An inflamatory disease of the skin beginning usually upon the scalp and characterized by scaliness, redness, and fatty hypersecretion, with a tendency to downward extension. The malady may be acute, subacute or chronic, varying widely in intensity and appareance and tending chiefly to affect certain sites of election but also spreading from these. The eruption ranges from localized, scarcely erythematous, furfuraceous patches, to severe erythematous causing widespread lesions, and from intertrigos of varying severity to petaloid chronic localized yellowish-pink lesions with greasy scales; seborrheic folliculitis is also recognized. The affected individuals manifest a diathesis which has been named the seborrhoeic state.