Progressive hemifacial atrophy is also known as Parry-Romberg syndrome. It is a progressive unilateral facial tissue nutritional disorder. In a few cases, the lesions involve the limbs or the trunk, which is called progressive hemifacial atrophy. Its clinical features are the chronic progressive atrophy of subcutaneous fat and connective tissue on one side of the face. The muscle fibers are not affected. In severe cases, the cartilage and bones are invaded. Most scholars believe that this disease is related to sympathetic nerve dysfunction. Sympathetic nerve damage caused by various reasons causes neurotrophic disorders of facial tissue, which eventually leads to facial tissue atrophy. Other theories involve local or systemic infection, injury, trigeminal neuritis, connective tissue disease, genetic degeneration, etc. The speed of disease progression is uncertain. Most cases tend to improve after several years to more than ten years, but the associated epilepsy may continue.