Primary endodermal sinus tumor originating from the sacral ligament: a case report and review of the literature

BACKGROUND: Endodermal sinus tumor (EST) is a malignant tumor originating from the ovary or testis. In most case, ultrasound examination shows ovarian mass. But there is a special kind of extra-gonadal endodermal sinus tumor, which occur in organs other than gonads with insidious onset. Here we reported a case of endodermal sinus tumor, which originated from the sacral ligament presenting as an acute lower abdominal pain. CASE PRESENTATION: A 14-year-old girl was admitted to the hospital because of acute lower abdominal pain. The ultrasound showed a mass with 72 mm × 64 mm × 50 mm in Douglas, and there was no abnormality in bilateral ovaries and fallopian tubes. Laparoscopic exploration showed a large amount of blood clots in the pelvic cavity. After removal of the blood, we found rotten fish-like tissue in the left sacral ligament, rapid pathology suggested endodermal sinus tumor. After the operation, we retrospectively examined the value of alpha-fetoprotein (AFP), which was found to be elevated, and post-operative paraffin pathology confirmed the diagnosis. After four cycles of BEP chemotherapy, exploratory laparotomy was performed to remove the visible lesion, but postoperative pathology showed no abnormality. At the one-year follow-up, the patient remained recurrence-free. CONCLUSION: Extra-gonadal germ cell tumors are rarely reported. When young teenagers complain of acute lower abdominal pain with elevated AFP, but there was no lesion in bilateral ovaries and fallopian tubes, we must think about the possibility of endodermal sinus tumors. Accurate diagnosis facilitates complete resection of lesions and improves patient’s outcomes.