Erythroplakia is a clinical term to describe any erythematous (red) area on a mucous membrane,[2] that cannot be attributed to any other pathology.

[3]: 805 The term erythroplasia was coined by Louis Queyrat to describe a precancerous red lesion of the penis.

Depending upon the context, this term may refer specifically to carcinoma in situ of the glans penis or vulva appearing as a red patch, or may be used as a synonym of erythroplasia on other mucous membrane or transitional sites.

[2][7] Although often the terms erythroplasia and erythroplakia are used synonymously, some sources distinguish them, stating that the latter is macular (flat) while the former is papular (bumpy).

Microscopically, the tissue exhibits severe epithelial dysplasia, carcinoma-in-situ, or invasive squamous cell carcinoma in 90% of cases.

Since the underlying vascular structures are less hidden by tissue, erythroplakia appears red when viewed in a clinical setting.

In 1911, French dermatologist Louis Queyrat described a sharply defined, bright red, glistening velvety precancerous lesion of the glans penis.