Parry-Romberg syndrome (PRS), also known as progressive facial hemiatrophy or idiopathic hemifacial atrophy, is a rare disorder that presents as slowly progressive atrophy of one half of the face. Skin and subcutaneous tissue atrophy may be accompanied by atrophy of muscle, cartilage, or bone. PRS commonly involves one or more of the trigeminal nerve branches. Severe disease is characterized by atrophy affecting the structures supplied by all 3 branches. Rare bilateral involvement and extrafacial involvement (such as the arm, leg, or trunk) has been reported.

The tongue and salivary glands may be affected. Associated neurologic and ophthalmic involvement may include migraine headaches, seizures, trigeminal neuralgia, enophthalmos, and eyelid dysfunction.

PRS typically develops in the first or second decade and is more common in females. It occurs spontaneously with no known preceding exposures or genetic predisposition, and is believed to be mediated by autoimmune factors. This syndrome may have an insidious onset and is slowly progressive, ultimately stabilizing after 2-20 years.