White Sponge Nevus.

White Sponge Nevus

White sponge Nevus (WSN) also known as Cannon´s Disease, Hereditary Leukokeratosis, is an uncommon autosomal-dominant condition with variable expressivity and a high degree of penetrance that appears to be due to Keratin 4 and or 13 point mutations. Gender predisposition does not exist and the majority of described cases refer to the white race. It affects oral mucosa bilaterally, and no special treatment is required. WSN present as an asymptomatic, white lesion (plaque) that may affect several mucosal sites. Lesions tend to be thickened and have a spongy consistency. The presentation intraorally is almost always bilateral, symmetric and usually appears early in life, typically before puberty. The gingival margin and dorsum of the tongue are almost never affected. The conjunctival mucosa is usually spared, but mucosa of the esophagus, anus, vulva, and vagina may be affected. Histopathology. The hallmark microscopic feature of this disease is an extensive and often marked intracellular edema of the superficial epithelial cells, predominantly within the spinous layer. The epithelium is greatly thickened, with marked acanthosis. There is parakeratosis, and spongiosis. Perinuclear eosinophilic condensation of cytoplasm is characteristic of prickle cell in WSN. The nuclei are typically pyknotic and the cells may mimic the koilocytes of viral infections. The basement membrane is intact, and the rete pegs are long and thin. The connective tissue generally, has no, or very slight, inflammation. Differential diagnosis. 1- Oral changes in hereditary benign intraepithelial Dyskeratosis or Witkop´s Disease are identical to those of white sponge nevus, but the former disease shows unique microscopic cells and clinically evident ocular changes. Others clinically similar white macules or plaques may also be seen in the mouths of persons with Pachyonychia congenital and Dyskeratosis congenital. 2-Occasional lesions are less thickened and reveal a semitransparent appearance. Lesions are usually well demarcated from the surrounding normal mucosa, as opposed to the poor demarcation of Leukoedema and smokeless tobacco Keratosis. 3-Chronic cheek bite Keratosis. 4- Lichen planus and Lupus erythematous.

REFERENCES. 1-Jorgenson RJ, Levin LS. White sponge nevus. Arch Dermatol 1981; 117:73-76. 2-Rugg EL, et al. A mutation in the mucosal keratin K4 is associated with oral white sponge nevus. Nat Genet 1995; 11:450-452. 3-Chao SC, Tsai YM, Yang MH, Lee JY. A novel mutation in the keratin 4 gene causing white sponge naevus. Br J Dermatol. 2003;148(6):1125-8. 4-Lucchese A, Favia G. White sponge naevus with minimal clinical and histological changes: report of three cases. J Oral Pathol Med. 2006;35(5):317-9.