Incidental finding of Psuedomyxoma Peritonei in Malignant Peripheral Nerve Sheath Tumour.

Psuedomyxoma peritonei is an infrequent clinical entity characterised by intraperitoneal mucinous/gelatinous ascites produced by the cancerous cells. It has been associated with gastrointestinal, gynaecological, lung and breast tumours. It is commonly asymptomatic and is most often detected incidentally on abdominopelvic imaging or laparoscopy. Higher histological grade of the tumour shows increased metabolic activity on 18F-Fluorodeoxyglucose (FDG) positron-emission tomography (PET) computed tomography (CT). It has been rarely reported in patients with sarcoma. We hereby present an interesting case of incidentally diagnosed pseudomyxoma peritonei on 18FDG PET-CT scan of a patient with soft tissue sarcoma of peripheral nerve sheath.

Bland-Altman agreement analysis between CT predicted and surgical peritoneal cancer index in pseudomyxoma peritonei of appendiceal origin.

Peritoneal cancer index (PCI) is the surgical variable most commonly used to quantify the extent of peritoneal metastases for pseudomyxoma peritonei (PMP) patients. The present study aimed to investigate the agreement between CT predicted and surgical PCI by the Bland-Altman method for PMP of appendiceal origin. A total of 167 PMP patients of appendiceal origin were included between 2016 and 2021. Bland-Altman analysis was performed for both total PCI and selected PCI (regions 2 + 9-12). After the Bland-Altman plot was drawn, the mean bias and its 95% limit of agreements (LoAs) was quantified. Besides, the correlation coefficients between CT-PCI and surgical PCI were also been calculated. The Bland-Altman plot showed the mean bias ± SD between total CT-PCI and surgical PCI as 0.431 ± 3.005, with the LoAs from - 5.459 to 6.321. There were nine points of difference in total PCI exceeded the 95% LoAs, with the rate of 5.39% (9/167). As for selected CT-PCI, Bland-Altman plot showed the mean bias ± SD between selected CT-PCI and surgical PCI as - 0.287 ± 1.955, with the LoAs from - 4.118 to 3.544. There were ten points of difference in selected PCI exceeded the 95% LoAs, with the rate of 5.99% (10/167). The Spearman's rank correlation coefficient between total CT-PCI and surgical PCI was 0.911, P < 0.001, as for selected CT-PCI and surgical PCI, the coefficient was 0.909, P < 0.001. Although there was a strong correlation for both total and selected CT-PCI with surgical PCI, however, the agreement is still not good in Bland-Altman analysis, which suggested that CT-PCI cannot predict surgical PCI accurately even in professional PMP treatment centers. In brief explanation, CT makes it difficult to distinguish the borderline between tumor tissue and mucus and to detect tumor lesions in the small intestine regions, which caused overestimation or underestimation by CT-PCI. In the future, a multiple linear regression model based on CT-PCI might accurately predict surgical PCI preoperatively.

Ultrasound-guided day-case wide-bore percutaneous mucin aspiration in advanced pseudomyxoma peritonei.

AIM: To evaluate percutaneous ultrasound-guided day-case mucin aspiration in advanced pseudomyxoma peritonei (PMP) using a wide-bore drain with regards to its safety and efficacy. MATERIALS AND METHODS: All patients who underwent percutaneous mucin aspiration for PMP between 2019-2021 at a single national peritoneal tumour service were included in this study. Under local anaesthesia, a suction-enabled 28-32 F catheter was used for drainage following wire-guided track dilatation. The volume drained and difference in abdominal girth pre- and post-procedure were measured. Patients graded difficulty in breathing and abdominal discomfort pre- and post-procedure. Histology reports were reviewed. RESULTS: Sixteen patients received 56 percutaneous mucin aspirations between 2019-2021. The aetiology was a low-grade appendiceal mucinous neoplasm (LAMN) in 50% of patients. The mean amount of mucin drained was 7,320 ± 3,000ml (range 300-13,500 ml). The mean reduction in abdominal girth post-procedure was 12.2 ± 5 cm (range 0-27 cm). Only grade 1 complications were observed. CONCLUSION: Percutaneous ultrasound-guided day-case aspiration of mucin for advanced and recurrent PMP using a wide-bore drain is a safe and effective procedure. It may be used in the palliative setting or as a bridge to surgery in the very symptomatic patient or if there is a reversible contraindication to surgery.

Combined ultrasonography and CT for prognosis and predicting clinical outcomes of patients with pseudomyxoma peritonei.

OBJECTIVES: This study aimed to identify the diagnostic accuracy of combined ultrasonography (US) and computed tomography (CT) in evaluating the tumor burden of pseudomyxoma peritonei (PMP). Besides, we assessed the ability of this combination to predict the likelihood of complete resection. METHODS: This retrospective study involved 504 patients diagnosed with PMP and scheduled for cytoreduction surgery. We compared tumor burden-quantified as peritoneal cancer index (PCI) by preoperative US and CT (US-CT-PCI)-with surgical findings. Next, we assessed the prognostic value of US-CT PCI and imaging features in determining the completeness of cytoreduction (CCR) score using multivariate analysis. RESULTS: US-CT PCI demonstrated a high PCI evaluation accuracy under moderate tumor burden. Higher US-CT PCI could predict incomplete resection. In addition, we identified imaging features such as mesenteric involvement as an independent predictor of incomplete resection (hazard ratio (HR) = 2.006; p = 0.007). CONCLUSIONS: US-CT PCI allowed us to predict the completeness of cytoreductive surgery in patients with PMP. Moreover, the combined US and CT imaging detected several features indicating incomplete cytoreduction. KEY POINTS: • Ultrasonography (US) can act as a complementary diagnostic modality in peritoneal cancer index (PCI) evaluation by combining CT in the small bowel area and US in the abdominal area. • A modified peritoneal cancer index (US-CT PCI) helps preoperatively evaluate tumor burden with high accuracy and allows to predict incomplete resection. • US-CT PCI of 20 or above and the involvement of particular structures such as mesentery, independently indicate incomplete resection.

Culture and Imaging of Ex Vivo Organotypic Pseudomyxoma Peritonei Tumor Slices from Resected Human Tumor Specimens.

Pseudomyxoma peritonei (PMP) is a rare condition that results from the dissemination of a mucinous primary tumor and the resultant accumulation of mucin-secreting tumor cells in the peritoneal cavity. PMP can arise from various types of cancers, including appendiceal, ovarian, and colorectal, though appendiceal neoplasms are by far the most common etiology. PMP is challenging to study due to its (1) rarity, (2) limited murine models, and (3) mucinous, acellular histology. The method presented here allows real-time visualization and interrogation of these tumor types using patient-derived ex vivo organotypic slices in a preparation where the tumor microenvironment (TME) remains intact. In this protocol, we first describe the preparation of tumor slices using a vibratome and subsequent long-term culture. Second, we describe confocal imaging of tumor slices and how to monitor functional readouts of viability, calcium imaging, and local proliferation. In short, slices are loaded with imaging dyes and are placed in an imaging chamber that can be mounted onto a confocal microscope. Time-lapse videos and confocal images are used to assess the initial viability and cellular functionality. This procedure also explores translational cellular movement, and paracrine signaling interactions in the TME. Lastly, we describe a dissociation protocol for tumor slices to be used for flow cytometry analysis. Quantitative flow cytometry analysis can be used for bench-to-bedside therapeutic testing to determine changes occurring within the immune landscape and epithelial cell content.

Pleural decortication and hyperthermic intrathoracic chemotherapy for pseudomyxoma.

Aim: Pleural dissemination of pseudomyxoma peritonei (PMP) is an extremely rare diagnosis, for which no standard therapy is available.Methods: We describe the successful treatment of a 67-year-old male diagnosed with left-sided intrapleural dissemination of PMP (low-grade appendiceal mucinous neoplasm), 2 years after treatment of abdominal PMP with cytoreductive surgery (CRS) and hyperthermic intra-peritoneal chemotherapy. Treatment consisted of extended pleural decortication (ePD) and oxaliplatin-based hyperthermic intrathoracic chemotherapy (HITHOC). The patient is doing well without complications or signs of recurrence, 26 months after thoracic surgery.Conclusion: ePD in combination with HITHOC is a valuable treatment for thoracic PMP.

Radiomics analysis based on CT's greater omental caking for predicting pathological grading of pseudomyxoma peritonei.

The objective of this study was to predict the preoperative pathological grading and survival period of Pseudomyxoma peritonei (PMP) by establishing models, including a radiomics model with greater omental caking as the imaging observation index, a clinical model including clinical indexes, and a combined model of these two. A total of 88 PMP patients were selected. Clinical data of patients, including age, sex, preoperative serum tumor markers [CEA, CA125, and CA199], survival time, and preoperative computed tomography (CT) images were analyzed. Three models (clinical model, radiomics model and combined model) were used to predict PMP pathological grading. The models' diagnostic efficiency was compared and analyzed by building the receiver operating characteristic (ROC) curve. Simultaneously, the impact of PMP's different pathological grades was evaluated. The results showed that the radiomics model based on the CT's greater omental caking, an area under the ROC curve ([AUC] = 0.878), and the combined model (AUC = 0.899) had diagnostic power for determining PMP pathological grading. The imaging radiomics model based on CT greater omental caking can be used to predict PMP pathological grading, which is important in the treatment selection method and prognosis assessment.

Diagnostic performance of positron emission tomography in the staging of pseudomyxoma peritonei.

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare clinical entity, commonly derived from a mucin-producing tumour of the appendix. International consensus is unclear on the role of positron emission tomography (PET) in preoperative staging. This study aimed to assess the ability of preoperative PET in predicting the histological grade of PMP. METHODS: All patients scheduled for cytoreductive surgery (CRS) +/- hyperthermic intraperitoneal chemotherapy (HIPEC) for PMP who underwent preoperative PET at a single centre between June 2007 and June 2020 were included. A nuclear medicine physician, blinded to patient outcomes, retrospectively reviewed imaging studies to assess for maximum tumour standardised uptake value (SUV) to mean liver SUV ratio (SUVTLR) and maximum porta hepatis SUV to mean liver SUV ratio (SUVPLR). RESULTS: Between April 2007 and December 2020, a total of 204 patients underwent surgical intervention for PMP. Of these, 124 (60.8%) met the inclusion criteria. Median peritoneal carcinomatosis index for the entire cohort was 9 and complete cytoreduction (CC0/1) was achieved in 109 (88%) patients. Patients with high-grade PMP were more likely to have diffuse peritoneal disease (p < 0.001) and higher SUVTLR (p<0.001). The area under the ROC curve (AUC) of SUVTLR in predicting high-grade pathology was 71% (p = 0.003). Patients with a SUVTLR ≤ 0.78 had improved disease-free survival (p = 0.042). CONCLUSION: Preoperative PET showed positive correlation with high-grade PMP and acceptable sensitivity and specificity as a diagnostic tool. PET should be considered a useful adjunct to standard imaging for predicting histological grade in the staging of patients with PMP.

Peritoneal disease: key imaging findings that help in the differential diagnosis.

The peritoneum is a unique serosal membrane, which can be the site of primary tumors and, more commonly, secondary pathologic processes. Peritoneal carcinomatosis is the most common malignant condition to affect the peritoneal cavity, and the radiologist plays an important role in making the diagnosis and assessing the extent of disease, especially in sites that may hinder surgery. In this review, we address the role of the radiologist in the setting of peritoneal pathology, focusing on peritoneal carcinomatosis as this is the predominant malignant process, followed by revising typical imaging findings that can guide the differential diagnosis.We review the most frequent primary and secondary peritoneal tumor and tumor-like lesions, proposing a systemic approach based on clinical history and morphological appearance, namely distinguishing predominantly cystic from solid lesions, both solitary and multiple.

Case 295: Pseudomyxoma from Mucinous Adenocarcinoma of the Appendix Extending from the Retroperitoneum into the Thigh.

History A 57-year-old man with no remarkable past medical history presented to an outside institution with painless swelling in his right thigh of 6 months duration. He denied any trauma to the site. At that time, physical examination demonstrated swelling in his right upper thigh. All other work-up, including complete blood count and chest radiography, yielded negative results. The initial diagnosis was lymphangioma of the thigh. He continued to experience worsening swelling in his right upper thigh with no other symptoms over the next year. He was referred to our facility, where he underwent US evaluation of the thigh lesion, an MRI scan encompassing the entire extent of his thigh lesion, and a CT scan of his abdomen and pelvis.

[Clinicopathologic characteristics of appendiceal mucinous tumor misdiagnosed as gynecological neoplasms].

Objective: To explore the clinicopathologic features and prognosis of female appendiceal mucinous tumor misdiagnosed as gynecological neoplasm. Methods: The clinical data of 12 cases of suspected gynecological neoplasm but confirmed as appendiceal mucinous tumor by operation and pathology in Beijing Obstetrics and Gynecology Hospital hospital from 2010 to 2019 were collected. The clinicopathologic features, treatment and prognosis of these patients were analyzed. Results: The median age of 12 patients was 58 years old and the clinical manifestations were atypical, including 5 cases with gastrointestinal symptoms, 6 cases with touched lesion in the right adnexal area, 3 cases with pseudomyxoma of peritonei, and 4 cases with increased serological tumor markers and ascites. Before operation, ultrasonic diagnosis showed cystic or cystic-solid mass in the right adnexal region in all cases. Pelvic and abdominal enhanced CT and/or enhanced MRI were performed in 5 cases. Two cases indicated possible origin of appendix and 1 case indicated lymphatic cystic tumor. Laparoscopic or laparotomy exploration was performed in all patients, during the operation 7 cases were performed appendectomy, 4 cases were performed tumor cell reduction and 1 case was treated in another hospital after laparotomy exploration. Eleven cases were diagnosed as low-grade appendiceal mucinous tumor and 1 case as appendiceal mucinous adenocarcinoma by postoperative pathology. Among the 11 patients with low-grade appendiceal mucinous tumor, 9 cases had no recurrence, 1 case lost follow-up, 1 case died of breast cancer and 1 case died 18 months after the operation. Conclusions: Gynecologists should improve their ability to differentiate appendiceal mucinous tumor from gynecological neoplasm. They can include ultrasonic diagnosis and CT scanning into their preoperative physical examination to improve their examination ability, and strive for specialist or surgical treatment to achieve the best result.

Pseudomyxoma Peritonei - A Case Report.

A 53-year-old lady presented with post-menopausal bleeding (spotting) for two days and abdominal pain for three months. CT scan revealed bilateral adnexal mass and ascites; and CEA and CA19.9 was raised. Histopathology of the resected tissues revealed mucinous carcinoma of bilateral ovaries and colon with omental metastasis. Generally, pseudomyxoma peritonei arises from primary ovarian or appendiceal adenomas or adenocarcinomas. Keywords: Adenocarcinomas; ascites; metastases; mucinous carcinoma; pseudomyxoma peritonei.

Peritoneal MRI in patients undergoing cytoreductive surgery and HIPEC: History, clinical applications, and implementation.

MR imaging provides considerable advantages in the evaluation of patients with peritoneal metastases. A standardized peritoneal MRI protocol, including diffusion-weighted and gadolinium-enhanced sequences, allows an efficient exploration of small peritoneal tumors that are often missed on other imaging tests. In experienced hands, a dedicated reading allows producing a quantitative and qualitative evaluation of lesional localization to better assist surgeons in the selection of candidates for curative surgery by evaluating the possibility of complete resection, and to plan the surgical procedure. Based on a close collaboration between oncologic surgeon and radiologist, MRI provides a powerful tool for accurate preoperative imaging in patients being considered for curative surgery but also in their surveillance to detect an early recurrence.

Mucinous ascites secondary to peritoneal pseudomyxoma of an uncertain origin.

Peritoneal pseudomyxoma (PP) is a rare malignant tumor, which is characterized by the presence of mucinous ascites. Abdominal ultrasound as the first diagnostic method of this entity allows the visualization of ascites on the one hand and its analysis through a diagnostic paracentesis on the other.

Primary low-grade mucinous adenocarcinoma spleen resulting in Pseudomyxoma peritonei: A case report.

A 61-year-old man presented with complaints of abdominal pain, loss of weight, and splenomegaly since past 6 months. On computed tomography, the spleen was totally replaced by multiloculated cysts and splenectomy was performed. Pathological examination revealed a low-grade mucinous adenocarcinoma. Postoperative PET scan was negative, and in the absence of a primary tumor elsewhere, we considered this tumor to be primary in the spleen, and it was presumed that the tumor arose from invaginated capsular mesothelium of the spleen.

Pseudomyxoma peritonei: visceral scalloping on CT is a predictor of recurrence after complete cytoreductive surgery.

OBJECTIVES: Pseudomyxoma peritonei (PMP) is characterized by peritoneal dissemination of gelatinous ascites following rupture of a mucinous tumor. Treatment by cytoreductive surgery (CRS) has improved its prognosis. Although visceral scalloping, notably liver scalloping, on computed tomography (CT) is a typical feature of PMP, its prognostic value remains unknown. We aimed to investigate the efficacy of liver scalloping in predicting recurrence in PMP patients. METHODS: Among 159 consecutive patients with PMP who had contrast-enhanced CT between September 2012 and December 2018, 64 treatment-naïve patients who subsequently underwent CRS with complete resection (i.e., completeness of cytoreduction score (CC)-0 or CC-1), were included in analysis. Presence of liver scalloping and maximum thickness of mucin deposition at the liver surface were evaluated on CT. Disease-free survival (DFS) was determined based on the combination of postoperative CT features and tumor marker values. RESULTS: Median follow-up was 24.3 months. CT revealed liver scalloping in 40/64 (63.4%) patients. Kaplan-Meier analysis showed significantly shorter DFS in patients with scalloping than in those without (p = 0.001; hazard ratio, 4.3). In patients with scalloping, greater mucin deposition (thickness ≥ 20 mm) significantly correlated with poorer DFS (p = 0.042). In multivariate Cox proportional hazards regression including CC status, pathologic type, and tumor markers, the presence of scalloping independently and significantly correlated with DFS (p = 0.031). CONCLUSIONS: Liver scalloping was an independent predictor even after adjusting for clinical covariates. The presence of liver scalloping can lead to a high recurrence rate after CRS. KEY POINTS: • The presence of liver scalloping is a prognostic factor independent of histological grade and tumor markers. • Greater mucin deposition (thickness ≥ 20 mm at the liver surface) is associated with higher recurrence rates in patients with liver scalloping.

Value of preoperative ultrasound in evaluating the peritoneal cancer index of pseudomyxoma peritonei.

PURPOSE: This study aimed to explore the value of preoperative ultrasonography (US) in evaluating the peritoneal cancer index (PCI) of pseudomyxoma peritonei (PMP). METHODS: An ultrasound examination was performed on 59 patients with PMP before surgery, and the ultrasound PCI was evaluated. The accuracy of ultrasound PCI score was evaluated with the surgical PCI score as the gold standard. RESULTS: The preoperative ultrasound PCI was compared with the surgical PCI. The Spearman correlation coefficient of the total PCI score was 0.608 (P < 0.05). The difference in the Spearman correlation coefficient between the preoperative ultrasound PCI and the surgical PCI in areas 0-7 was statistically significant. (1) Among them, the total score and the correlation between 0-3 and 6 were higher. (2) Compared with the surgical PCI, overestimation (> 20%) was concentrated mainly in areas 2 and 4-8 for 2 points, and underestimation (< 20%) was concentrated mainly in areas 1, 3, 4, and 8 for 3 points. (3) The sensitivity and specificity of preoperative ultrasound for predicting the presence or absence of lesions were 85.7% and 50.0%, respectively. The sensitivity of LS 1, LS 2, and LS 3 was 31.7%, 48.2%, and 71.0%, respectively, and the specificity was 44.8%, 55.3%, and 58.8%, respectively. CONCLUSION: The ultrasound examination can be used to score the preoperative PCI, judge the severity, and predict the prognosis in patients with PMP.

Ruptured primary mucinous cystadenoma of spleen leading to mucinous ascites.

Mucinous cystadenoma are rare benign mucin-producing tumours. Primary mucinous neoplasms most commonly involve ovary, pancreas or appendix. They may rupture to produce mucous ascites/pseudomyxoma peritonei. We are describing a 51-year-old man who presented to us with symptomatic gallstone disease but during preoperative ultrasound was found to have cystic lesions in spleen with free fluid in the abdomen. Splenectomy and drainage of mucin were done. Histopathology was done and a final diagnosis of primary mucinous cystadenoma of spleen with mucinous ascites was made.