Vulvar keratoacanthoma.

A keratoacanthoma of the vulva in a 33-year-old woman is described. The patient presented with a rapidly growing exophytic lesion of 1 cm in diameter over the clitoris that had been present for a couple of months. An excisional biopsy was performed. Pathologic examination of the exophytic nodule showed squamous proliferation with a characteristic central keratin- filled crater. There were pushing margins. High power microscopy showed squamous cells of cytologically bland appearance with glassy cytoplasm. There were few mitotic figures. Less than 10% Ki-67-positive staining nuclei were seen. There was no p53 oncoprotein overexpression. Keratoacanthoma of the vulva is rare with only five cases having been reviewed in the English literature since 1985. Keratoacanthomas are rapidly growing crateriform lesions on the sun-exposed skin of the elderly. Because of its rarity in the vulva, the lesion can be misinterpreted as a malignant lesion such as squamous cell carcinoma. Awareness of vulvar occurrence of keratoacanthoma and its characteristic histopathologic features will help avoid misdiagnosis of a squamous cell carcinoma leading to radical surgery.