Achromia

ACHROMIA (from Greek a - negative particle, and chroma - color), discoloration of the skin, can be hereditary (see Albinism) and acquired (vitiligo); it appears in the form of small round white spots, with sharp outlines and a tendency toward peripheral growth, surrounded by a zone of hyperpigmentation; the process can spread to almost the entire surface of the skin, excluding the palms and soles; the arrangement is often symmetrical; the hair often becomes discolored along with the skin. Sometimes A. is combined with patchy baldness and scleroderma. Histologically, the absence of pigment is noted in the center of the spots and thickening at the periphery; otherwise the skin is normal. The etiology of A. is unclear, with trauma, injury, peripheral neuritis, tabes, tumors, meningitis, Basedow's disease, damage to the cervical sympathicus [the famous experiment of Achard], etc., cited as causes.