Vulvar endometriosis. A clinical, histological and dermoscopic riddle

Endometriosis is characterized by the presence of functional endometrial tissue in ectopic sites such as ovaries, fallopian tubes and pelvic peritoneum. Rare extra-pelvic localizations are possible, including skin involvement. Cutaneous endometriosis is divided into primary and secondary endometriosis. The latter occurs on scar tissue, mostly following caesarean section. Endometriosis may present cyclical pain, bleeding and swelling depending on the menstrual cycle even though most cases are asymptomatic. The vulvar case described confirms the remarkable variability and unspecificity of dermoscopic patterns of endometriosis. Biopsy with staining for ER, PR and CD10 is mandatory for diagnosing and ruling out malignant conditions.