situs inversus totalis ( sit ) is a rare disorder characterized by the transposition of the thoracic and abdominal organs to the opposite side of the body , in a mirror image of the normal anatomy .
its occurrence makes surgical procedures more challenging owing to the mirror image positioning of organs .
there have been few reports of esophagectomy for esophageal cancer associated with sit in the left decubitus position , , , .
however , there has only been a single case report of this disease treated with thoracoscopic esophagectomy , with the patient in the prone position . here , we present two successful cases of left thoracoscopic esophagectomy in the prone position for esophageal cancer associated with sit .
we also discuss the ideal surgical positioning for thoracoscopic esophagectomy and image training utilizing left - inverted and right - inverted videos of thoracic surgery performed on patients with normal organ positions .
an 82-year - old male patient presented to our hospital following a diagnosis of esophageal cancer during a cancer screening .
an upper gastrointestinal endoscopy revealed a type 2 tumor , and an esophagogram showed a tumor measuring 1.5  cm in diameter in the upper thoracic esophagus . a chest x - ray revealed dextrocardia and a right aortic arch ( fig .
in addition , the thoracic and abdominal visceral positions were mirror images of the normal ( fig .
the patient was clinically diagnosed with t2n1m0 stage iib ( union for international cancer control [ uicc ] , 7th edition ) squamous cell carcinoma of the esophagus . for the administration of general anesthesia ,
the surgeons stood on the left side and a video monitor was placed to the right of the patient in the prone position .
placement of trocars was the same as our standard procedure because it is required to approach both the upper and the lower mediastinum easily .
we performed a thoracoscopic subtotal esophagectomy with radical lymph node dissection using five ports via the left thoracic cavity , with the patient in the prone position under artificial pneumothorax ( fig .
2a ) , followed by hand - assisted laparoscopic gastric mobilization in the supine position . while processing around the gastrosplenic ligament , we performed the operation by inserting the right hand into the peritoneal cavity and using the main instruments with the left hand , unlike the standard procedure .
the forceps of the assistant was inserted into the abdominal cavity from the left side of the abdomen .
the surgical duration and intraoperative blood loss were 661  min and 165  g , respectively ; in total , 49 lymph nodes were resected .
the surgeons underwent image training prior to the surgery using left - inverted and right - inverted thoracoscopic surgical videos of patients with normal anatomy , to recognize the inverted anatomy of this condition ( fig .
the definitive diagnosis was of a pt1bn0m0 p - stage ia ( uicc , 7th edition ) basaloid squamous cell carcinoma of the esophagus .
oral intake resumed on postoperative day 7 , and the patient was discharged on postoperative day 34 . a 66-year - old man presented to our hospital for the treatment of esophageal cancer .
he had undergone endoscopic hemostasis for a bleeding gastric ulcer , and an esophageal type 2 tumor was detected in the middle thoracic esophagus during a follow - up endoscopy .
computed tomography revealed a thick wall around the middle thoracic esophagus and multiple splenic nodules on the right side of his abdominal cavity ( fig .
his duodenum was devoid of a horizontal portion . a larger part of the subsequent colon was not fixed in the retroperitoneum and was present on the right side of the abdominal cavity .
he was clinically diagnosed with t2n1m0 stage iib ( uicc , 7th edition ) squamous cell carcinoma of the esophagus . for general anesthesia ,
we performed a thoracoscopic subtotal esophagectomy with radical lymph node dissection using five ports via the left thoracic cavity , with the patient in the prone position .
a laparoscopic observation of the abdominal cavity identified the mirror image of his abdominal organs and intestinal malrotation .
the surgical duration was 637  min , and intraoperative blood loss was 220  g. the definitive diagnosis was of a pt1bn0m0 p - stage ia ( uicc , 7th edition ) basaloid cell carcinoma of the esophagus .
oral intake resumed on postoperative day 7 , and the patient was discharged on postoperative day 17 .
an 82-year - old male patient presented to our hospital following a diagnosis of esophageal cancer during a cancer screening .
an upper gastrointestinal endoscopy revealed a type 2 tumor , and an esophagogram showed a tumor measuring 1.5  cm in diameter in the upper thoracic esophagus . a chest x - ray revealed dextrocardia and a right aortic arch ( fig .
in addition , the thoracic and abdominal visceral positions were mirror images of the normal ( fig .
the patient was clinically diagnosed with t2n1m0 stage iib ( union for international cancer control [ uicc ] , 7th edition ) squamous cell carcinoma of the esophagus . for the administration of general anesthesia ,
the surgeons stood on the left side and a video monitor was placed to the right of the patient in the prone position .
placement of trocars was the same as our standard procedure because it is required to approach both the upper and the lower mediastinum easily .
we performed a thoracoscopic subtotal esophagectomy with radical lymph node dissection using five ports via the left thoracic cavity , with the patient in the prone position under artificial pneumothorax ( fig .
2a ) , followed by hand - assisted laparoscopic gastric mobilization in the supine position . while processing around the gastrosplenic ligament , we performed the operation by inserting the right hand into the peritoneal cavity and using the main instruments with the left hand , unlike the standard procedure .
the forceps of the assistant was inserted into the abdominal cavity from the left side of the abdomen .
the surgical duration and intraoperative blood loss were 661  min and 165  g , respectively ; in total , 49 lymph nodes were resected .
the surgeons underwent image training prior to the surgery using left - inverted and right - inverted thoracoscopic surgical videos of patients with normal anatomy , to recognize the inverted anatomy of this condition ( fig .
the definitive diagnosis was of a pt1bn0m0 p - stage ia ( uicc , 7th edition ) basaloid squamous cell carcinoma of the esophagus .
oral intake resumed on postoperative day 7 , and the patient was discharged on postoperative day 34 .
a 66-year - old man presented to our hospital for the treatment of esophageal cancer .
he had undergone endoscopic hemostasis for a bleeding gastric ulcer , and an esophageal type 2 tumor was detected in the middle thoracic esophagus during a follow - up endoscopy .
computed tomography revealed a thick wall around the middle thoracic esophagus and multiple splenic nodules on the right side of his abdominal cavity ( fig .
his duodenum was devoid of a horizontal portion . a larger part of the subsequent colon was not fixed in the retroperitoneum and was present on the right side of the abdominal cavity .
he was clinically diagnosed with t2n1m0 stage iib ( uicc , 7th edition ) squamous cell carcinoma of the esophagus . for general anesthesia ,
we performed a thoracoscopic subtotal esophagectomy with radical lymph node dissection using five ports via the left thoracic cavity , with the patient in the prone position .
a laparoscopic observation of the abdominal cavity identified the mirror image of his abdominal organs and intestinal malrotation .
the surgical duration was 637  min , and intraoperative blood loss was 220  g. the definitive diagnosis was of a pt1bn0m0 p - stage ia ( uicc , 7th edition ) basaloid cell carcinoma of the esophagus .
oral intake resumed on postoperative day 7 , and the patient was discharged on postoperative day 17 .
sit is a rare disorder characterized by a complete right  left transposition of the thoracic and abdominal organs compared with their normal positions , .
there are only a few reports discussing esophagectomy in patients with sit , owing to the low incidence of esophageal cancer in patients with this disorder ; sit itself has no pathophysiological significance .
however , approximately 2025% of cases are associated with kartagener s syndrome caused by ciliary dyskinesia .
successful thoracoscopic esophagectomy has been reported in patients with sit accompanied with kartagener s syndrome .
it is very rare for sit and polysplenia syndrome to occur in the same patient .
our first patient had an unremarkable medical history and possessed an acceptable performance status to undergo esophageal surgery , even at his age .
our second patient had multiple splenic nodules on the right side of his abdominal cavity and intestinal malrotation .
polysplenia , a recognized situs ambiguous , should be considered in cases with multiple splenic nodules on the right side of the abdominal cavity .
this syndrome is associated with heterotaxia syndrome , which is defined as the occurrence of multiple splenic nodules and described as a left isomerism , or referring to the duplication of left sided structures , , , .
it has been reported that 5090% of polysplenia syndrome cases are associated with cardiac complications .
some degree of intestinal malrotation is also seen in approximately 70% of the patients with this syndrome , although most cases are asymptomatic .
midgut volvulus associated with intestinal malrotation was previously reported in an adult patient with sit . since the computed tomography image in our second case displayed no cardiac malformation or bilateral bilobed lungs , we diagnosed the patient with intestinal malrotation and polysplenia associated with sit .
recognition  of  sit and its  variation  is  important  in  order  to  avoid  accidental  injuries  intraoperatively .
gastric mobilization via laparotomy should be considered in sit patients associated with other anatomical variations .
a pubmed search using the terms  esophagus  and  situs inversus totalis  from 1976 to june 2016 revealed only 4 cases of thoracoscopic esophagectomy via the left thoracic cavity in the right decubitus position for sit patients , , , .
average blood loss and surgical duration of these cases were 517  min and 260  g , respectively .
esophagectomy in the prone position may improve patient outcome as a less invasive surgical technique , with fewer complications ( e.g. , pneumonia ) and less intraoperative blood loss , .
compared with the lateral position , placement of the patient in the prone position improves visualization and ergonomics during surgeries ; may improve the quality of mobilization and lymphadenectomy ; and appears to contribute to an enhanced learning curve .
these potential advantages of thoracoscopic surgery in the prone position may be maintained in patients with sit . in our cases ,
the surgical duration was almost similar and the amount of bleeding was minimal compared to thoracoscopic surgery in the right decubitus position .
owing to the mirror - image positioning of thoracic and abdominal organs , surgical procedures in patients with sit are often considered more challenging , .
while operating on patients with sit , it is characteristic for a surgeon s right hand to be positioned in the caudal side of the patients in the prone position , which is the opposite of patients with normal anatomy .
it is important to recognize the complex anatomy in these cases , so that surgical planning can be improved .
the surgeons in this study performed esophagectomy in patients with sit for the first time .
although we have encountered several similar cases before , the surgeons in this study have not been able to perform in the previous cases . in rare cases , such as those of patients with
sit , the selection of easier and more practical surgical methods and utilization of prior image training with right - inverted and left - inverted videos will be helpful to ensure surgical safety . this work has been reported in line with the scare criteria .
thoracoscopic surgical treatment for esophageal cancer associated with sit in the prone position can be performed safely , similar to the manner performed for thoracoscopic surgery in the right decubitus position , or surgery via an open thoracothomy .
left - inverted and right - inverted thoracoscopic surgical videos of patients with normal anatomy were useful as preoperative image training .
written informed consent were obtained from the patients for publication of this case report and any accompanying images .
a copy of the written consent is available for review by the editor - in - chief of this journal .
nakano t is the first author of this article ; nakano t , kamei t , sakurai t , taniyama y , sato c , and ohuchi n were attending doctors and performed clinical treatment including surgical operation ; onodera y and ujiie n constructed the imaging and prepared the figures ; all authors have read and approved the final manuscript .
toru nakano and noriaki ohuchi are accept full responsibility for the work and had controlled the decision to publish .
 introductionsitus inversus totalis ( sit ) is a rare congenital condition characterized by a complete transposition of thoracic and abdominal organs . here 
 , we present two successful cases of left thoracoscopic esophagectomy in the prone position for sit - associated esophageal cancer.presentation of caseour first case was of an 82-year - old man who underwent a left thoracoscopic esophagectomy in the prone position , followed by hand - assisted laparoscopic gastric mobilization . surgical duration and 
 blood loss were 661  min and 165  g , respectively . 
 his postoperative course was uneventful . 
 the second case was of a 66-year - old man who underwent a left thoracoscopic esophagectomy in the prone position , followed by gastric mobilization via laparotomy owing to a concomitant intestinal malrotation and polysplenia . 
 surgical duration and blood loss were 637  min and 220  g , respectively . 
 we trained for the surgical procedures preoperatively using left - inverted and right - inverted thoracoscopic surgical videos of patients with normal anatomy.discussionsurgical procedures in sit patients are challenging owing to their mirrored anatomy . 
 recognition  of their  variations  is  thus important to  avoid  intraoperative accidental injuries . left - inverted and right - inverted thoracoscopic surgical videos of patients with normal anatomy were found to be useful for image training prior to the actual surgery.conclusionthoracoscopic surgical treatment for esophageal cancer associated with sit in the prone position can be performed safely , similar to the manner performed for thoracoscopic surgery in the right decubitus position , or surgery via an open thoracotomy . 
 gastric mobilization via laparotomy should be considered in patients associated other anatomic variations . 
Introduction
Case presentation
Case 1
Case 2
Discussion
Conclusion
Conflicts of interest
Consent for publication
Funding
Ethical approval
Authors contributions
Guarantor