6694 A Case of an Extraneous Organ: A Uterus Found in a Genotypic and Phenotypic Male

Abstract Disclosure: R.A. Zielinski: None. S. Shteyman: None. A.G. Samat: None. Background: Persistent Mullerian Duct Syndrome (PMDS) is a rare entity that occurs when a phenotypic male is found to have female reproductive organs. In our case we describe an XY male who was found to have an abdominal mass consistent with a uterus on pathology. Clinical Case: Our patient is a 58-year-old male with hypertension, obesity, and obstructive sleep apnea who presented to the ED with 3 weeks of left upper quadrant pain. Abdominal CT showed two homogeneous enhancing oval lesions in the pelvis superior to the urinary bladder; 8.3 x 4.6 cm on the right and 3.6 x 3 cm on the left. Exploratory laparotomy was performed, and intraoperatively the mass was firm with a left satellite lesion and two fibrous bands that appeared similar in structure to round ligaments. Microscopically the tissue contained mullerian-type epithelium and smooth muscle with cystic degeneration. It was CK7 positive, estrogen receptor variable positive, and CK20 negative. Genetic testing confirmed the patient’s karyotype to be XY without genetic mosaicism. Our patient had two children spontaneously, regular spontaneous erections, and occasional hot flashes. Physical exam revealed an obese male (BMI 51) with bilateral gynecomastia and normal testicular size. He had no history of intra-abdominal or undescended testes requiring surgery. Labs showed increased total estrogen (283.7 pg/mL, n 60-190 pg/mL) and estradiol (39 pg/mL, n <= 29 pg/mL), decreased total testosterone (86 ng/dL, n 250-1,100 ng/dL), and normal free testosterone when corrected for SHBG (140 ng/dL, n 110-574 ng/dL). Testicular ultrasound was unrevealing. 3 years postoperatively his estradiol level normalized (34 pg/mL) and his total testosterone improved from 86 ng/dL to 223 ng/dL after losing 40 pounds on semaglutide. Discussion and Conclusion: Although the exact incidence of PMDS is unknown, it is a rare phenomenon. Only 200 cases between 1964 and 2000 and 34 cases between 2013 and 2017 have been reported. Mullerian ducts are embryologic structures present in both XY and XX fetuses until week 8 of life, when XY fetuses produce anti-mullerian hormone (AMH). In PMDS, the XY fetus either fails to produce AMH, or there is a defect in the AMH receptors, leading to the persistence of mullerian ducts. These ducts can then differentiate into a uterus, fallopian tubes, and/or the upper vagina. Our patient is a genotypical and phenotypical male with a uterus-like organ. The mild elevation in his estrogen level is likely secondary to his obesity. The estrogen could have increased the size of the uterus, causing the patient’s initial symptoms of abdominal pain which prompted his presentation to the hospital. References: Picard, Jean-Yves, et al. “The Persistent Müllerian Duct Syndrome: An Update Based UponPersonal Experience of 157 Cases.” Sexual Development, vol. 11, no. 3, 2017, pp. 109-125, https://doi.org/10.1159/000475516. Presentation: 6/3/2024