Bilateral Osseous Metaplasia of the Ovary in Association with Endometrioma: A Rare Case Report

Osseous metaplasia of nonteratomous ovarian cyst is extremely rare, with 33 cases having been reported in the literature till 2020. Research is needed to fully understand the pathogenesis and clinical implications of this condition. Hence, we report this case of a 43-year-old woman with left-sided ovarian endometrioma and osseous metaplasia of both ovaries. A 43-year-old primipara presented with heavy menstrual bleeding and dysmenorrhea of 4 years duration. An ultrasound performed 5 months back showed bilateral ovarian endometriomas, and she had been treated medically. Upon presentation to us, an ultrasound revealed an adenomyotic uterus, with right ovary measuring 3.3 cm × 3.8 cm and left ovary measuring 2.5 cm × 2.8 cm. She was started on tablet dienogest once a day. A repeat ultrasound 3 months later revealed enlarged and calcified right ovary measuring 6 cm × 5 cm and left ovary measuring 5 cm × 4 cm. Her cancer antigen 125 was 21.8 U/mL She denied for an MRI pelvis. Total abdominal hysterectomy and bilateral adnexectomy were performed. Histopathology of the right ovary showed ovarian parenchyma along with areas of extensive osseous metaplasia with calcifications. Sections from the left ovary showed ovarian parenchyma with an endometriotic cyst and moderate to dense inflammation with multiple foci of osseous metaplasia with calcifications. To conclude, osseous metaplasia of the ovary is rare. Our case was associated with benign ovarian endometrioma. The exact etiology of osseous metaplasia of the ovary is not known. We report this case to shed more light on the subject.