Parry–Romberg syndrome (PRS) is a rare disease presenting in early childhood[1] characterized by progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face (hemifacial atrophy) but occasionally extending to other parts of the body.

[2] An autoimmune mechanism is suspected, and the syndrome may be a variant of localized scleroderma, but the precise cause and pathogenesis of this acquired disorder remains unknown.

The disease progressively spreads from the initial location, resulting in atrophy of the skin and its adnexa, as well as underlying subcutaneous structures such as connective tissue, (fat, fascia, cartilage, bones) and/or muscles of one side of the face.

[4][5] The syndrome often begins with a circumscribed patch of scleroderma in the frontal region of the scalp which is associated with a loss of hair and the appearance of a depressed linear scar extending down through the midface on the affected side.

[4] Half of these cases are associated with abnormalities in both the gray and white matter of the brain—usually ipsilateral but sometimes contralateral—that are detectable on magnetic resonance imaging (MRI) scan.

Other common findings include drooping of the eyelid, constriction of the pupil, redness of the conjunctiva, and decreased sweating of the affected side of the face.

Other ocular abnormalities include ophthalmoplegia (paralysis of one or more of the extraocular muscles) and other types of strabismus, uveitis, and heterochromia of the iris.

35% have difficulty or inability to normally open the mouth or other jaw symptoms, including temporomandibular joint dysfunction and spasm of the muscles of mastication on the affected side.

[13] Several instances have been reported where more than one member of a family has been affected, prompting speculation of an autosomal dominant inheritance pattern.

[14] Various other theories about the cause and pathogenesis have been suggested, including alterations in the peripheral sympathetic nervous system (perhaps as a result of trauma or infection involving the cervical plexus or the sympathetic trunk), as the literature reported it following sympathectomy, disorders in migration of cranial neural crest cells, or chronic cell-mediated inflammatory process of the blood vessels.

A diagnostic lumbar puncture and serum test for autoantibodies may also be indicated in people who present with a seizure disorder of recent onset.