RESUMO
Nodular histiocytic/mesothelial hyperplasia (NHMH) is a very rare condition. It is generally thought to be associated with repeated mechanical or chemical stimulation. This study reported NHMH with papillary growth pattern in the ovary following high-intensity focused ultrasound (HIFU) treatment for uterine leiomyoma and adenomyosis. A 48-year-old female, who had a history of undergoing HIFU treatment 7 times for adenomyosis and leiomyoma of the uterus 6 months ago, was referred to the hospital. After the hysterectomy and right salpingo-oophorectomy, the patient was confirmedly diagnosed with nodular histiocytic and mesothelial hyperplasia with the papillary growth pattern of the right ovary. This benign reactive inflammatory lesion of the mesothelium mimicking malignancy must be kept in mind to avoid unnecessary treatment.