Primary<unk>  may be classified as either familial or sporadic, with the familial form inherited in an autosomal dominant manner. Both of these may be further classified as either juvenile or adult onset. The juvenile onset form occurs prior to age 20 and frequently prior to age 10. While the genetic cause of the juvenile and sporadic adult onset forms is often known, this is not the case for the adult onset familial form. In rural areas of southern China, outbreaks of<unk>  have occurred during winter and spring at 3-5 year intervals among secondary school students. This epidemic form of<unk>  has been viewed as a different form of non-inherited primary<unk>  and affects mainly teenage girls in middle schools. The disease is characterized by burning pain in the toes and soles of the feet, accompanied by foot redness, congestion, and edema; a few patients may have fever, palpitations, headache, and joint pain. In the 1987 epidemic in Hubei, 60.6% of patients had a common cold before the onset of<unk>  and 91.2% had pharyngitis. Billing codes systems and other systems<unk>  can be found in several billing codes systems and other systems.<unk>  is generally classified as a disease of the circulatory system, falling under the class of other peripheral vascular disease, as the following two billing code systems will show: * ICD-9-CM According to the ICD-9-CM database (International Classification of Diseases, Ninth Revision, Clinical Modification),<unk>  is listed under Diseases of the Circulatory System and is identified by number 443.82. * ICD-10-CM According to the ICD-10-CM database (International Classification of Diseases, Tenth Revision, Clinical Modification),<unk>  is listed under Diseases of the circulatory system and is identified by I73.81. * Mesh According to the MESH database (Medical Subject Headings),<unk>  is classified under the unique ID number of D004916. * OMIM According to the OMIM database (NCBI - Online Mendelian Inheritance in Man), Primary<unk>  is listed under the number: 133020.
Erythromelalgia
Coxalgia
Pathergy
Chromesthesia
Pressure urticaria
Heat urticaria
Onycholysis
Allodynia