic keratosis. Microscopic findings showed central tumor nest composed mainly of basaloid cells with occasional spongtosis and exocytosis. A diffuse, dense, mononuclear cell infiltrate with increased contents of melanophages was seen beneath the tumor. The surrounding lesion of halo dermatitis showed mild dilatation of the capillaries and perivascular infiltration of mononuclear cells in the upper and mid-dermis.