Human peritoneal fluid exerts ovulation- and nonovulation-sourced oncogenic activities on transforming fallopian tube epithelial cells.

Secretory cells in the fallopian tube fimbria epithelium (FTE) are regarded as the main cells of origin of ovarian high-grade serous carcinoma (HGSC). Ovulation is the main cause of FTE oncogenesis, which proceeds through a sequence of TP53 mutations, chromosomal instability due to Rb/cyclin E aberration, in situ carcinoma (STIC), and metastasis to the ovary and peritoneum (metastatic HGSC). Previously, we have identified multiple oncogenic activities of the ovulatory follicular fluid (FF), which exerts the full spectrum of transforming activity on FTE cells at different stages of transformation. After ovulation, the FF is transfused into the peritoneal fluid (PF), in which the FTE constantly bathes. We wondered whether PF exerts the same spectrum of oncogenic activities as done by FF and whether these activities are derived from FF. By using a panel of FTE cell lines with p53 mutation (FT282-V), p53/CCNE1 aberrations (FT282-CCNE1), and p53/Rb aberrations plus spontaneous transformation, and peritoneal metastasis (FEXT2), we analyzed the changes of different transformation phenotypes after treating with FF and PF collected before or after ovulation. Similar to effects exhibited by FF, we found that, to a lesser extent, PF promoted anchorage-independent growth (AIG), migration, anoikis resistance, and peritoneal attachment in transforming FTE cells. The more transformed cells were typically more affected. Among the transforming activities exhibited by PF treatment, AIG, Matrigel invasion, and peritoneal attachment growth were higher with luteal-phase PF treatment than with the proliferative-phase PF treatment, suggesting an ovulation source. In contrast, changes in anoikis resistance and migration activities were similar in response to treatment with PF collected before and after ovulation, suggesting an ovulation-independent source. The overall transforming activity of luteal-phase PF was verified in an i.p. co-injection xenograft mouse model. Co-injection of Luc-FEXT2 cells with either FF or luteal-phase PF supported early peritoneal implantation, whereas co-injection with follicular-phase PF did not. This study, for the first time, demonstrates that PF from ovulating women can promote different oncogenic phenotypes in FTE cells at different stages of malignant transformation. Most of these activities, other than anoikis resistance and cell migration, are sourced from ovulation.

Peritoneal Seeding after Gastric Perforation during Endoscopic Submucosal Dissection for Gastric Cancer.

BACKGROUND/AIMS: Since the risk of cancer cells seeding the peritoneum after perforation during endoscopic submucosal dissection (ESD) is unclear, we retrospectively examined peritoneal relapse after gastric perforation during ESD for gastric cancer at a single institution. METHODS: Of 876 patients who underwent ESD for early gastric cancer between January 2002 and December 2015, 22 patients (2.5%) experienced gastric perforation during ESD at the Osaka National Hospital in Osaka, Japan. Clinical data from these 22 patients were reviewed for information on pathology, clinical course, and evidence of peritoneal dissemination. RESULTS: Patients were followed for a median of 55 (range 2-108) months. Two patients had peritoneal seeding following perforation during ESD. Multivariate analysis to explore the influence of clinical factors on the peritoneal seeding revealed that an intra-abdominal fluid collection on the CT imaging just after ESD, tumor location at the upper lesion of stomach, and pathologically marginal invasion were independently associated with an incidence of peritoneal relapse. CONCLUSION: Although rare, we should recognize the possibility of cancer cells seeding the peritoneum after perforation during gastric ESD.

Is EUS-FNA of solid-pseudopapillary neoplasms of the pancreas as a preoperative procedure really necessary and free of acceptable risks?

BACKGROUND: Solid-pseudopapillary neoplasms (SPNs) of the pancreas are infrequent tumors since, as of 2014, only 2744 patients have been described. Its rarity, unclear histogenesis, pleomorphic aspect on radiology (cystic, solid or mixed) and unpredictable biological behavior with an insidious high-grade malignant potential make SPN difficult to recognize preoperatively even in its target patient population which is predominantly composed of young women (about 87% of cases). METHODS: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) showed to improve the preoperative diagnostic yield for this tumor and obviate the risks formerly given by percutaneous biopsy. RESULTS: In light of our experience, such a procedure could not be so innocuous as generally acknowledged. CONCLUSION: We report the first case of rupture of pancreatic SPN following EUS-FNA and entertain both the actual and potential complications ensuing from this type of mishap.

[18F]FDOPA PET/CT in Solid Pseudopapillary Tumor of the Pancreas: a Recurred Tumor Mimicking Splenosis.

Solid pseudopapillary tumor (SPT) of the pancreas is a neoplasm with low malignant potential. It is often challenging to diagnose SPT due to its nonspecific clinical and radiological features, and [18F]FDOPA is effective in diagnosing SPT, particularly in differentiating SPT from benign conditions such as splenosis. A 55-year-old woman underwent distal pancreatectomy and splenectomy for histologically confirmed SPT. She was also initially diagnosed with splenosis. During follow-up, sizes of multiple nodular lesions were increased, raising the possibility of peritoneal seeding of SPT. For diagnosis, a spleen scan and SPECT/CT were performed using 99mTc-labeled damaged red blood cells, which showed no uptake in the peritoneal nodules. Subsequent [18F]FDOPA PET/CT revealed [18F]FDOPA-avidity of the nodules. The patient underwent tumor resection surgery, and the nodules were pathologically confirmed as SPT.

Peritoneal seeding of embolic beads after uterine artery embolization.

Background: Incidental identification of peritoneal nodules during laparoscopy may present a diagnostic dilemma. The differential diagnosis includes a variety of benign and malignant entities such as peritoneal carcinomatosis. Case: A 44-year-old G2P2 woman presented with recurrent menorrhagia and pelvic pain was found to have large uterine fibroids on imaging studies. Bilateral uterine artery embolization was performed with complete devascularization of the fibroid. Seven years later, she presented with similar symptoms. Imaging studies demonstrated a vascular uterine lesion. A total laparoscopic hysterectomy with bilateral salpingectomy was performed with no complications. During surgery, vesicular peritoneal implants were incidentally identified posterior to the uterus between the uterosacral ligaments. Biopsy and pathologic analysis of these nodules confirmed that they contained foreign material consistent with embolization beads. Pathologic analysis of the uterus demonstrated an intramural uterine fibroid, and presence of embolization beads in cervix, myometrium and bilateral peritubal regions. Conclusion: Non-target peritoneal implantation of embolic beads after uterine artery embolization is a rare entity that can result in vesicular appearing nodules.

Risk prediction model of peritoneal seeding in advanced gastric cancer: A decision tool for diagnostic laparoscopy.

BACKGROUND: Selective diagnostic laparoscopy in gastric cancer patients at high risk of peritoneal metastasis is essential for optimal treatment planning. In this study available clinicopathologic factors predictive of peritoneal seeding in advanced gastric cancer (AGC) were identified, and this information was translated into a clinically useful tool. METHODS: Totally 2833 patients underwent surgery for AGC between 2003 and 2013. The study identified clinicopathologic factors associated with the risk of peritoneal seeding for constructing nomograms using a multivariate logistic regression model with backward elimination. A nomogram was constructed to generate a numerical value indicating risk. Accuracy was validated using bootstrapping and cross-validation. RESULTS: The proportion of seeding positive was 12.7% in females and 9.6% in males. Of 2833 patients who underwent surgery for AGC, 300 (10.6%) were intraoperatively identified with peritoneal seeding. Multivariate analysis revealed the following factors associated with peritoneal seeding: high American Society of Anesthesiologists score, fibrinogen, Borrmann type 3 or 4 tumors, the involvement of the middle, anterior, and greater curvature, cT3 or cT4cN1 or cN2 or cN3, cM1, and the presence of ascites or peritoneal thickening or plaque or a nodule on the peritoneal wall on computed tomography. The bootstrap analysis revealed a robust concordance between mean and final parameter estimates. The area under the ROC curve for the final model was 0.856 (95% CI, 0.835-0.877), which implies good performance. CONCLUSIONS: This nomogram provides effective risk estimates of peritoneal seeding from gastric cancer and can facilitate individualized decision-making regarding the selective use of diagnostic laparoscopy.

A case of successful surgical treatment for peritoneal seeding of hepatocellular carcinoma after radiotherapy and atezolizumab plus bevacizumab combination treatment.

Peritoneal seeding of hepatocellular carcinoma (HCC) is incurable and has poor prognosis. A 68-year-old man underwent surgical resection for a 3.5 cm single nodular HCC at the tip of segment 3 and transarterial chemoembolization for a 1.5 cm-sized recurrent HCC at the tip of segment 6. 3 months later, an increasing 1 cm pelvic nodule on the rectovesical pouch warranted radiotherapy. Although it stabilized, a new 2.7 cm-sized peritoneal nodule in the right upper quadrant (RUQ) omentum appeared 3.5 years after radiotherapy. Hence, omental mass and small bowel mesentery mass excision were performed. 3 years later, recurrent peritoneal metastases in the RUQ omentum and rectovesical pouch progressed. 33 cycles of atezolizumab and bevacizumab treatment elicited stable disease response. Finally, laparoscopic left pelvic peritonectomy was performed without tumor recurrence. Herein, we present a case of HCC with peritoneal seeding that was successfully treated with surgery after radiotherapy and systemic therapy, leading to complete remission.

Peritoneal Seeding Is More Common in Gastric Cancer Patients with FGFR2 Amplification or High Tumor Mutation Burden.

Fibroblast growth factor receptor-2 (FGFR2) gene alterations have been identified in solid tumors. FGFR2 amplification is found in 2−9% of gastric carcinomas. We hypothesized that FGFR2 could be associated with peritoneal seeding and studied 360 advanced gastric carcinoma patients; 222 (61.7%) were male, 246 (73.7%) had poorly differentiated histology, and 175 (48.6%) presented with peritoneal seeding. High tumor mutation burden (TMB) was observed in 44 (12.2%) patients, high microsatellite instability (MSI) was observed in 12 (3.33%) patients, ERBB2 amplification was observed in 44 (12.2%) patients, EBV positivity was observed in 10 (10/278; 3.6%) patients, and PD-L1 positivity was observed in 186 (186/264; 70.5%) cases. We found FGFR2 amplification in 26 (7.2%) patients, of which 12 (46.2%) were female and 22 (84.6%) had poorly differentiated histology. In these 26 cases, the copy number of FGFR2 amplification ranged from 3.7 to 274. Eighteen of them showed seeding, and this association was statistically significant (18/26, 69.2%; 157/334, 47%; p = 0.023). In addition, high TMB was significantly associated with seeding (p = 0.028; OR = 1.83). Poorly differentiated histology was significantly associated with seeding (p = 0.04) but not with FGFR2 amplification (p > 0.1). Seeding was frequent in gastric carcinoma patients with FGFR2 amplification, in patients with high TMB, or in those who were female. The subgroup of patients with FGFR2 amplification could be potential candidates for targeted therapeutic agents.

Foreign body granulomas mimic peritoneal dissemination caused by incarcerated femoral hernia perforation: A case report.

BACKGROUND: Foreign body granuloma (FBG) is a well-known type of granulomatous formation, and intraabdominal FBG (IFBG) is primarily caused by surgical residues. Multifocal IFBGs caused by gastrointestinal perforation is an extremely rare and interesting clinicopathological condition that resembles peritoneal dissemination. Here, we present a case of IFBGs mimicking peritoneal dissemination caused by bowel perforation and describe the value of intraoperative pathological examinations for rapid IFBG diagnosis. CASE SUMMARY: An 86-year-old woman with an incarcerated femoral hernia was admitted to the hospital and underwent operation. During the operation, the incarcerated ileum was perforated during repair due to hemorrhage necrosis, and a small volume of enteric fluid leaked from the perforation. The incarcerated ileum was resected, and the femoral hernia was repaired without mesh. Four months later, a second operation was performed for an umbilical incisional hernia. During the second operation, multiple small, white nodules were observed throughout the abdominal cavity, resembling peritoneal dissemination. The results of peritoneal washing cytology in Douglas' pouch and the examination of frozen nodule sections were compatible with IFBG diagnosis, and incisional hernia repair was performed. CONCLUSION: IFBGs can mimic malignancy. Intraoperative pathological examinations and operation history are valuable for the rapid diagnosis to avoid excessive treatments.

Splenosis Mimicking Peritoneal Seeding of Advanced Colon Cancer Can Be Identified by Spleen SPECT/CT and FDG PET/CT.

This case report demonstrates that Tc-99m labeled heat-damaged red blood cell single-photon emission computed tomography/computed tomography (spleen SPECT/CT) and F-18 fluorodeoxyglucose positron emission tomography/CT (FDG PET/CT) could noninvasively confirm splenosis mimicking peritoneal seeding of advanced sigmoid colon cancer with hepatic metastases, and played a crucial role in determining the treatment plan.

The efficiency of D1(+) lymphadenectomy in signet ring cell carcinoma: comparison of postoperative early and late outcomes between standard lymphadenectomy and D1(+) lymphadenectomy.

Signet ring cell carcinoma (SRCC) is a poorly cohesive subtype of gastric cancer. It is more aggressive than other types of gastric cancer. There is no special method for its treatment, but gastrectomy and lymphadenectomy is the standard approach. The aim of this study is to investigate postoperative outcomes of D1 lymphadenectomy and D1(+)lymphadenectomy in gastric SRCC.A total of 358 cases whohad a gastrectomy performed forthe diagnosis of gastric cancer between 2013 and 2019 in Ankara University Medical Faculty, Surgical Oncology Department were retrospectively investigated. In all, 128 of the cases had SRCC in the final pathology. We separated the cases into two types,D1 lymphadenectomy and D1(+) lymphadenectomy. The 5-year survival, early mortality, hospital mortality and postoperative complication rates were evaluated.There were 59 patients in the D1 group and 64 patients in the D1(+) group.Metastatic lymph node amount and therefore N stage was found to be significantly higher in the D1(+) group (p=0.00 and p=0.03, respectively). Postoperative chyle fistula was found to be significantly higher in the D1(+) group (p=0.003). There was no statistically significant difference between the groups with regard tomean survival (p=0.065);the 5-year mean survival was 21% in the D1 group and 7% in the D1(+) group. Present findings suggest that extended lymphadenectomy does not provide a benefit in cases of SRCC.

Anaplastic ependymoma metastases though a ventriculoperitoneal shunt.

Ependymomas are rare glial tumors that comprise 10% of intracranial pediatric malignancies. Primary central nervous system malignancies can rarely metastasize extracranially. When metastases occur, it usually does so in the setting of surgical manipulation of the central nervous system and can spread through the blood, lymph, or artificial means, for example, a ventriculoperitoneal shunt. We describe the presentation and progression of an 18-month-old boy diagnosed with an ependymoma. Initially managed with surgery, radiation, and ventriculoperitoneal shunt placement for symptomatic hydrocephalus, the tumor later recurred with drop metastasis to the thoracic spinal cord. The patient subsequently developed extensive metastases within the abdominal cavity, which were seeded through a ventriculoperitoneal shunt. We present a case of a rare complication of intra-abdominal tumor seeding and carcinomatosis from an intracranial ependymoma through a ventriculoperitoneal shunt. This is a rare presentation of a possible complication, which requires awareness of both surgeons and radiologists.

Differentiation of intra-abdominal desmoid tumor from peritoneal seeding based on CT and/or 18F-FDG PET-CT in patients with history of cancer surgery.

PURPOSE: To investigate differential imaging features of intra-abdominal desmoid tumors and peritoneal seeding in patients with history of cancer surgery. METHODS: Thirty-two patients who had a single pathologically proven intra-peritoneal lesion that developed after cancer surgery were enrolled between January 2000 and June 2019. There were 16 desmoid tumors and 16 peritoneal seeding lesions. Portal phase CT and/or 18F-FDG PET findings were analyzed by two radiologists in consensus for the following items: location, size, shape, margin, contour, homogeneity, necrosis, adjacent organ invasion, calcification, intra-lesional fat, peritoneal infiltration, mass effect, and degree of enhancement. Hounsfield units (HU) and maximum standardized uptake values (SUVmax) of the lesions were measured. Imaging findings were compared using the Chi square test, Fisher's exact test, and student t test. RESULTS: Desmoid tumors frequently showed well-defined margins (9/16) and smooth contours (12/16), whereas peritoneal seeding had ill-defined margins (13/16) and lobulated contours (11/16) (P = 0.028 and 0.013, respectively). Intra-lesional fat was found more frequently in desmoid tumors (7/16) than peritoneal seeding (1/16) (P = 0.014). Desmoid tumors showed iso-attenuation (13/16) compared to psoas muscle in portal phase, while peritoneal seeding depicted high attenuation (12/16) (P = 0.002). Mean HU was significantly lower in desmoid tumors (64.3) than peritoneal seeding lesions (95.1) (P = 0.001). However, the mean SUVmax of desmoid tumors (4.1) did not significantly differ from peritoneal seeding lesions (5.2) (P = 0.519). CONCLUSION: Several CT features including iso-attenuation in portal phase and presence of intra-lesional fat can be helpful in differentiating desmoid tumors from peritoneal seeding in patients with history of intra-abdominal cancer surgery.

Diffuse midline glioma metastasis to the peritoneal cavity via ventriculo-peritoneal shunt: Case report and review of literature.

Extraneural dissemination of primary intracranial tumours to the peritoneal cavity via ventriculoperitoneal shunts is rare, with medulloblastoma and germ-cell tumours most common and gliomas seldom implicated. This report is the first described case of a diffuse midline glioma H3 K27M-mutant disseminating to the peritoneal cavity via a shunt. A four-year-old female presented with a large solid-cystic lesion centred on the suprasellar cistern, histologically revealed to be diffuse midline glioma H3 K27M-mutant. The patient received multiple courses of radiotherapy to the primary lesion and metachronous spinal metastases, and underwent bilateral ventriculoperitoneal shunts. She presented fourteen months following diagnosis with acute hydrocephalus and massive ascites revealed to be due to histologically confirmed intra-abdominal glioma metastasis secondary to shunting. Bilateral ventriculoatrial shunts along with targeted abdominal radiotherapy and repeated ascitic drainage were performed. The patient died one month later. A literature review demonstrated that intra-abdominal glioma metastasis is an extremely rare complication of cerebrospinal fluid diversion predominantly affecting paediatric patients with high-grade lesions within the first year after diagnosis and portends poor prognosis. Predisposition to metastasis is likely associated with tumour proximity to cerebrospinal fluid spaces and tumour biology. Contraindicating shunting in the presence of an intracranial tumour cannot be endorsed but rather shunt-related metastasis should be an acknowledged risk, and not-to-be-forgotten presentation.

Long-term Clinical Outcomes and Risk of Peritoneal Seeding after Endoscopic Submucosal Dissection for Early Gastric Cancer: A Focus on Perforation during the Procedure.

Background/Aims: The risk of peritoneal seeding following perforation after endoscopic resection in patients with early gastric cancer is unclear. The purpose of this study was to investigate long-term clinical outcomes including peritoneal seeding and overall survival rate following gastric perforation during endoscopic submucosal dissection (ESD). Methods: Between January 2002 and March 2015, 556 patients were diagnosed with early gastric cancer and underwent ESD. Among them, 34 patients (6.1%) experienced gastric perforation during ESD. Clinicopathological data of these patients were reviewed to determine the clinical outcome and evidence of peritoneal seeding. Results: Among 34 patients with perforation, macroperforations occurred during ESD in 17 cases (50%), and microperforation was identified in the remaining 17 cases (50%). All patients except one who underwent emergency surgery due to severe panperitonitis were managed successfully by endoscopic clipping (n=27) or conservative medical treatment (n=6). No evidence of peritoneal seeding after perforation associated with ESD was found in our cohort. Cumulative survival rates did not differ between the perforation and non-perforation groups (p=0.691). Furthermore, mortality was not associated with perforation. In addition, multivariate analysis showed that tumor size and achievement of curative resection were related to cancer recurrence. Perforation was not associated with cancer recurrence and survival. Conclusions: Perforation associated with ESD does not lead to worse clinical outcomes such as peritoneal seeding or cumulative survival rate. Therefore, periodic follow-up might be possible if curative resection was achieved even if perforation occurred during ESD.

Advances in Intraluminal Exfoliative Cytology of Gastric Cancer: Oncologic Implication of the Sixth Metastatic Route (Metastasis VI).

Historically, analysis of intragastric exfoliative cytology (IEC) of gastric cancer (GC) was used with a diagnostic intent only. With the successful advent of endoscopic biopsy, the rate of detection of GC has improved worldwide and, as a consequence, IEC has been progressively abandoned. Today, however, there is a renewed interest in this field of research, as witnessed by several pertinent publications. As discussed in this review, in fact, currently the importance of analyzing IEC in patients with early and advanced GC seems to reside in its clinicopathological and prognostic significance. In fact, compared to non-sloughing tumors, GC exhibiting intragastric exfoliation was recently associated with an aggressive tumor phenotype (characterized by deeper infiltration of the gastric wall, lymph nodal or distant metastases, angiolymphatic and perineural invasion) and poorer prognosis. Adoption of IEC examination in routine practice might help identify patients at higher risk of developing local recurrence and peritoneal metastasis from early and advanced GC, optimizing their treatment and improving quality of life and life expectancy.

Glasgow Prognostic Score is superior to ECOG PS as a prognostic factor in patients with gastric cancer with peritoneal seeding.

The Glasgow Prognostic Score (GPS) has been shown to be associated with survival rates in patients with advanced cancer. The present study aimed to compare the GPS with the Eastern Cooperative Oncology Group Performance Status (ECOG PS) in patients with gastric cancer with peritoneal seeding. For the investigation, a total of 384 gastric patients with peritoneal metastasis were retrospectively analyzed. Patients with elevated C-reactive protein (CRP; >10 mg/l) and hypoalbuminemia (<35 mg/l) were assigned a score of 2. Patients were assigned a score of 1 if presenting with only one of these abnormalities, and a score of 0 if neither of these abnormalities were present. The clinicopathologic characteristics and clinical outcomes of patients with peritoneal seeding were analyzed. The results showed that the median overall survival (OS) of patients in the GPS 0 group was longer, compared with that in the GPS 1 and GPS 2 groups (15.50, vs. 10.07 and 7.97 months, respectively; P<0.001). No significant difference was found between the median OS of patients with a good performance status (ECOG <2) and those with a poor (ECOG ≥2) performance status (13.67, vs. 11.80 months; P=0.076). In the subgroup analysis, the median OS in the GPS 0 group was significantly longer, compared with that in the GPS 1 and GPS 2 groups, for the patients receiving palliative chemotherapy and patients without palliative chemotherapy. Multivariate survival analysis demonstrated that CA19-9, palliative gastrectomy, first-line chemotherapy and GPS were the prognostic factors predicting OS. In conclusion, the GPS was superior to the subjective assessment of ECOG PS as a prognostic factor in predicting the outcome of gastric cancer with peritoneal seeding.

Comparative proteomic analysis of human malignant ascitic fluids for the development of gastric cancer biomarkers.

OBJECTIVES: Malignant ascites is a sign of peritoneal seeding, which is one of the most frequent forms of incurable distant metastasis. Because the development of malignant ascites is associated with an extremely poor prognosis, determining whether it resulted from peritoneal seeding has critical clinical implications in diagnosis, choice of treatment, and active surveillance. At present, the molecular characterizations of malignant ascites are especially limited in case of gastric cancer. We aimed to identify malignant ascites-specific proteins that may contribute to the development of alternative methods for diagnosis and therapeutic monitoring and also increase our understanding of the pathophysiology of peritoneal seeding. DESIGN & METHODS: First, comprehensive proteomic strategies were employed to construct an in-depth proteome of ascitic fluids. Label-free quantitative proteomic analysis was subsequently performed to identify candidates that can differentiate between malignant ascitic fluilds of gastric cancer patients from benign ascitic fluids. Finally, two candidate proteins were verified by ELISA in 84 samples with gastric cancer or liver cirrhosis. RESULTS: Comprehensive proteome profiling resulted in the identification of 5347 ascites proteins. Using label-free quantification, we identified 299 proteins that were differentially expressed in ascitic fluids between liver cirrhosis and stage IV gastric cancer patients. In addition, we identified 645 proteins that were significantly expressed in ascitic fluids between liver cirrhosis and gastric cancer patients with peritoneal seeding. Finally, Gastriscin and Periostin that can distinguish malignant ascites from benign ascites were verified by ELISA. CONCLUSIONS: This study identified and verified protein markers that can distinguish malignant ascites with or without peritoneal seeding from benign ascites. Consequently, our results could be a significant resource for gastric cancer research and biomarker discovery in the diagnosis of malignant ascites.

New intra-abdominal mass after operation for colorectal cancer: desmoid tumor versus peritoneal seeding.

PURPOSE: To identify differential clinical and imaging findings between intra-abdominal desmoid tumors and peritoneal seeding that developed after surgery for colorectal cancer. METHODS: 8 patients (9 desmoid tumors) and 11 patients (13 peritoneal seeding masses) were enrolled in our retrospective study. Patients with three or more tumors were excluded. Clinical findings including location of initial tumors, type of surgery, T- and N-stages of initial tumors, time interval between initial surgery and development of intra-abdominal tumors, and level of carcinoembryonic antigen (CEA) were evaluated. Imaging findings of intra-abdominal tumors including size, number, growth rate, location, shape, homogeneity, relative enhancement, and maximum standardized uptake value were evaluated. The Mann-Whitney U test and Fisher's exact test were used to compare clinical and imaging findings between desmoid tumors and peritoneal seeding. RESULTS: In patients with a desmoid tumor, initial T-stage, initial N-stage, and level of CEA at the time of surgery for intra-abdominal tumor were lower than in patients with peritoneal seeding (p = 0.027, p = 0.033, and p = 0.017). The desmoid tumors were frequently located in the small bowel mesentery (p = 0.018) and were larger at detection (p = 0.041). Round or ovoid shapes on CT images were more frequently observed with the desmoid tumors (p = 0.035). CONCLUSIONS: Stage of colorectal cancer, CEA level, and location, size, and shape of new intra-abdominal tumors can be helpful for differentiating between intra-abdominal desmoid tumors and peritoneal seeding in patients with a history of colorectal cancer surgery.

Detection of needle tract implantation and peritoneal seeding after radiofrequency ablation using intraoperative near-infrared fluorescence system for recurrent hepatocellular carcinoma: a case report.

BACKGROUND: Radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is already fully established worldwide. Needle tract implantation and peritoneal seeding occasionally occur by RFA, and the prognosis of these cases is thought to be poor. In this study, intraoperative real-time near-infrared fluorescence (NIRF) system by indocyanine green (ICG) incidentally detected both needle tract implantation and peritoneal seeding. As the utility of this system for identification of implanted and disseminated lesions after RFA for HCC has not been widely reported, we report a case of successful detection by real-time ICG-NIRF imaging and subsequent resection. CASE PRESENTATION: A 76-year-old man originally underwent medial sectionectomy for HCC in 2009. When repeated intrahepatic recurrence occurred, he underwent RFA and transcatheter arterial chemoembolization (TACE) for recurrent HCC twice at segment III and once at segment IV. In 2013, the second hepatectomy for recurrent HCC at segment VIII was performed. In 2016, he had recurrent HCC at segment III around a previous RFA and TACE scar; therefore, left lateral sectionectomy was planned. ICG-NIRF system was used to observe a main intrahepatic metastasis at segment III and to search for other tumors in the remnant liver. Although there was no signal on the surface of the remnant liver, tiny signals were observed in the abdominal wall and greater omentum. These tumors were on the needle tract of the previous RFA; both lesions, therefore, were resected. These tumors were pathologically proven to be HCC metastases. The patient has had no recurrence 14 months after the last hepatectomy. CONCLUSIONS: ICG-NIRF system might be helpful in the detection of not only intrahepatic lesions but also needle tract implantations or peritoneal seeding. RFA should be avoided in patients with high risk of needle tract implantation and peritoneal seeding.