Circulating cell-free DNA methylation patterns as non-invasive biomarkers to monitor colorectal cancer treatment efficacy without referencing primary site mutation profiles.

This study investigates methylation patterns in circulating cell-free DNA (ccfDNA) for their potential role in colorectal cancer (CRC) detection and the monitoring of treatment response. Through methylation microarrays and quantitative PCR assays, we analyzed 440 samples from The Cancer Genome Atlas (TCGA) and an additional 949 CRC samples. We detected partial or extensive methylation in over 85% of cases within three biomarkers: EFEMP1, SFRP2, and UNC5C. A methylation score for at least one of the six candidate regions within these genes' promoters was present in over 95% of CRC cases, suggesting a viable detection method. In evaluating ccfDNA from 97 CRC patients and 62 control subjects, a difference in methylation and recovery signatures was observed. The combined score, integrating both methylation and recovery metrics, showed high diagnostic accuracy, evidenced by an area under the ROC curve of 0.90 (95% CI = 0.86 to 0.94). While correlating with tumor burden, this score gave early insight into disease progression in a small patient cohort. Our results suggest that DNA methylation in ccfDNA could serve as a sensitive biomarker for CRC, offering a less invasive and potentially more cost-effective approach to augment existing cancer detection and monitoring modalities, possibly supporting comprehensive genetic mutation profiling.

Endoscopic Surgical Skill Qualification System: propensity-score matched cohort analysis of accredited supervisors in laparoscopic rectal cancer surgery.

BACKGROUND: The Endoscopic Surgical Skill Qualification System (ESSQS) in Japan evaluates the surgical skills required for laparoscopic surgery as an operator as well as a supervisor. This study aimed to demonstrate the benefits of an ESSQS-certified surgeon's participation in laparoscopic rectal resections as a supervisor (assistant or advisor). METHODS: We retrospectively reviewed laparoscopic resection results for cStage II and III rectal cancer performed at 56 Japanese hospitals between 2014 and 2016. We used propensity score matching to generate paired cohorts with or without an ESSQS-certified supervisor at a one-to-one ratio. The impact of ESSQS-certified supervisors' participation on short-term outcomes was assessed. In the matched cohort, multivariable logistic regression analysis and multivariable regression analysis of postoperative complication rate and intraoperative blood loss were performed to further mitigate the impact of pathological factors. RESULTS: Two groups (n = 399 each) with or without an ESSQS-certified supervisor were well matched by clinical factors. The group with an ESSQS-certified supervisor had lower blood loss (68 mL vs. 98 mL, P = 0.036) and a lower incidence of severe morbidities of Clavien-Dindo grade ≥IIIa (8.0% vs. 13.3%, P = 0.016). Multivariable logistic regression analysis and multivariable regression analysis confirmed that the attendance of ESSQS-certified supervisors reduced postoperative complication occurrence (adjusted odds ratio: 2.28, 95% confidence interval: 1.38 - 3.80, P = 0.001) and intraoperative blood loss (estimated difference: -15.7 mL, P = 0.016). CONCLUSION: This study demonstrated the educational benefits of ESSQS-certified supervisors, including assistants and advisors, evidenced by their superior short-term outcomes.

A Custom-Made Surgical Guide for Accurate Enucleation of Nasopalatine Duct Cysts: A Technical Note and Case Report.

Nasopalatine cysts are common nonodontogenic cysts that occur in the maxilla. During the nucleation of large cysts extending to the floor of the nasal cavity, care must be taken to avoid damage to the nasal mucosa. In the present report, an innovative custom-made surgical guide made by a Three-dimensional printer is introduced for accurate enucleation surgery. The patient's cone-beam computerized tomography and dental model scan data were obtained, and a tooth-supported type of surgical guide was designed containing a circular plate structure showing the size of the cystic region, an indicator that showed the position of the bottom of the cyst, and a sliding stopper that was used to accurately indicate the position of the deepest cyst wall. The surgical tool enabled us to indicate the accurate size, location of the cysts, and approach direction. Although effective and accurate navigation systems have become increasingly available, the cost-effective and accurate computer-aided design/computer-aided manufacturing surgical guide system introduced in the present report could support the safe enucleation of large nasopalatine duct cysts.

Internal hernia caused by exposed structures after laparoscopic lateral lymph node dissection for rectal cancer: A case report.

Internal hernias secondary to exposed structures after lateral lymph node dissection (LLND) for rectal cancer are rare. A 53-year-old man who underwent laparoscopic ultra-low anterior resection and bilateral LND presented to our emergency department with sudden-onset severe abdominal pain and vomiting. Computed tomography demonstrated a closed loop obstruction of the intestine in the right lateral pelvic cavity and a significantly dilated small bowel in the abdominal cavity. Laparoscopic surgery revealed small bowel migration into the space between the right ureter and umbilical artery. The herniated bowel was laparoscopically reduced, and the small bowel exhibited no ischemic changes. Meanwhile, the hernial orifice was left unrepaired. The patient was discharged on the seventh postoperative day without complications. An internal hernia caused by exposed structures after lymphadenectomy should be a differential diagnosis in patients who have undergone LLND for rectal cancer and then present with severe abdominal pain and vomiting.

Laparoscopic versus open resection for stage II/III rectal cancer in obese patients: A multicenter propensity score-based analysis of short- and long-term outcomes.

Aim: Whether a laparoscopic procedure can contribute to the improvement of clinical outcomes in obese patients with stage II/III rectal cancer compared to an open procedure remains unclear. Objective: This study evaluated the technical and oncological safety of laparoscopic surgery versus open surgery in obese patients (body mass index [BMI] ≥25 kg/m2) with rectal cancer. Patients and Methods: Data were collected from patients with pathological stage II/III rectal cancer and analyzed. Operations were performed via laparoscopic or open surgery from 2009 to 2013. A comparative analysis was performed after applying propensity score matching to the two cohorts (laparoscopic group and open group). The primary endpoint was 3-y relapse-free survival (RFS). Results: Overall, 524 eligible cases were collected from 51 institutions. Equal numbers of propensity score-matched patients were included in the laparoscopic (n = 193) group and open (n = 193) group. Although the rate of D3 lymph node dissection did not differ between the laparoscopic group (87.0%) and the open group (88.6%), the median number of harvested lymph nodes was significantly lower in the laparoscopic group versus open group (17.5 vs 21, P = 0.0047). The median postoperative hospital stay was also significantly shorter in the laparoscopic group (14 d) vs the open group (17 d) (P = 0.0014). Three-y RFS was not significantly different between the two groups (hazard ratio 1.2454, 95% confidence interval 0.9201-1.6884, P = 0.4689). Conclusion: The short- and long-term results of this large cohort study (UMIN ID: UMIN000033529) indicated that laparoscopic surgery in obese rectal cancer patients has advantageous short-term outcomes and no disadvantageous long-term outcomes.

Skin and Bone Regeneration of Solid Bone Marrow Aspirate Concentrate Versus Platelet-Rich Fibrin.

Solid bone marrow aspirate concentrate (sBMAC) is harvested from bone marrow aspirate without anticoagulants by a centrifugation protocol similar to that for platelet-rich fibrin (PRF) prepared from peripheral blood. It was hypothesized that sBMAC could accelerate not only wound healing but also bone regeneration because of the abundant growth factor (GF) releases from enriched bone marrow cells. The purpose of the present study was to investigate skin wound healing and bone regenerative potential of sBMAC compared with arterial blood-derived PRF (Ar-PRF) and venous blood-derived PRF (Ve-PRF) in a skin defect and calvarial bone defect model in rabbits. GF release assays revealed significantly higher release of transforming growth factor-ß (TGF-ß), alkaline phosphatase (ALP), and osteocalcin (OCN) from sBMAC compared with PRFs for 24 h. In the skin defect animal model, sBMAC and PRFs promoted wound bed angiogenesis and re-epithelization in skin defect sites with higher collagen 1 synthesis, cytokeratin AE1/AE3, vascular endothelial growth factor (VEGF) expressions on week 1. Furthermore, a calvarial defect assay revealed that sBMAC promoted new bone formation with a sufficient bone marrow structure similar to that of intact bone in the bone defects. Ar-PRF achieved the second highest bone closure and new bone volume but yielded new bone that was thinner than the intact bone. In conclusion, sBMAC treatment might be a good option instead of PRF as an adjuvant therapy for both skin and bone tissue regeneration therapies in certain clinical situations. Impact statement Solid bone marrow aspirate concentrate (sBMAC) is new type of clot material prepared from bone marrow aspirate. The present study for the first time showed that sBMAC significantly accelerated both skin wound healing and bone formation in the defects, compared with conventional platelet-rich fibrin in rabbit experiment models.

Preclinical study for the treatment of diabetes mellitus using ß-like cells derived from human dental pulp stem cells.

Aim: The current study assessed whether insulin-producing cells obtained from dental pulp stem cells (DPSCs) can be a new therapeutic approach in a rat model of diabetes mellitus (DM). Materials & methods: Stem cells were differentiated into pancreatic ß cells under hydrogen sulfide exposure via 2D and 3D methods. Each ß-like cell was immunostained and transplanted into DM rats, after which the in vivo therapeutic effect was determined. Results: Immunostaining revealed the expression of various ß-cell markers in each ß-like cell differentiated using the 3D method. DPSC-derived ß-like cell differentiated via the 3D method promoted a sufficient therapeutic effect. Conclusion: The 3D method promoted islet differentiation, indicating that DPSC-derived ß-like cell transplantation could be a new approach for DM treatment.

Phase 3 trial of sequential versus combination treatment in colorectal cancer: The C-cubed study.

BACKGROUND: An optimal treatment strategy using oxaliplatin and bevacizumab for metastatic colorectal cancer has not been defined. We investigated whether the sequential treatment using fluoropyrimidines with bevacizumab followed by the addition of oxaliplatin at first progression was better than a combination treatment using fluoropyrimidines and oxaliplatin with bevacizumab. METHODS: In the sequential treatment, the escalation from fluoropyrimidines plus bevacizumab to fluoropyrimidines plus oxaliplatin with bevacizumab was recommended in case of progressive disease. Time to failure of strategy was the primary end-point, whereas the secondary end-points were overall survival, progression-free survival, overall response rate and safety. RESULTS: Three hundred patients with previously untreated metastatic colorectal cancer were randomised to receive either the sequential treatment (n = 151) or the combination treatment (n = 149). The sequential treatment was superior to the combination treatment about time to failure of strategy (15.2 months; 95% CI, 12.5-17.2 months vs. 7.8 months: 95% CI, 6.3-9.5 months; P < 0.001). However, the median overall survival was 27.5 (95% CI, 24.4 to 32.7) months in the sequential treatment and 27.0 (95% CI, 22.8 to 36.0) months in the combination treatment (hazard ratio, 0.92; 95% CI, 0.66 to 1.28; P = 0.61). The overall response rate was 33.1% in the sequential treatment arm and 51.7% in the combination treatment. CONCLUSIONS: The findings support the extension of the sequential treatment starting from fluoropyrimidine plus bevacizumab to selected patients who do not need an objective response to the threatening disease.

Regenerative Potential of Solid Bone Marrow Aspirate Concentrate Compared with Platelet-Rich Fibrin.

Platelet-rich fibrin (PRF) prepared from venous blood is used in the clinic to improve soft tissue wound healing. Nevertheless, arterial blood or bone marrow aspirate might also be a candidate for the source of PRF-like concentrates. The purpose of the present study was to investigate blood/bone marrow aspirate concentrates obtained from arterial blood, venous blood, and bone marrow aspirate to determine its respective regenerative potential in vitro. Arterial blood-derived PRF (Ar-PRF), venous blood-derived PRF (Ve-PRF), and solid-type bone marrow aspirate concentrate (sBMAC) were prepared from New Zealand white rabbits. Each clot was evaluated for its cytocompatibility and regenerative potential on primary rabbit gingival fibroblasts and osteoblasts. Both gingival fibroblasts and osteoblasts treated with each concentrate showed excellent viability. Interestingly, the sBMAC-treated cells demonstrated a significantly greater migratory potential than the other treatment groups. Furthermore, higher mRNA levels of transforming growth factor-beta, vascular endothelial growth factor, and collagen 1 (COL1) in gingival fibroblasts were observed in the sBMAC group compared with the Ar-PRF and Ve-PRF groups. Greater osteoblast differentiation potential, including higher osteocalcin (OCN) expression and mineralization potential, was found in osteoblasts treated with sBMAC. However, minor differences between the behaviors of cells treated with Ar-PRF and Ve-PRF were observed. In conclusion, sBMAC might be a new candidate for promoting wound healing and bone regeneration. Further preclinical and clinical experiments are necessary to prove the regenerative potential of sBMAC in the body. Impact Statement Blood concentrate material such as platelet-rich plasma or platelet-rich fibrin (PRF) is used in clinical practice to promote tissue regeneration in the field of dentistry, orthopedic surgery, and plastic surgery. The present study introduces a new type of solid bone marrow aspirate concentrate material and, for the first time, shows its excellent regenerative potential in both gingival fibroblasts and osteoblasts in vitro compared with that of conventional PRF.

Laparoscopic Synchronous Resection for Descending Colon Cancer and Tailgut Cyst.

A 67-year-old woman underwent polypectomy for a tumor at the descending colon. Pathologically, the tumor was diagnosed as adenocarcinoma with an invasion of 2000 µm. Computed tomography showed a swollen paracolic lymph node and a mass lesion in the presacral space. Magnetic resonance imaging revealed a multio-cular cystic lesion. On diagnosis of descending colon cancer and tailgut cyst, she underwent synchronous lapa-roscopic resection. Histopathologically, the colon cancer was diagnosed as pT1bN1M0, pStage IIIa. The pre-sacral cystic lesion was diagnosed as a nonmalignant tailgut cyst with negative surgical margin. The patient is currently doing well without recurrence at 28 months.

[Successful Resection Using a Posterior Approach of a Tailgut Cyst in the Retrorectal Space].

We present the case of a Tailgut cyst occurring in the retrorectal space that was curatively resected using a posterior approach. A 40-year-old man presented to the Kochi Health Sciences Center with the chief complaint of perineal incongruity. Pelvic magnetic resonance imaging revealed a multilocular cystic lesion in the retrorectal space, with high signal intensity on T2-weighted imaging. After diagnosing a Tailgut cyst, we performed resection of the tumor using a posterior approach. The lesion was removed en bloc with the coccyx. Histopathologically, the lesion was diagnosed as a non-malignant Tailgut cyst, and the surgical margin was negative. The patient is currently doing well without recurrence at 20 months.

The possibility of a transanal tube as an alternative to diverting stoma in terms of preventing severe postoperative anastomotic leakage after laparoscopic low anterior resection.

PURPOSE: The purpose of this study was to reveal whether a transanal tube (TAT) could act as an alternative to a diverting stoma (DS) after laparoscopic low anterior resection. PATIENTS AND METHODS: A total of 89 consecutive rectal cancer patients whose tumors were located within 15 cm from the anal verge who underwent laparoscopic low anterior resection without a DS at our institution between May 12, 2015 and August 31, 2019 were included. All patients received a postoperative Gastrografin enema study (GES) through a TAT between the 3rd and 10th postoperative day. We planned two study protocols. From May 12, 2015 to March 31, 2017, we conducted a second operation including a DS construction immediately when radiological anastomotic leakage (rAL) was detected (Group A, n=46). From April 1, 2017 to August 31, 2019, we continued TAT drainage even if rAL was detected and repeated the GES weekly until the rAL was healed (Group B, n=43). RESULTS: In Group A (n=46), 14 cases of rAL were included, 11 of which underwent stoma construction. The remaining 3 patients who refused stoma construction were treated conservatively. In Group B (n=43) rAL was encountered in 10, and 7 of these patients were treated successfully by TAT continuous drainage. The rate of DS in Group B (7.0%) was significantly lower than that in Group A (23.9%) (p=0.028). CONCLUSIONS: A TAT could act as a DS to mitigate the symptoms of anastomotic leakage after laparoscopic low anterior resection.

Effect of Neoadjuvant Chemotherapy in Patients with Colorectal Cancer Liver Metastases.

BACKGROUND: This study was performed to evaluate the relationships between potential prognostic factors and post-surgery survival in patients with colorectal cancer liver metastasis (CRLM). In particular, this study investigated the value of neoadjuvant chemotherapy as an independent predictor of cancer-specific survival. METHODS: The study participants included 147 patients who underwent resection for CRLM. Demographics, treatments, and relationships between potential prognostic factors and the survival rate were analyzed using a prospective database. RESULTS: The overall 1-, 3- and 5-year cancer-specific survival rates for post-surgery CRLM patients were 94.3%, 71.2%, and 53.5%, respectively. Multivariate analysis revealed that a positive surgical margin and extrahepatic metastasis were independent negative prognostic factors. The administration of neoadjuvant chemotherapy prior to liver surgery did not significantly improve post-surgery outcomes of patients with CRLM. In a subgroup analysis, the time to recurrence in the remnant liver after hepatectomy for CRLM was significantly less in the neoadjuvant group than in the upfront surgery group. CONCLUSIONS: Neoadjuvant chemotherapy was not predictive of cancer-specific survival. The achievement of macroscopically and microscopically negative resection remains the main aim of surgery.

[A Case of Aggressive Angiomyxoma in a 75-Year-Old Man].

Aggressive angiomyxoma is an uncommon mesenchymal tumor that mostly involves the pelvic and perineal regions in young women.We herein report an extremely rare case of aggressive angiomyxoma in a 75-year-old man. The patient had undergone follow-up for an intraductal papillary mucinous neoplasm.In September 2015, CT detected a tumor measuring 33 mm in diameter around the pelvis, and the tumor showed gradual increase in size.MRI revealed a relatively sharply marginated tumor with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images.For treatment and diagnosis, we laparoscopically resected the tumor. Histopathologically, the specimen showed spindle tumor cells within a myxoid background and vascular structures.The tumor was diagnosed as aggressive angiomyxoma, and surgical margins were negative for tumor cells. The patient is currently doing well without any signs of recurrence as of 18 months postoperatively.

Clinical outcomes of women with ovarian metastases of colorectal cancer treated with oophorectomy with respect to their somatic mutation profiles.

We clarified the clinical prevalence of ovarian metastases from colorectal cancers (CRCs) in 296 female patients with CRC and evaluated clinical outcomes with relation to their mutational profiles, such as BRAF/KRAS mutation and microsatellite instability (MSI) status. The female CRCs were categorised into three subsets: CRCs with ovarian metastases [6.4% (n = 19), 5-year overall survival (OS) = 24.7%], CRCs with extra-ovarian metastases only [32.4% (n = 96), 5-year OS = 34.5%] and CRCs without any recurrence or metastasis [61.2% (n = 181), 5-year OS = 91.3%]. All patients with ovarian metastases underwent oophorectomy; of these, 9 who received preoperative chemotherapy had measurable metastases to extra-ovarian sites and the ovaries. Although 5 of 9 (56%) achieved partial response or complete response at extra-ovarian sites, no patient archived objective response at ovarian sites. Regarding the mutation profiles, in CRCs with extra-ovarian metastases only, the median survival time (MST) after initial treatments to progression to stage IV or recurrence was 13 [95% confidence interval (CI): 7-16 months] in BRAF-mutant and 34 months (95% CI: 22-58 months) in BRAF wild-type (P = 0.0033). Although ovarian metastases demonstrated poor response to systemic chemotherapy in CRCs with ovarian metastases, the MST after initial treatments to progression to stage IV or recurrence was 22 (95% CI: 21-25 months) in BRAF-mutant and 38 months (95% CI: 24-42 months) in BRAF wild-type (P = 0.0398). The outcomes of patients with ovarian metastases could be improved by oophorectomy regardless of their mutation profiles.

BRAF V600E mutation is a predictive indicator of upfront chemotherapy for stage IV colorectal cancer.

In stage IV colorectal cancer (CRC), initial resection of the primary tumor is considered to be an important strategy for improving disease outcome. However, there is no consensus on the timing as to when the surgical intervention of the primary tumor should occur. The present study hypothesizes that genetic profiles in CRC may indicate the appropriate treatment strategies for patients with stage IV CRC, and a cohort of 113 patients with stage IV CRC resected primary lesions at various periods were analyzed for the presence of mutations in the KRAS, exon 2, and BRAF genes, exon 15, and for the microsatellite instability status of the tumor. These data were additionally correlated with various clinicopathological features. Although BRAF-mutant was revealed to be an independent negative prognostic factor in stage IV CRC (HR, 8.42; 95% confidence interval, 2.72-26.02), BRAF-mutant samples exhibited better prognoses if they were treated with chemotherapy prior to tumor resection. Thus, the presence of BRAF mutations provides a compelling rationale for the establishment of intensive upfront chemotherapy to improve survival in stage IV CRC.

Comparison of outcomes between symptomatic and asymptomatic patients with colorectal cancer: a propensity score-matched analysis of surgical invasiveness, medical costs and oncological outcomes.

BACKGROUND AND AIMS: Whether asymptomatic patients with colorectal cancer (CRC) who are treated in hospitals show better outcomes than symptomatic patients with CRC still remains unknown. The aim of this study was to evaluate differences in clinical benefits following treatment in asymptomatic and symptomatic patients with CRC. METHODS: This study was a retrospective cohort analysis with data obtained from records. A cohort of 145 asymptomatic and 123 symptomatic patients who underwent CRC surgery between January 2009 and December 2011 was enrolled. To reduce bias in comparing outcomes, propensity score (PS) analysis was used for matching of patients in the symptomatic and asymptomatic groups based on clinicopathological factors. Surgical invasiveness, medical costs and oncological outcomes were examined by unadjusted and PS-matched analysis. RESULTS: Tumours in the symptomatic group were more often diagnosed in advanced stages compared with tumours in the asymptomatic group. Therefore, fewer symptomatic group patients underwent minimally invasive surgery. Short-term outcomes, including amount of blood loss, duration of postoperative hospital stay and perioperative medical costs, were significantly better in the asymptomatic group. Although overall survival was significantly better in the asymptomatic group, there was no significant difference between the groups when the patients were adjusted on the basis of PS. CONCLUSIONS: Though this study was limited by the retrospective nature and small sample size, favourable outcomes in asymptomatic patients were due to the higher proportion of patients in this group who were diagnosed with CRC in earlier stages, due to participation in CRC screening programmes.

[Two Successful Cases of Surgical Treatment of Reconstructed Gastric Tube-Bronchial Fistula after Esophagectomy for Esophageal Cancer by Pedunculated Latissimus Dorsi Flap].

We herein report 2 cases of successful surgical treatment of reconstructed gastric tube-bronchial fistulas caused by leakage after esophagectomy for esophageal cancer. One patient was a 56-year-old man who developed a reconstructed gastric tube-bronchial fistula, and the fistula was closed by conservative treatment. However, he developed pneumonia on postoperative day 117, and the reconstructed gastric tube-bronchial fistula was found to have recurred. Fibrin glue was endoscopically injected into the fistula, but this treatment was unsuccessful. The other patient was a 60-year-old man who developed a reconstructed gastric tube-bronchial fistula and severe pneumonia, and his condition did not improve by conservative treatment. We performed a reoperation for both patients using a pedunculated latissimus dorsi flap, and both patients recovered well.

Staple-Line Reinforcement of the Duodenal Stump With Intracorporeal Lembert's Sutures in Laparoscopic Distal Gastrectomy With Roux-en-Y Reconstruction for Gastric Cancer.

PURPOSE: We report a duodenal stump reinforcement procedure in laparoscopic distal gastrectomy with Roux-en-Y reconstruction. METHODS: We retrospectively reviewed the data of 223 patients who underwent laparoscopic distal gastrectomy with Roux-en-Y reconstruction for gastric cancer. We compared 2 groups: group NR (not reinforced, n=102, June 2009 to December 2011) when we did not perform reinforcement of the duodenal stump, and group R (reinforced, n=121, January 2012 to July 2014) when we did the reinforcement. The duodenum was divided with an endoscopic linear stapler. In group R, the duodenal staple line was reinforced by hand-sewn Lembert's sutures. RESULTS: There were no significant differences between group NR and R in patients' characteristics. Duodenal stump leakage occurred in 2 patients in group NR (2.0%). By contrast, in R group, no patients had duodenal stump leakage or fistula. CONCLUSIONS: Duodenal stump leakage can be avoided by using reinforcement with Lembert's sutures.

[A Case of Intra-Abdominal Desmoid Tumor with Abacterial Peritonitis].

A woman in her 50s visited our hospital in February 2015 with a complaint of dull abdominal pain in the right lower quadrant. She had a medical history of appendectomy for appendicitis in her 20s. Computed tomography(CT)revealed a tumor 90 mm in diameter near the ileocecum. Elective surgery was planned under the suspicion of gastrointestinal tumor, malignant lymphoma, or ileal cancer. She was emergently hospitalized 1 day earlier than scheduled because of high fever and severe abdominal pain. CT revealed that the tumor had increased to 120 mm in diameter without free air. Her white blood cell count was not elevated, and her symptoms improved readily with medical treatment. Thus, we performed the operation as scheduled. A tumor with a dark red recess on the surface had invaded the transverse colon intraoperatively, and a small amount of purulent ascites was present at the pouch of Douglas. We performed ileocecal resection with partial transverse colectomy. Histopathological examination led to the diagnosis of desmoid tumor in the mesentery of the terminal ileum. The surgical margins were negative for tumor cells. The tumor surface around the recess showed peritonitis, and the ascites showed no bacteria or tumor cells. The patient had been doing well without recurrence after discharge. Some cases of desmoid tumor with peritonitis have been reported, but most were caused by tumor penetration into the intestinal tract. We report herein a rare case of intra-abdominal desmoid tumor with abacterial peritonitis.