Yolk Sac Tumor of the Ovary with Polyvesicular-Vitelline Pattern: Case Report of an Uncommon Tumor and a Brief Review of the Literature

Ovarian yolk sac tumors (YSTs) are rare malignant germ cell tumors (GCTs) that can present with nonspecific abdominal symptoms and pose a diagnostic challenge, particularly when classic histologic features are absent. We report a case of a 23-year-old female with no clinically significant medical history who presented with worsening abdominal distension and a palpable mass for four weeks. Associated symptoms included 11-pound unintentional weight loss, early satiety, and pelvic pain. Treatment with analgesics resulted in no improvement. Rapid enlargement and worsening of her abdominal distention warranted an urgent gynecological referral. Transvaginal ultrasonography revealed a large, complex adnexal mass measuring 18 x 15 x 14 centimeters. Computed tomography (CT) demonstrated a solid mass without calcifications, mild omental thickening, and mild ascites. Laboratory studies showed markedly elevated Alpha-fetoprotein (AFP) levels and mildly elevated beta-hCG and Lactate dehydrogenase (LDH). Considering the imaging and labs, a malignant germ cell tumor was suspected. The patient underwent a right unilateral salpingo-oophorectomy. Pathological examination revealed a unique polyvesicular-vitelline appearance, including multiple vesicles and cysts with no evidence of Schiller-Duval bodies. Immunohistochemistry (IHC) was positive for AFP and glypican-3, with cytoplasmic staining, confirming the diagnosis of yolk sac tumor. The patient completed adjuvant chemotherapy and underwent serial AFP monitoring. Three months after initial treatment, AFP was undetectable, and CT was unremarkable. The patient remained in complete remission three years after initial treatment. This case details a rare germ cell tumor with an uncommon histologic pattern, lacking the disease's classic hallmark. This case emphasizes the importance of keeping a broad differential diagnosis in patients with progressive abdominal complaints.