Etretinate is a synthetic retinoid compound, chemically known as the ethyl ester of a polyene carboxylic acid derivative. It is primarily used in dermatology for the treatment of severe psoriasis and other hyperkeratotic skin disorders by modulating epidermal cell proliferation and differentiation. Due to its potent teratogenic effects and long biological half-life, etretinate is contraindicated during pregnancy and has been discontinued or restricted in many markets worldwide. It is available as a high-purity reference standard for pharmaceutical research and analytical purposes.