We report a case of a 43 year old woman who developed an extensive vulvar kerion caused by Trichophyton menthagrophytes that was initially mistaken for a bacterial infection. The peculiarity of this case lies in the fact that the kerion is rarely located in the vulva and it has not yet been described in the literature. On the contrary, cases have been found in the scalp, beard, eye-brow, etc. We discuss the etiopathogenetic aspects, criteria for differential diagnosis and therapy management of this rare clinical picture.