Progressive facial hemiatrophy is a rare disease, especially in childhood. Of extremely rare occurrence is crossed hemiatrophy.
ETIOLOGY
This disorder may occur at any period. It is, however, predominantly a disease of early life, beginning most commonly in the second decade. The two sexes are affected equally. The exact etiology is still obscure. Among the predisposing factors the following may be mentioned: (1) trauma, (2) acute infectious diseases, (3) toxic conditions, (4) dental diseases, (5) encephalitis and (6) tuberculosis. While a direct relation could not be demonstrated, these conditions have preceded the onset of facial hemiatrophy. It is interesting to mention that tuberculosis of the apexes of the lung has been found in addition to other pathologic conditions in most cases in which autopsy has been performed. Often the disease may be associated with lesions in the region of the cervical sympathetic system. Paralysis of the brachial plexus is mentioned