non - gestational choriocarcinomas are rarely seen outside the gonads , with the mediastinum being the main site for these non - gestational extragonadal choriocarcinomas .
there is no consensus regarding the use of systemic chemotherapy [ 1 , 2 ] .
studies undertaken on treatment for the metastatic disease indicate that chemotherapies based on cisplatin , methotrexate or 5-fu are not efficient [ 1 , 2 ] .
there is no metastatic gastric choriocarcinoma case in the literature that showed a complete response to chemotherapy .
herein , we present a human epidermal growth factor receptor-2 ( her2)-positive gastric adenocarcinoma case which has a choriocarcinomatous component and showed a complete response to trastuzumab chemotherapy .
a 57-year - old female patient was admitted for weakness , lack of appetite , weight loss and abdominal pain .
the patient did not have a disease history and had not been under any medical treatment . on physical examination the mucosa was pale and no abdominal mass was detected .
laboratory analysis revealed hypochromic , microcytic anemia ( hb : 9 g / dl ) .
upper endoscopic examination revealed a mass in the gastric antrum , which was reported to be adenocarcinoma by biopsy .
postoperative pathological analysis revealed the presence of adenocarcinoma associated with choriocarcinoma ; histologically , intestinal type adenocarcinoma composed of columnar gland - forming cells interspersed with cytotrophoblast and syncytiotrophoblast cells staining positive for beta - human chorionic gonadotropin ( -hcg ) on immunohistochemistry ( fig . 1 , fig .
2 ) . the patient 's serum -hcg level , which was measured in light of these pathological findings , was 22.823 iu / ml .
multiple liver metastases and a metastasis in the right iliac bone were detected on pet - ct imaging for tumor staging .
the patient was given two cycles of dcf ( docetaxel , cisplatin , 5-fu ) as treatment .
however , the patient did not tolerate the treatment due to the development of grade 3 diarrhea and mucositis .
therefore , the dcf treatment was replaced with a combination of docetaxel , carboplatin and trastuzumab .
-hcg level had decreased to 6 iu / ml , and pet - ct scans showed a complete response ( fig .
the patient is currently on the 24th month of the treatment and the complete response is still ongoing .
the most widely accepted theory holds that the trophoblastic cells in gastric choriocarcinoma develop from dedifferentiation of a poorly differentiated adenocarcinoma .
in fact , cytogenetic studies show that gastric choriocarcinoma genetically possesses characteristics of both adenocarcinoma and choriocarcinoma . in our patient choriocarcinoma accompanied adenocarcinoma and
therefore , pathological analysis of the biopsy sample by an experienced pathologist increases the chance of establishing a diagnosis .
consecutive measurements of serum -hcg levels in the postoperative or post - chemotherapy periods are valuable for the assessment of treatment response or recurrence of the disease .
the most common metastasis sites are lymph nodes ( 87% ) , followed by liver ( 45% ) , peritoneum ( 23% ) and lungs ( 8% ) .
gastric choriocarcinomas are highly malignant and most patients die within a year of diagnosis . although more than 140 gastric choriocarcinoma cases have been reported in the literature until now , there is no consensus concerning the treatment strategy for the disease .
in addition to surgery and radiotherapy , various cytotoxic drugs have been used for the treatment . however , contrary to gestational choriocarcinomas , all chemotherapy regimens were found to be ineffective in metastatic gastric choriocarcinoma . a choriocarcinoma case who received trastuzumab therapy was not found in the literature . in gastric cancers
however , her2-positive gastric cancer patients benefit significantly from trastuzumab therapy . when compared with normal placenta or her2 expression
furthermore , choriocarcinoma components showed significantly higher her2/neu expression compared to other histological subtypes in testicular germ cell tumors ( p = 0.0095 ) .
these data suggest that cerbb2 oncoprotein may be important in the pathogenesis of choriocarcinoma , but there is no information concerning the use of trastuzumab for the treatment .
overexpression was present in our case and complete response was obtained after adding trastuzumab to the treatment .
in order to establish a preoperative diagnosis for gastric choriocarcinoma , it is important to bear this tumor in mind and adopt a skeptical approach .
most patients have metastases at the time of establishing a diagnosis and the tumor has a significantly poor prognosis .
determining her2 expression in every patient and using trastuzumab treatment in positive cases may lead to positive therapeutic outcomes , as in our case .
 gastric choriocarcinoma is a rare neoplasm and usually accompanies gastric adenocarcinoma . 
 the prognosis is poor due to the aggressive course of the disease . 
 a 57-year - old female patient with weight loss and abdominal pain was examined . 
 the patient was operated following the examination , and pathological analysis revealed the presence of a gastric adenocarcinoma associated with choriocarcinoma . 
 immunohistochemical analysis showed a positive reaction with antibodies to beta - human chorionic gonadotropin and overexpression of the cerbb2 proto - oncogene . 
 staging revealed multiple metastases in the liver . 
 a complete response was obtained with a combination of trastuzumab and chemotherapy . 
 the diagnosis of gastric choriocarcinomas without pathological examination is difficult due to their rare occurrence . 
 a complete response can be obtained with trastuzumab in the treatment of cases with overexpression of the cerbb2 protein . 
Introduction
Case Report
Discussion
Conclusion
Disclosure Statement