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Background: The observation of spontaneous regression (SR) has been well documented for many cancer types, including renal cell carcinoma, non-Hodgkin's lymphoma, leukemia, neuroblastoma, and malignant melanoma. However, the SR frequency in colorectal cancer is very rare. Therefore, the accumulation of SR colorectal cancer cases might contribute to find the regression mechanism. Case presentation: A 67-year-old woman received colonoscopy due to being positive for fecal occult blood testing and was diagnosed as having a transverse colon cancer at a local hospital. She was admitted to our institution for surgical treatment of the colon cancer. The colonoscopy revealed a type 2 tumor of 13 mm in diameter at the hepatic flexure of the transverse colon. The enhanced computed tomography (CT) showed an enlarged lymph node in the intermediate lymph node region. The 18F-fluorodeoxyglucose positron emission tomography/CT showed no abnormal accumulation on the transverse colon; however, an abnormal accumulation was found at the enlarged lymph node. The patient was preoperatively diagnosed as having advanced transverse colon cancer with lymph node metastasis and underwent laparoscopic right hemicolectomy with D3 lymph node dissection. Pathological examination showed only a scar-like tissue and no cancerous lesion in the transverse colon, while a metastatic lymph node was histologically confirmed in the intermediate lymph node region. Loss of MLH1 and PMS2 expression was observed in the cancer cells of both biopsy specimens and resected lymph nodes. No recurrence was seen for 5 years after surgery. Conclusions: We reported a rare case of SR of the primary transverse colon cancer without regression of the metastatic regional lymph node. We considered that colorectal cancer with SR should be resected because even if SR of the primary lesion occurs, lymph node metastasis might have an inconsistent behavior as shown in the present case. [ABSTRACT FROM AUTHOR]

Background: Persistent descending mesocolon (PDM) is a congenital anomaly associated with the failure of fixation of the descending colon to the lateral abdominal wall. In the laparoscopic colectomy for colorectal cancer, it has been noticed that there are extensive adhesions and a distinctive anatomy of colonic vessels in cases with PDM. Therefore, it is necessary to have sufficient knowledge about PDM so that it can be appropriately treated during surgery. Case presentation: Case 1—a 79-year-old man underwent laparoscopic intersphincteric resection for rectal cancer. Preoperative barium enema (BE) revealed that the sigmoid colon was located at the right side of the abdomen. An enhanced computed tomography (CT) showed that the common trunk of the left colic artery (LCA) and the first sigmoid colonic artery (S1) branched from the inferior mesenteric artery (IMA). Case 2—a 68-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer and laparoscopic distal gastrectomy for gastric cancer synchronously. BE showed that the descending colon ran from the splenic flexure to medial caudal side. An enhanced CT showed that the distance from the LCA to the marginal artery was 1.0 cm. Case 3—a 68-year-old man underwent laparoscopic low anterior resection for rectal cancer. BE showed that the descending colon ran to the medial caudal side. An enhanced CT showed that the mesentery of the descending colon was comparatively shortened. Case 4—a 60-year-old man underwent laparoscopic sigmoidectomy for sigmoid colon cancer. An enhanced CT showed that the descending colon ran to the medial caudal side and predicted that the LCA and S1 formed a common trunk and branched radially from the IMA. We reported four cases with PDM recognized preoperatively as above. Three cases had a shortening of the mesocolon. While dissecting the vessels, although special attention was required to maintain the blood flow to the intestine, none of these cases developed any complications during the postoperative course. Conclusions: We considered that it is important to have positional awareness of the LCA and the marginal artery to perform the laparoscopic surgery safely when a colorectal cancer with PDM is diagnosed preoperatively using imaging methods. [ABSTRACT FROM AUTHOR]

Background: Schloffer tumor is a foreign body granuloma in the abdominal subcutaneous layer that develops due to a foreign body such as suture from several months to years postoperatively. Herein, we report a case of a rapidly growing Schloffer tumor with F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) positivity at the port site of laparoscopic sigmoidectomy for colon cancer. Case presentation: An 85-year-old man, who underwent laparoscopic sigmoidectomy for stage IIIa sigmoid colon cancer 10 months ago, was referred to our hospital with complaints of a growing mass in the abdominal wall. The tumor was palpable at the right-sided abdominal wall corresponding to the port site of laparoscopic sigmoidectomy. The tumor rapidly grew for 2 months. Computed tomography showed a ring-enhanced mass at the right-sided abdominal wall. PET examination revealed high accumulation of FDG in the tumor. Tumor resection was performed due to suspected port site recurrence. The pathological diagnosis was inflammatory granuloma, so-called Schloffer tumor. Conclusion: In the era of laparoscopic surgery, Schloffer tumor may be one of the differential diagnoses for rapidly growing tumor with FDG-PET positivity at the port site in postoperative patients with advanced colorectal cancer. [ABSTRACT FROM AUTHOR]