Ochronosis is the name given by Virchow in 1866 to a condition characterized by the pigmentation of the cartilages, ligaments, tendons and of the intima of the large blood vessels of the body. In this first reported case the pigment deposits appeared light gray, brown and, in places, black. On thin section, however, the pigment was everywhere found to be yellow or yellow-brown and for this reason the condition was called ochronosis.
Since then, forty additional cases have been studied. From the observations made it may be stated that ochronosis is a condition dependent on a disordered metabolism of phenol or some of its derivatives; characterized by a pigmentation of the cartilages, fibrocartilages, fibrous tissues and epidermis, as well as of areas of degeneration, notably atherosclerotic plaques, albuminous masses and concretions. A further characteristic is the presence of a dark urine due to alkapton, derivates of phenol or to melanin.