In PART 1, various rare types of hernias around the inguinal region and internal hernias of the abdomen were reviewed. In PART 2, a variety of rare abdominal wall and diaphragmatic hernias are considered. Several studies have indicated that each rare hernia may have typical images, and computed tomography is the most valuable tool for correct diagnosis. Laparoscopic and thoracoscopic surgeries have been frequently performed for the treatment of hernia repair, and a decision of whether mesh repair of hernias can be applied is clinically important. Every clinical surgeon must have knowledge of these rare hernias and the ability to flexibly deal with such rare situations. In the final section of this paper, rare cases of postoperative complications are treated as important issues. Since hernias are non-malignant, care should be taken to reduce postoperative pain and hernia recurrence while maintaining an excellent quality of life.

Here, we report an extremely rare case of a well-differentiated liposarcoma in a lipoma originating in the breast. A 70-year-old woman was referred to the outpatient breast clinic because of the detailed examination of a 5 cm large subcutaneous mass in the lower area of her left breast. Since differential diagnosis between lipoma and well-differentiated liposarcoma could not be accurately achieved through tissue biopsy, the mass was widely excised. The result showed reddish-brown tumor of 2 cm with irregular borders within the lipoma in the sectioned specimen, and a pathological diagnosis of well-differentiated liposarcoma was concluded by histological examination including adequate immunohistochemistry (IHC).

Preoperative diagnosis of a well-differentiated liposarcoma originating within a lipoma is very difficult. For lipomas ranging in diameter between 5 cm and 10 cm, wide excision and histologic examination, including IHC of the resected specimen, is another treatment option.

An adenomyoepithelioma is a benign tumor in which both glandular epithelial cells and myoepithelial cells proliferate. In rare instances, a malignant adenomyoepithelioma, in which either or both cells become malignant, may develop. In this study, we present two such cases of malignant breast adenomyoepithelioma treated with neoadjuvant chemotherapy and a relevant literature review. Case 1 was of a 32-year-old woman who presented with the chief complaint of a mass exceeding 5 cm in the left breast. A needle biopsy revealed an invasive ductal carcinoma, and she was diagnosed with a T3N1M0 stage IIIA for which neoadjuvant chemotherapy was administered. Following mastectomy and axillary lymph node dissection, postoperative histopathological examination revealed a malignant adenomyoepithelioma, requiring further chemotherapy and hormone treatment. The patient was healed and remains alive and without recurrence 6 years and 4 months after the surgery. Case 2 was of a 73-year-old woman in whom a thorough examination revealed a 15-mm mass in the left breast. A needle biopsy indicated an invasive, triple negative, ductal carcinoma. Neoadjuvant chemotherapy was performed, as well as a mastectomy and sentinel lymph node biopsy. Here too, a postoperative histopathological examination revealed a malignant adenomyoepithelioma. In this case, capecitabine was administered postoperatively, and the patient remains alive and without recurrence 1 year after the surgery.

Apart from Paget's disease, breast cancer is believed to originate from the terminal ductal lobular unit, and rarely from the papilla. Here, we report a case of invasive ductal carcinoma confined to the nipple, diagnosed approximately four years after symptom onset. A 70-year-old woman who visited our hospital annually for regular breast examinations noticed a mass in the right nipple ; however, since no abnormalities were observed on mammography and ultrasonography, the patient continued her annual regular check-ups. Three years after symptoms onset, ultrasonography revealed a 7.8 × 6.3 mm hypoechoic mass within the right nipple. The following year, ultrasonography showed no change in the size of the mass in the right papillary region ; however, because of worsening mass tightness and pain, punch biopsy was performed. The pathological diagnosis was invasive ductal carcinoma. Right cylindrical segmental resection, including the nipple areola, was performed. Histopathological diagnosis was invasive ductal carcinoma confined to the right papilla. One and half years postoperatively, the patient survived without recurrence.

The patient was an 82-year-old man, who received a 6-month conservative treatment for mediastinitis following aortic valve replacement and coronary artery bypass surgery, underwent omentum and pectoralis major muscle flap filling. Abdominal pain was reported on the 30^th postoperative day, and a plain computed tomography showed a small intestine prolapse under the skin anterior to the sternum. The primary consideration was intestinal obstruction due to a subxiphoid incisional hernia, and emergency surgery was performed. The small intestine was pulled to release the hernia. The small intestine and its vascular supply were preserved. The hernial orifice was closed via a simple ligation suture by placing the subcutaneous tissue on the sternum. He started oral intake on the fifth postoperative day and was transferred to other hospital on the 12^th postoperative day. His abdominal pain recurred on the 33^rd postoperative day, and a recurrent hernia was observed. No strangulation was observed, and semi-emergency operation was performed after the mesh had been prepared. The small intestine was pulled laparoscopically into the abdomen and repaired by the keyhole method using the mesh. Oral intake was resumed on the fourth postoperative day, and he was transferred to the hospital eight days later. He died of another disease five months postoperatively. However, recurrence of the hernia was not observed.

A 76-year-old woman was admitted to our hospital because of abdominal bloating and poor oral intake. An abdominal computed tomography showed a complicated esophageal hiatal hernia involving prolapse of the small intestine without dilatation and marked dilatation of the stomach. Upper gastrointestinal imaging showed a small intestine to have passed over the ventral side of the pylorus and protruded into the mediastinum. We made a diagnosis of complicated esophageal hiatal hernia involving prolapse of the small intestine and pyloric stenosis due to compression by the prolapsed small intestine. We performed laparoscopic hernia repair. Intraoperatively, the small intestine had prolapsed in the mediastinum through both an abnormal hiatus in the transverse mesocolon and the esophageal hiatus. The definite diagnosis was complicated esophageal hiatal hernia with transverse mesocolon hernia. After the prolapsed small intestine was returned, both esophageal hiatal hernia and transverse mesocolon hernia were repaired. Here we report a rare case of a complicated esophageal hiatal hernia with transverse mesocolon hernia.

A 73-year-old woman underwent coronary artery bypass grafting and aortic valve replacement for effort angina and aortic valve stenosis in February 2017, and she was put on aspirin and warfarin potassium after the surgery. In October, anemia was found on a blood test, and esophagogastroduodenoscopy showed bleeding from gastric antral vascular ectasia (GAVE). She had recurrent bleeding from the GAVE, and argon plasma coagulation (APC) was performed 20 times from then to 2020. An echocardiogram in June 2020 showed hypokinesis caused by ischemia due to decreasing blood flow of the bypass graft, and percutaneous coronary intervention (PCI) was performed. In addition, her renal function was decreasing gradually, and initiation of dialysis was planned. Since the risk of bleeding from the GAVE was expected to increase with dual antiplatelet therapy after PCI and anticoagulation during dialysis, this case was considered a candidate for surgery. In August 2020, laparoscopic distal gastrectomy (LDG) was performed for the GAVE, and she was discharged on postoperative day 11 with a good postoperative course. No bleeding from the stomach has been observed up to 26 months after the surgery. LDG is safe and should be considered as an early surgical treatment option for GAVE.

A 72-year-old man with previous gastric volvulus treated by conservative therapy visited the previous hospital because of upper abdominal pain and vomiting. Abdominal X-ray examination and plain computed tomography (CT) showed gastric dilatation and volvulus. He was diagnosed as having gastric volvulus and received conservative therapy, but his symptoms did not improve. An additional contrast-enhanced CT showed free air in the upper abdomen, although the volvulus was resolved. With the diagnosis of gastric perforation secondary to gastric volvulus, he was transferred to our hospital for emergency surgery. At the time of arrival at our hospital, the abdomen was firm and board-like, and tenderness was observed in the epigastrium. During the operation, a 10-mm-diameter perforation was found in the posterior wall of the stomach. Gastric fixation was poor. The perforation was sutured closed, and the gastric fornix was suture-fixed to the left diaphragm to prevent recurrence of gastric volvulus. He was discharged on the 10^th postoperative day without any complications. Since gastric perforation secondary to adult idiopathic gastric volvulus is rare, this case is reported along with a review of the relevant literature.

Adenocarcinoma arising from an ectopic pancreas of the stomach is rare. The case of a 77-year-old woman with adenocarcinoma arising from an ectopic pancreas of the stomach after endoscopic submucosal dissection (ESD) for early-stage gastric cancer is reported. Seven years after ESD, her tumor marker (CA19-9) level was elevated. Contrast-enhanced computed tomography (CT) showed a 25-mm mass near the pylorus. Positron emission tomography-CT showed abnormal uptake of 18F-fluorodeoxyglucose. Endoscopic ultrasonography (EUS) showed the mass located out of the stomach, and EUS-guided fine-needle aspiration was performed. Histological examination demonstrated adenocarcinoma, but the degree of differentiation was different from that of the previous gastric cancer. Distal gastrectomy with D2 lymph node dissection was performed, suspecting a lymph node recurrence of the previous gastric cancer. Pathological examination showed a moderately differentiated adenocarcinoma surrounded by ectopic pancreas of Heimlich type I, located in the submucosal and subserosal layers near the pyloric ring. The lesion was not exposed to the mucosal surface. Pancreatic ductal tissue was found at the border of the tumor, and carcinoma in situ was found inside the duct. Based on these findings, the tumor was diagnosed as adenocarcinoma arising from an ectopic pancreas of the stomach.

A 69-year-old man was brought to the ER with melena. Contrast-enhanced computed tomography showed intra-luminal bleeding of the small intestine. Emergent laparoscopic surgery was performed, but the bleeding point could not be detected. The patient showed progressive anemia. Since small bowel endoscopy could not be performed, a long nasal tube was inserted to try to identify the site of bleeding, focusing on the changes in drainage fluid characteristics as the ileus tube was advanced. A small incision was made from the tip of the ileus tube, and the source of the bleeding was identified by observation using a gastrointestinal endoscope. Obscure gastrointestinal bleeding (OGIB), which is often caused by a lesion of the small intestine, could be difficult to treat in cases where small bowel endoscopy is not available. In the present case, it was possible to identify the site of small intestinal bleeding using an ileus tube, which is easy to use in everyday practice. We believe that this simple method of identifying the source of bleeding using an ileus tube is highly useful, though there have been only a few reports of this method.

There have been some reports of laparoscopic appendectomy for acute appendicitis during pregnancy, but there are still few cases of those in third trimester. A 30-week pregnant patient was referred to our department with a diagnosis of acute appendicitis. By devising the intraoperative position and the port arrangement, we could complete laparoscopic appendectomy safely without affecting the uterus. We thought feasible to conduct laparoscopic surgery in our patient even in third trimester. In case of perforated appendicitis or that with abscess formation, it is predicted that the enlarged uterus will make difficult to secure enough operative field or to achieve sufficient intraperitoneal lavage. Laparoscopic appendectomy might be useful for selected patients during third pregnancy trimester, however, in some cases, it must be desirable to convert the operation to open to ensure the safety of patients and their fetuses.

The patient was a 55-year-old man who came to our emergency department with a complaint of epigastric discomfort, but no tenderness of the abdomen. The laboratory tests showed inflammatory reaction. Despite these negative findings, an abdominal contrast-enhanced computed tomography scan showed a cystic lesion with marked caliber change at the root of the appendix, which was a clear-cut sign of appendiceal torsion. At emergency surgery, the appendix was found to be twisted 180 degrees at the root, and it was dark-blue in color. An appendectomy was safely carried out after release of the torsion. The patient had a good postoperative course.

Appendiceal torsion is a rare condition for which preoperative diagnosis is difficult, and perforation is not an uncommon complication. It is necessary to include appendiceal torsion in the differential diagnosis of appendicitis, and not to overlook its characteristic findings on CT.

A 44-year-old woman was referred to our department for a subcutaneous mass in the umbilical region. She had been aware of the mass for a year. At first we had thought it as a ureteral duct cyst and performed an abdominal CT scan for detailed examination. The CT findings revealed a multifocal cystic mass in the appendix. Laparoscopic surgery was performed with a preoperative diagnosis of an umbilical mass and low-grade appendiceal mucinous neoplasm (hereinafter referred to as LAMN). The appendiceal tumor was partially ruptured and a localized jelly-like ascites effusion was observed around the ileocecal area. The ileocecal area was resected with the peritoneum covering the ileocecal area in order to prevent the spread of ascites. The pathological findings were compatible with the diagnosis of LAMN and peritoneal pseudomyxoma peritonei (PMP)including umbilical cysts. The patient underwent adjuvant chemotherapy and has been recurrence-free for 1 year and 4 months. We report a case of PMP presented with simultaneous umbilical metastasis, which is extremely rare.

A 54-year-old woman with a history of sigmoid graft vaginoplasty and ulcerative colitis underwent total colectomy and neovaginectomy because of colonic and neovaginal bleeding. This is the first case in Japan in which a patient underwent total colectomy and neovaginectomy for ulcerative colitis after vaginoplasty. This case is reported along with a review of the relevant literature.

A 78-year-old woman underwent right hemicolectomy for cancer in the hepatic flexure of the transverse colon. Histologically, it was poorly differentiated adenocarcinoma, RAS mutation-negative, BRAF mutation-positive, and MSI-H. Since the resection margin was positive, mFOLFOX6 was performed from 4 weeks after the operation. After completion of 3 courses, a contrast-enhanced CT scan revealed a recurrence of 50 mm in size on the ventral side of the pancreatic head and 42 mm in size on the ventral side of the right greater psoas muscle, involving the ureter. He had a history of Basedow disease. Considering a risk of causing thyrotoxicosis as an immune-related adverse event of pembrolizumab, encorafenib + binimetinib + cetuximab therapy was started as second-line therapy. After 9 courses, the tumor disappeared leaving only a soft shadow, and a complete response was obtained on imaging. Meanwhile the regimen became unsustainable due to the infusion reaction. Since the curative resection was judged to be possible, pancreatoduodenectomy and right ureter combined resection and reconstruction were performed, and no tumor cells were found histopathologically. This is the first report in Japan of a complete pathological response to chemotherapy for BRAF-mutant colorectal cancer.

A 49-year-old man presented with abdominal pain. A contrast-enhanced computed tomography (CT) scan showed multiple diverticula in the sigmoid colon and irregular wall thickening with increased peribronchial fatty tissue density, with abscess formation in the vicinity of them. The left ureter was severed at the lesion, and left hydronephrosis was observed. We diagnosed the case as an intra-abdominal abscess due to perforation of a sigmoid colon diverticulum. We had a plan to create a stoma emergently, followed by elective laparoscopic surgery. A fluorescent ureteral catheter was placed in the left ureter, and a laparoscopic sigmoid colon resection was performed. The retroperitoneal side was highly fibrotic, making it difficult to visualize the ureter. However, near-infrared light observation was used to clearly visualize the ureter and ensure its preservation. In cases where ureteral injury is feared, ureteral catheters have been placed prophylactically, but their visibility has been poor. Recently, fluorescent ureteral catheters have attracted attention as a device to improve visibility. We report the findings of our own case with a review of the literature.

A 79-year-old woman visited our hospital complaining of abdominal distention and vomiting. She was diagnosed with cT4b(duodenum) N1aM0 Stage IIIc ascending colon cancer. A self-expandable metallic stent was placed in order to start oral intake and rehabilitation immediately, and subtotal stomach-preserving pancreaticoduodenectomy accompanied by right hemicolectomy was performed. Total operation time was 317 min, with blood loss of 170 g. She was discharged on postoperative day 19, and 3 months have passed with no indication of recurrence. Preoperative colonic stenting for obstructive colon cancer invading to the duodenum seemed to be a beneficial strategy in terms of preoperative improvement of patients' nutritional status and ADL, which may lead to a better perioperative outcome for this complex and rare disease condition.

Sigmoid diverticulitis rarely develops a fistula to the urinary bladder, often requiring a difficult and long-term treatment. We report a case of a patient suffering from a colovesical fistula through an abscess in the broad ligament of the uterine. A woman 49-year-old was presented to a clinic with repeated pain when urinating for 8 months. She was referred to our hospital with a diagnosis of colovesical fistula due to gas image in the urinary bladder by a CT scan. A CT scan soon after gastrografin enema during sigmoidoscopy showed a contrasted urinary bladder including both renal pelves, suggesting the presence of a fistula. Then we performed laparoscopic surgery with the diagnosis of colovesical fistula. Sigmoid diverticulitis firmly adhered to the urinary bladder through the left side of the broad ligament of uterine. After breaking up adhesions and confirming a negative leak test from the bladder, we performed partial sigmoidectomy without repair of the bladder. Her postoperative course was uneventful and she was discharged on the 11th day postoperatively. No evidence of recurrence was seen for these 2 years.

A loop colostomy was created in the transverse colon in a 66-year-old man with locally advanced sigmoid colon cancer and obstructive colitis. The patient underwent neoadjuvant chemotherapy (FOLFOXIRI+bevacizumab therapy), laparoscopic sigmoidectomy and colostomy. As the colostomy was not closed, adjuvant chemotherapy (mFOLFOX6 therapy) was performed. Five months after sigmoidectomy, complete occlusion of the anastomosis was confirmed via barium enema, before colostomy closure. Surgical resection of the anastomotic site and high-frequency incision using an endoscopic laser were considered. However, magnetic compression anastomotic stenosis release (second Yamauchi method), which is the least invasive method, was performed. After confirming the anal exit of the magnets and endoscopically verifying good patency of the anastomotic site, colostomy closure was performed on the fifth day. Defecation after the procedure was good. One year later, additional dilation was not required, and the anastomosis remained patent.

This method can be an effective and minimally invasive treatment option for the complete occlusion of an anastomosis after lower gastrointestinal surgery.

Intestinal amyloidosis is a rare disease that causes tissue fragility due to amyloid protein deposition in the vascular and intestinal walls. The case of a 66-year-old man who was brought to our hospital by ambulance complaining of sudden lower abdominal pain and melena is presented. Intramesorectal hemorrhage was diagnosed, and emergency surgery was performed. Intraoperatively, a hematoma was observed within the mesorectum, and there was a laceration measuring approximately 3 cm in the posterior wall of the lower rectum (Rb). Hartmann's procedure was performed, including the laceration site and the hematoma. The mucosa of the resected specimen appeared normal on visual examination, but histopathological investigations showed amyloid deposition in the vascular walls of the full thickness of the intestine, and intestinal amyloidosis was diagnosed. It was thought that blood vassels in the mesentery had become fragile and broken down, leading to hematoma formation and rectal perforation. Although intestinal amyloidosis is a known risk factor for mesenteric hemorrhage, only two cases of small bowel mesenteric hemorrhage have previously been reported, including in the foreign literature. Intestinal amyloidosis should be included in the differential diagnosis of cases of intramesenteric hemorrhage or perforation of unknown origin.

The patient was an 86-year-old woman who was admitted to another hospital with a diagnosis of acute cholecystitis and acute cholangitis. She had repeated biliary hemorrhages and was referred to our hospital. Contrast-enhanced computed tomography and angiography showed a ruptured intrahepatic pseudoaneurysm with portal vein thrombosis. Endovascular treatment of the hepatic aneurysm was considered to prevent rebleeding, but it was not performed because of the risk of hepatic ischemia due to insufficient portal vein and hepatic artery blood flow. Left hepatectomy was performed after obtaining the patient's consent. Postoperatively, abscess formation was observed on the dissected surface of the liver, but the patient was discharged from the hospital on the 49th postoperative day after treatment with antibacterial drugs and drainage. Hepatic aneurysms occur infrequently, and ruptures are potentially fatal, requiring the selection of an appropriate treatment strategy. Although endovascular treatment has been widely used in recent years, there is no clear treatment strategy for hepatic aneurysms with portal vein thrombosis because of the risk of hepatic ischemia due to occlusion of the hepatic artery. This case is reported along with a review of the literature.

A 74-year-old man undergoing chemotherapy for left ureteral cancer presented to our hospital with epigastric pain. Blood tests showed elevated inflammatory response, biliary enzymes and bilirubin, and a plain computed tomography scan showed dilatation of the umbilical cord, enlargement and internal abscess formation along the entire length of the hepatic round ligament. Although conservative treatment was initially chosen, surgery was subsequently performed due to prolonged inflammatory reaction and exacerbation of the abscess on CT. We resected the inflammatory thickened round ligament of the liver, suture closed the umbilical cord disconnection, and placed drains in the abdominal cavity. Bacteriological examination of the abscess revealed Klebsiella pneumoniae. Histopathological examination showed thickening of the umbilical vein wall, lumen obstruction, and inflammatory cell infiltration into the surrounding fatty tissue. Though the patient suffered from postoperative paralytic ileus, he was discharged on the 31st postoperative day without recurrence of the abscess. A round ligament of liver abscess is a remarkably rare cause of acute abdomen. This case of the disease developed during chemotherapy is valuable as no case has been reported in the past.

A 71-year-old man who had been pointed out having gallstone was diagnosed with cholelithiasis and adenomyomatosis by preoperative abdominal MRI. Laparoscopic cholecystectomy was performed. The resected specimen included a 25-mm submucosal tumor-like ridging that was found to be a multilocular cystic lesion on the section. Histopathology disclosed adenmyomatosis and multilocular cystic lesion due to mucinous epithelium localized in the gallbladder wall. The cystic epithelium was partly positive for MUC5AC and MCU6, that characterized of gastric-type mucus, with a part comprising low-grade atypical epithelium. Our case was of an intramurally growing cystic lesion localized in the gallbladder wall. Morphologically, it is designated as intramural multicystic mucinous neoplasm with low-grade intraepithelial neoplasia. Due to the rarity of pathological features, we here present this case.

A 62-year-old man visited our hospital complaining of a positive fecal occult blood test. The patient had a history of hernia repair with a mesh plug at another hospital two years previously. Colonoscopy revealed a tumor that appeared as a plug in the lumen of the sigmoid colon, and computed tomography (CT) revealed a mass between the sigmoid colon and the abdominal wall. We planned a laparoscopic surgery for the diagnosis of a colonic fistula due to a mesh plug. Intraoperative findings showed that the plug had adhered to the sigmoid colon ; therefore, a laparoscopic sigmoidectomy was performed. We did not remove the onlay mesh or reinforce the posterior inguinal wall. The patient was discharged 12 days after the surgery with no complications and did not experience a hernia recurrence one year later. We experienced a case of laparoscopic sigmoidectomy for a colonic fistula caused by a mesh plug. Laparoscopic surgery seemed feasible in cases without infection, and posterior wall reinforcement seemed unnecessary.

Radical surgery for an inguinal hernia after kidney transplantation is helpful to avoid the risk of damage to the transplanted nephroureter, which runs through the preperitoneal space and anastomoses the bladder without preperitoneal dissection. We encountered a case in which an inguinal hernia developed on the graft side two years after living-donor kidney transplantation and was repaired using the Lichtenstein method. A right inguinal hernia was found during follow-up and repaired by inserting a polypropylene mesh using the Lichtenstein method. No exacerbation or recurrence of the hernia occurred. Reports revealed that 4.9% of kidney transplant patients develop an inguinal hernia on the graft side. In the last 12 years, 29 cases of inguinal hernia surgery after kidney transplantation have been reported. We will report these cases with a consideration of the literature.

We report a case of femoral hernia with an incarcerated transverse colon in an elderly patient. A 92-year-old woman visited another hospital with a complaint of anorexia and was referred to our hospital with a diagnosis of femoral hernia. An abdominal CT revealed that the transverse colon was incarcerated in the right inguinal region, while the oral side of the intestine was dilated from the same region. Since the hernia could not be reduced by manipulation, an emergency operation was performed under general anesthesia. The presence of a fist-sized hernia sac that was located caudal to the inguinal ligament led to a diagnosis of femoral hernia. The hernial contents were the transverse colon and omentum. An absence of necrosis was noted, and subsequently, the transverse colon was repositioned in to the abdominal cavity through an additional incision in the lower abdomen. The hernia sac was ligated, and a flat mesh was placed in the preperitoneal space and fixed to the Cooper's ligament. A seroma was discovered after surgery;however, the patient was discharged home on the 21st postoperative day.