Primary Gastric Choriocarcinoma Presenting as a Pregnancy of Unknown Location

Pregnancy of unknown location presents a diagnostic challenge, in rare occasions leading to the diagnosis of malignancy. We describe a case of β-hCG-secreting nongestational primary gastric choriocarcinoma presenting as a pregnancy of unknown location.

A 37-year-old woman, gravida 4 para 3013, presented with several days of vaginal bleeding and rising β-hCG level without ultrasound localization of pregnancy. The diagnosis of pregnancy of unknown location was made and methotrexate administered at a β-hCG level of 7,779 milli-international units/mL. A 40% decrease in β-hCG level was noted between days 4 and 7. One week later, an inappropriate β-hCG level rise to 10,937 milli-international units/mL was noted, prompting a second dose of methotrexate and computed tomography imaging, leading to the discovery of gastric and liver lesions. Pathology from gastric biopsies revealed nongestational choriocarcinoma. The patient was treated with chemotherapy, with death from cardiac arrest 7 months after diagnosis.

Malignancies that can secrete β-hCG include gestational trophoblastic disease, gonadal and extragonadal germ cell tumors, and malignancies with choriocarcinoma differentiation. Although ectopic pregnancy compromises approximately 2% of first-trimester pregnancy, gestational trophoblastic neoplasia and gestational choriocarcinoma can be seen in 1 of 1,500 and 1 of 20,000 pregnancies, respectively. When β-hCG levels do not fall appropriately in women undergoing medical management for pregnancy of unknown location, ectopic β-hCG secretion by a malignancy must be considered.