Choriocarcinoma Presenting as a Metastatic Pancreatic Mass: a Cytopathologic Diagnostic Challenge

Abstract

Abstract Introduction/Objective Choriocarcinoma is a malignant tumor of trophoblasts, with gestational choriocarcinoma as the most common type. It commonly presents with vaginal bleeding and uterine mass; occasionally, hemorrhage due to metastatic disease to the lung, liver, brain, and gastrointestinal tract may be the first presentation. We describe an unusual case of metastatic gestational choriocarcinoma presenting as a pancreatic head mass mimicking a pancreatic neuroendocrine tumor (PanNET). The concern for choriocarcinoma was raised by fine-needle aspiration (FNA) cytology. Methods/Case Report A 32-year-old woman, 16 months status-post caesarian delivery of healthy twins, presented with progressive right upper quadrant and epigastric pain, nausea, and marked elevation of Beta-hCG, lipase, ALT, and AST levels. Abdominal CT revealed a hypoenhancing 2.6 cm pancreatic head mass and multiple liver nodules, suggestive of PanNET with liver metastasis. Endoscopic ultrasound and FNA of the pancreatic mass revealed a poorly differentiated tumor composed of bizarre large malignant cells with marked cytologic atypia, focal spindle cell change, and rare multinucleated cells. By immunohistochemistry, the tumor cells were positive for pancytokeratin, CAM5.2, and CD56 (focally), while negative for synaptophysin, chromogranin, inhibin, P63 and P40. While pancreatic adenocarcinoma and PanNET couldn’t be completely ruled out, metastatic choriocarcinoma was also considered; however, inconclusive immunostaining warranted a tissue biopsy. Follow-up liver biopsy and FNA showed that tumor cells were positive for Beta-hCG and negative for SALL4, placenta lactogen, HepPar1, and TTF1 immunostains, compatible with choriocarcinoma. Molecular analysis using short tandem repeat supported a gestational origin of the tumor. The patient underwent chemotherapy with marked improvement in her status and beta-hCG levels. Results (if a Case Study enter NA) NA Conclusion Although highly aggressive, gestational choriocarcinomas show good treatment response, necessitating accurate diagnosis in cases of an atypical presentation. Choriocarcinoma presenting as metastatic pancreatic mass is extremely rare and poses a diagnostic cytopathologic and radiologic challenge that requires comprehensive correlation with clinical and laboratory data.