The many faces of pseudomyxoma peritonei: a radiological review based on 30 cases

Imaging in Hyperthermic Intraperitoneal Chemotherapy

Hyperthermic intraperitoneal chemotherapy (HIPEC) combined with cytoreductive surgery (CRS) (CRS-HIPEC) has revolutionized the management of peritoneal malignancies, pivoting from a palliative care approach to a treatment strategy tailored to improve overall survival. This procedure is based on the principle that local instillation of heated chemotherapeutic agents augments their cytotoxic effects, which target and eradicate microscopic disease. Imaging is integral to the management of patients undergoing HIPEC, having multiple roles that range from patient selection, preoperative assessment, and determining treatment effectiveness to postprocedural surveillance. Various imaging modalities can be used for radiologic assessment and include CT, dual-energy CT, MRI, fluorine 18-fluorodeoxyglucose PET/CT, and PET/MRI. A crucial step in assessing the feasibility of CRS-HIPEC is estimation of the peritoneal carcinomatosis index, which enables one to determine the total peritoneal disease burden and is essential for effective multidisciplinary management. Following HIPEC, the completeness of cytoreduction score and residual disease score provide a robust framework for assessing treatment efficacy and strategically guiding subsequent management and surveillance protocols. Imaging facilitates accurate evaluation of complications, as well as early recognition of residual or recurrent peritoneal disease. The authors provide a comprehensive overview of HIPEC therapy, focusing on the role of imaging in the management of patients with peritoneal malignancies, delving into the nuances of this procedure, and discussing crucial aspects related to patient selection, surgical complexity, and prediction of outcomes. ©RSNA, 2025 See the invited commentary by Wasif in this issue.

The Peritoneum: Anatomy, Pathologic Findings, and Patterns of Disease Spread

Disease spread in the abdomen and pelvis generally occurs in a predictable pattern in relation to anatomic landmarks and fascial planes. Anatomically, the abdominopelvic cavity is subdivided into several smaller spaces or compartments by key ligaments and fascial planes. The abdominal cavity has been traditionally divided into peritoneal, retroperitoneal, and pelvic extraperitoneal spaces. Recently, more clinically relevant classifications have evolved. Many pathologic conditions affect the abdominal cavity, including traumatic, inflammatory, infectious, and neoplastic processes. These abnormalities can extend beyond their sites of origin through various pathways. Identifying the origin of a disease process is the first step in formulating a differential diagnosis and ultimately reaching a final diagnosis. Pathologic conditions differ in terms of pathways of disease spread. For example, simple fluid tracks along fascial planes, respecting anatomic boundaries, while fluid from acute necrotizing pancreatitis can destroy fascial planes, resulting in transfascial spread without regard for anatomic landmarks. Furthermore, neoplastic processes can spread through multiple pathways, with a propensity for spread to noncontiguous sites. When the origin of a disease process is not readily apparent, recognizing the spread pattern can allow the radiologist to work backward and ultimately arrive at the site or source of pathogenesis. As such, a cohesive understanding of the peritoneal anatomy, the typical organ or site of origin for a disease process, and the corresponding pattern of disease spread is critical not only for initial diagnosis but also for establishing a road map for staging, anticipating further disease spread, guiding search patterns and report checklists, determining prognosis, and tailoring appropriate follow-up imaging studies. ©RSNA, 2024 Supplemental material is available for this article.

A Review of Pseudomyxoma Peritonei: Insights Into Diagnosis, Management, and Prognosis

Pseudomyxoma peritonei (PMP) is a rare and complex clinical syndrome characterized by the accumulation of mucinous ascites within the peritoneal cavity, typically associated with mucinous tumours of appendiceal origin. Despite its rarity, PMP poses significant challenges in diagnosis and management due to its indolent yet locally aggressive nature. This comprehensive review provides insights into the diagnosis, management, and prognosis of PMP, synthesizing current evidence and emerging trends in the field. Challenges and opportunities in PMP management are discussed, along with recommendations for clinical practice emphasizing the importance of a multidisciplinary approach and specialized care. Despite ongoing challenges, advances in surgical techniques, perioperative chemotherapy, and emerging therapies offer hope for improved outcomes and quality of life for PMP patients.

Ovarian Causes of Pseudomyxoma Peritonei (PMP)-A Literature Review

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare, progressive, slowly growing, inadequately understood neoplasm with a 5-year progression-free survival rate of as low as 48%. It is characterized by varying degrees of malignancy and the production of mucinous and gelatinous structures. Typically, the development of pseudomyxoma peritonei is associated with the rupture of appendiceal mucinous tumors and other gastrointestinal or ovarian mucinous tumors. The goal of our literature review was to identify various aspects that characterize the ovarian causes of pseudomyxoma peritonei.

MATERIALS AND METHODS

The authors performed an extensive literature search between 1 February 2024 and 2 March 2024 on the following databases: Pubmed, Scopus, Oxford Journals, and Reaxys, and the findings were summarized into seven main clinical and paraclinical situations.

RESULTS

According to our research, the main instances in which pseudomyxoma peritonei can be triggered by an ovarian cause are the following: (1) mucinous cystadenoma; (2) mucinous ovarian cancer; (3) colon cancer with ovarian metastasis; (4) malignant transformation of an ovarian primary mature cystic teratoma; (5) appendiceal mucocele with peritoneal dissemination mimicking an ovarian tumor with peritoneal carcinomatosis; (6) mucinous borderline tumor developing inside an ovarian teratoma; and (7) the association between a mucinous bilateral ovarian cancer and a colonic tumor.

CONCLUSIONS

In our study, we aimed to provide a comprehensive overview of the ovarian causes of pseudomyxoma peritonei, including its epidemiology, imagery characteristics, symptoms, current treatment, and promising future therapies, in the hopes of finding feasible solutions, as a lack of understanding of this mucus-secreting malignant disease increases the risk of delayed diagnosis or uncontrolled deterioration.

Mucocoele of the appendix

Introduction

Mucocoele of the appendix occurs in 0.2-0.7% of people in the world without any well-defined clinical symptoms. It occurs when there is an accumulation of mucous in the lumen of the appendix.

Case Presentation

We present three cases: a 48-year-old male admitted to the emergency room with a one-day history of right iliac fossa pain. Abdominal examination was suggestive of acute appendicitis. The initial abdominal computerised tomography scan was reported as being unremarkable. At surgery, a firm tumour of the appendix was found, and a limited right hemicolectomy was done. Histopathology confirmed a mucocoele of the appendix with borderline mucinous histology.The second case is a 63-year-old man who presented with a one-year history of abdominal distension and weight loss. Previous abdominal ultrasound was suggestive of liver cirrhosis with significant ascitic fluid. Abdominal magnetic resonance imaging found an appendix mucocoele with infiltration of the omentum and scalloping of the liver surface suggestive of pseudomyxoma peritonei. A percutaneous biopsy of the omental mass confirmed metastatic mucinous adenocarcinoma of the appendix.The third case is a 68-year-old man who, during an annual medical check-up, had an incidental finding of a cystic right iliac fossa mass on ultrasound, confirmed on abdominopelvic computerised tomography scan to be an appendix mucocele. He had laparoscopic appendicectomy. The histopathological diagnosis confirmed a mucinous cystadenoma of the appendix.

Conclusion

Preoperative diagnosis of appendiceal mucocoele is difficult and commonly discovered intraoperatively. The prognosis is good for the histologically benign type, but it is poor when malignant or peritoneal lesions are present.

Funding

None declared.

[Multi-Detector CT Findings of Typical and Atypical Appendicitis: A Pictorial Essay]

Multi-detector CT (MDCT) is a highly accurate diagnostic tool that is commonly used to evaluate appendicitis and its complications. The diagnosis of appendicitis based on MDCT findings can be difficult and challenging when the observed findings are inconsistent with the typical features. Atypical appendicitis includes a wide spectrum of features, such as variable positions of the appendix and cecum, complications, and unusual pathological findings of secondary appendicitis that mimic or induce appendicitis. Our pictorial essay describes the diverse spectrum of atypical appendicitis and appendicitis-like conditions in terms of location abnormalities, complications, and uncommon pathologies, including related tumors, reactive appendicitis, appendiceal diverticulitis, and IgG4-related disease. Through this essay, the readers can become more familiar with MDCT findings of atypical appendicitis.

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.

Mucocele of the appendix: what to expect

Mucoceles of the appendix are rare and can have quite variable imaging and clinical presentations, sometimes mimicking an adnexal mass. The underlying cause can be neoplastic or non-neoplastic. The typical imaging appearance of a mucocele of the appendix is that of a cystic structure with a tubular morphology. This structure is defined by having a blind-ending and being contiguous with the cecum. Radiologists should be familiar with key anatomical landmarks and with the various imaging features of mucoceles of the appendix, in order to provide a meaningful differential diagnosis of a lesion in the right lower abdominal quadrant. In addition, a neoplastic mucocele can rupture, resulting in pseudomyxoma peritonei, which will change the prognosis dramatically. Therefore, prompt diagnostic imaging is crucial.

Comprehensive Understanding and Evolutional Therapeutic Schemes for Pseudomyxoma Peritonei: A Literature Review

Pseudomyxoma peritonei is an infrequent solid tumor in clinical practice. The low morbidity and deficient understanding of this mucus-secreting malignant disease increase the risks of delayed identification or uncontrollable deterioration. In quite a lot cases, patients go through complete cytoreduction surgery and hyperthermic intraperitoneal chemotherapy could receive a long time survival over 5 years. But the recurrence rate is also hard to overlook. Unlike other types of cancer, the standard treatment for this considerable groups has not been confirmed yet. With the advanced medical progression, studies have been carrying out based on pathogenesis, biological characters, and mutated gene location. All but a few get statistical survival benefits, let alone the breaking progress on research or therapeutic practice in the field. We try to give a comprehensive exposition of pseudomyxoma peritonei around the epidemiology, radiologic features, clinical manifestation, present treatment and promising schemes, hoping to arise much attention and reflection on the feasible solutions, especially for the recrudescent part.

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.

Pseudomyxoma peritonei of appendiceal origin mimicking ovarian cancer - a case report with literature review

Pseudomyxoma peritonei (PMP) is a rare and uncommon condition, characterized by the presence of mucinous ascites in the abdominal cavity. The most common cause of PMP is mucinous adenocarcinoma of the appendix, followed by neoplasms of the ovary, endocervix, fallopian tube, alimentary organs, urachus, urinary bladder, lung, mucinous cyst of the spleen, and breast.

Herein, we report a case of a 64-year-old postmenopausal woman (gravida 2, para 2) who presented at the department of gynecology with a short history of nausea and abdominal distention. Abdominal and vaginal ultrasonography showed a large amount of free fluid in the pelvis with hyperechoic echogenicity and right pelvic tumor with mixed echogenicity. Computed tomography demonstrated the presence of a heterogeneous, hypodense mass, without contrast enhancement, located on the right side of the pelvis, near the right ovary. Laparotomy was performed. Revision of the abdominal cavity revealed a large amount of yellow gelatinous mucinous ascites – approximately 1.5 l. A tumor (6 x 7 cm in diameter), arising from the appendix and located in the pouch of Douglas near the right ovary, was observed. Histopathology examination revealed poorly differentiated mucinous appendiceal adenocarcinoma, comprising up to 50% signet ring cells.

Gastrointestinal tumors such as appendiceal neoplasms combined with PMP may mimic ovarian carcinomas. Computed tomography, abdominal/vaginal ultrasonography and tumor marker levels (carcino-embryonic antigen, carbohydrate antigen 19.9, carbohydrate antigen Ca-125) may establish the diagnosis.

A differential diagnosis with appendiceal tumors should be considered for patients with right pelvic masses.

Ultrasound for Preoperatively Predicting Pathology Grade, Complete Cytoreduction Possibility, and Survival Outcomes of Pseudomyxoma Peritonei

Objectives

This study aimed to investigate the value of using ultrasound (US) preoperatively for predicting pathological classification, complete cytoreduction possibility, and survival rate of patients with pseudomyxoma peritonei (PMP).

Methods

We retrospectively studied PMP patients who were scheduled for cytoreductive surgery between May 2009 and October 2019. US examination was performed before surgery. Factors related to high-grade pathology and poor completeness of cytoreduction (CC) score were identified. Associations between ultrasound characteristics and the survival status were also examined to identify independent predictive factors.

Results

PMP patients with clear ascites, abdominal lymph nodes, omental cake, abdominal mass, portal infiltration, and mesenteric involvement visible on US were considered to have high-grade pathology. Various US features were shown to be independent prognostic markers for inadequate cytoreduction in PMP patients. Portal infiltration and mesenteric involvement were significant prognostic factors for lower survival rates (hazard ratio = 3.092, 3.932, respectively). A visual nomogram including these factors was constructed to predict survival rates. The consistency index was 0.777, which reflected relatively high accuracy.

Conclusions

Preoperative US has the potential to predict pathological grade and resectability of PMP. Portal infiltration and mesenteric involvement were independent predictors of poor clinical outcomes in PMP patients. Furthermore, a simple-to-use nomogram derived from our study data may be a helpful visual tool in clinical practice to predict 1-, 2-, and 3-year survival rates for PMP patients.

Clues to the diagnosis of borderline ovarian tumours: An imaging guide

Borderline Ovarian Tumours (BOTs) are an interesting subset of epithelial neoplasms defined histologically by atypical epithelial proliferation without stromal invasion. These tumours typically affect young women in the reproductive age group and have a good prognosis. Although ultrasonography is the primary screening imaging technique in the evaluation of any suspected adnexal mass, grey-scale and colour Doppler have limited value in characterizing BOTs. Thus, a pelvic magnetic resonance imaging (MRI) is recommended for further characterization on account of its multiplanar capabilities, excellent soft-tissue contrast and high spatial resolution. BOTs histological subtypes display specific features on MRI that are useful in differential diagnosis. However, the final diagnosis and staging of BOTs require pathologic evaluation after surgical excision. Therefore, the purpose of this review is to describe, illustrate and compare the imaging characteristics of the different subtypes of BOTs - serous, mucinous and seromucinous - focusing on MRI, as well as to correlate with pathology findings considering the recent 2020 World Health Organization (WHO) classification, in order to improve the accuracy of preoperative diagnosis and facilitate optimal patient management.