Dermoid cysts are usually asymptomatic until complications occur. Spontaneous rupture of a dermoid into an adjacent organ is a rare complication and no such case has been reported in the Philippines.

A 24-year-old primipara consulted for pilimiction. Three years earlier, she had recurrent urinary tract infection and was diagnosed to have a dermoid cyst. Left untreated, the cyst grew in size and urinary symptoms worsened. Ultrasound, CT scan and subsequent laparotomy revealed that the dermoid cyst has penetrated the bladder wall resulting to fistula formation between the dermoid and the urinary bladder. Hair and sebum were seen inside the bladder. A left salpingo-oophorectomy and partial cystectomy of the urinary bladder were done.

The first locally documented case of an ovarian dermoid cyst with fistula to the bladder is presented. A review of literature is made, the predisposing factors, possible cause, diagnosis and management are discussed.