A 23-year-old woman, gravida 1 para 1, comes to the office due to pain in the right lower quadrant for 2 months. The pain is unrelieved by acetaminophen and worsens with physical activity. Menses are regular and occur every 28 days. The patient has a history of severe dysmenorrhea and takes oral contraceptive pills daily. Two years ago, she was treated for pelvic inflammatory disease. She has no chronic medical conditions and has had no surgeries. The patient smokes a pack of cigarettes a day but does not use alcohol or illicit drugs. Temperature is 36.7 C (98.1 F), blood pressure is 126/74 mm Hg, and pulse is 87/min. BMI is 36 kg/m². The abdomen is soft and nontender. Pelvic examination reveals right adnexal fullness but is limited by habitus. Pregnancy test is negative. Pelvic ultrasonography shows a 4-cm ovarian mass. The patient undergoes laparoscopic ovarian cystectomy, and a photograph of the cyst is shown in the exhibit. Which of the following is the most likely diagnosis?

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11ec25c8_d9d2_a408_bc81_0bb0af269dc0_MD0003_00 This patient has a mature cystic teratoma (ie, dermoid cyst), a benign ovarian germ cell tumor that typically occurs in young women. Patients with teratomas are usually asymptomatic and may be diagnosed incidentally (eg, adnexal fullness) on pelvic examination. Because teratomas have variable mass densities, they are prone to ovarian torsion because they have an intrinsically unstable suspension across the infundibulopelvic ligaments, which contain the ovarian vessels. As a result, sudden movement may cause intermittent ovarian vessel occlusion, leading to intermittent ovarian torsion, as seen in this patient's pelvic pain that worsens with physical activity. Teratomas typically appear as adnexal masses with multiple calcifications on ultrasound but are definitively diagnosed after ovarian cystectomy, which preserves fertility and reduces the risk of torsion and malignant transformation. Teratomas have a gross appearance consistent with the 3 germ cell layers, including ectodermal elements such as thick, yellow sebaceous fluid and hair (arrow); mesodermal (eg, cartilage, adipose tissue) and endodermal (eg, thyroid) components may also be seen. (Choice A) A corpus luteum cyst is a physiologic remnant of a ruptured follicle after ovulation; it has a yellow appearance from granulosa cell lipids and pigment. This diagnosis is unlikely because this patient is on oral contraceptives (ie, anovulatory) and corpus luteum cysts do not contain hair. (Choice B) Pelvic inflammatory disease and tobacco use are risk factors for ectopic pregnancy, which grossly appears as fetal tissue implanted within a dilated, edematous fallopian tube. This patient has a negative pregnancy test. ectopic pregnancy (Choice C) Endometriomas may cause severe dysmenorrhea and adnexal fullness; however, this diagnosis is unlikely because endometriomas are a collection of old blood that creates a "chocolate cyst" appearance. "chocolate cyst" (Choice E) Mucinous cystadenomas are benign surface epithelial ovarian masses that appear as thin-walled loculations of mucinous fluid; there is no associated hair. mucinous fluid (Choices F) Patients with pelvic inflammatory disease are at risk for tubo-ovarian abscess; however, these abscesses are typically filled with purulent material, which is not seen in this patient. (Choice G) Yolk sac tumors are malignant germ cell tumors with gray-yellow, necrotic, and hemorrhagic areas on a gross specimen; there is no associated hair. Educational objective: Mature cystic teratomas are benign ovarian germ cell tumors that contain all 3 germ cell layers and can have sebaceous fluid and hair on gross appearance. References: Laparoscopic treatment of ovarian dermoid cysts is a safe procedure. (http://www.ncbi.nlm.nih.gov/pubmed/22117832) Ovarian teratoma in routine biopsy material during a five-year period. (http://www.ncbi.nlm.nih.gov/pubmed/28394114) Spectrums and outcomes of adnexal torsion at different ages. (http://www.ncbi.nlm.nih.gov/pubmed/28480536)

A 23-Year-Old Woman, Gravida 1 Para 1, Comes to the Office