White sponge nevus (WSN) is an autosomal dominant condition of the oral mucosa (the mucous membrane lining of the mouth). It is caused by a mutations in certain genes coding for keratin, which causes a defect in the normal process of keratinization of the mucosa. This results in lesions which are thick, white and velvety on the inside of the cheeks within the mouth. Usually, these lesions are present from birth or develop during childhood. The condition is entirely harmless, and no treatment is required. Signs and symptoms
It presents itself in the mouth, most frequently as a thick, bilateral, symmetrical white plaques with a spongy, corrugated or velvety texture. Most usually, the lesions are on the buccal mucosa, but sometimes on the labial mucosa, alveolar ridge, floor of the mouth, ventral surface of the tongue or soft palate. The gingival margin and dorsum of the tongue are almost never affected. Less commonly, sites outside the mouth are affected, including the nasal, esophageal, laryngeal, anal and genital mucosae. It usually is present from birth, or develops during childhood. Rarely, the lesions may develop during adolescence. Apart from the appearance of the affected areas, there are usually no other signs or symptoms. Pathophysiology
WSN is caused by a mutation of the keratin 4 or keratin 13 genes, located respectively at human chromosomes 12q13 and 17q21-q22. The condition is inherited in an autosomal dominant manner.
Before the 17th century, the joint pain which was thought to be caused by viscous humours seeping into the joints was always referred to as gout, a word adopted in Middle English from Old French gote "a drop; the gout, rheumatism", not to be confused with the present day specific term referring to excess of uric acid.The English term rheumatism in the current sense has been in use since the late 17th century, as it was believed that chronic joint pain was caused by excessive flow of rheum which means bodily fluids into a joint. See also
Corbetts electrostatic machine

References
Further reading
Callan, Margaret (2011). The Rheumatology Handbook. 15th World Congress of Pain Clinicians, (WSPC 2012) (Illustrated ed.). World Scientific. ISBN 978-1-84816-320-1. External links
American College of Rheumatology
National Institute of Arthritis and Musculoskeletal and Skin Diseases - US National Institute of Arthritis and Musculoskeletal and Skin Diseases