Appendiceal mucinous tumors and pseudomyxoma peritonei: histologic features, diagnostic problems, and proposed classification

Connecting the dots: Low-grade appendiceal mucinous neoplasms and serrated polyps in the appendix

OBJECTIVE

This study aimed to examine the relationship between low-grade appendiceal mucinous neoplasms (LAMNs) and serrated polyps (SPs) of the appendix, both characterized by KRAS mutations and overlapping morphologic features.

METHODS

We analyzed 27 cases of LAMN and 24 cases of SP from archival records, reviewed pathology, and performed molecular analysis on select cases. Four cases initially diagnosed as LAMN were excluded for not meeting diagnostic criteria, and 1 SP case was reclassified as LAMN.

RESULTS

Microscopic evaluation revealed serrated architecture in 8 (29.6%) of 27 LAMNs: 4 hyperplastic polyp-like, 2 sessile serrated lesion-like (SSL), and 1 traditional serrated adenoma-like (TSA). One case exhibited both SSL- and TSA-like areas. Among SPs, 3 (12.5%) of 24 cases showed morphologic overlap with LAMN due to cytoplasmic mucin, flattened mucosa, and conventional adenoma-like features; all were grossly visible. KRAS was the most common mutation in LAMNs with serrated architecture (4/4, 100%), 1 classic LAMN, and 1 SP with dysplasia and associated signet-ring cell carcinoma.

CONCLUSIONS

Serrated polyps and LAMNs likely represent a biological continuum, sharing key features such as KRAS mutations and morphologic overlap. Our findings underscore the need for careful molecular and histopathologic evaluation in diagnosing these neoplasms.

Pseudomyxoma peritonei originating from small intestine: A case report and review of literature

BACKGROUND

Pseudomyxoma peritonei (PMP) is a distinct form of peritoneal malignancy characterized by diffuse intra-abdominal gelatinous ascites, with an estimated incidence of 1-3 per 1000000. PMP is predominantly secondary to appendiceal mucinous neoplasms, with rarer origins including the ovaries, colon, and urachus. However, PMP originating from small intestine is extremely rare.

CASE SUMMARY

A 60-year-old male patient presented with anorexia and abdominal distension. Computed tomography revealed the presence of abdominopelvic effusions and multiple intra-abdominal space-occupying lesions. Ultrasound-guided aspiration indicated that the aspirated tissue was mucinous. Exploratory laparoscopy and tissue biopsy identified diffuse tumor nodules in peritoneum, omentum, pelvic region, intestinal walls, and mesentery. Histopathological analysis of the resected tumors confirmed the presence of mucinous adenocarcinoma, but the primary lesion was difficult to determine. The patient was referred to our center for further treatment and underwent cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) under general anesthesia. The intraoperative peritoneal cancer index was 30. The surgery lasted 8 hours, with a blood loss of about 600 mL. A complete cytoreduction (CCR0) was achieved. No serious complications occurred after surgery, and the patient's condition was good during the telephone follow-up. Postoperative pathology confirmed the diagnosis of small intestinal mucinous adenocarcinoma at proximal jejunum, which was complicated by high-grade PMP.

CONCLUSION

PMP originating from small intestine is an exceptionally rare entity that exhibits non-specific clinical features. The preferred treatment is CRS + HIPEC.

Overview: Challenges of Treating Peritoneal Surface Malignancies

Peritoneal surface malignancies (PSM) includes an expansive disease spectrum, ranging from low-grade appendiceal mucinous neoplasm to metastatic processes from invasive adenocarcinomas of the gastrointestinal tract. Management of PSM faces numerous challenges, from diagnosis to delivery of care, both from a treatment and navigational standpoint. This article outlines the various hurdles faced at different branch points and current management recommendations.

TP53 Alterations Are an Independent Adverse Prognostic Indicator in Pseudomyxoma Peritonei of Appendiceal Origin Following Cytoreductive Surgery and Intraperitoneal Chemotherapy

Histologic grade is a key predictor for pseudomyxoma peritonei (PMP) of appendiceal origin that is used to guide clinical management. However, some tumors demonstrate disease behavior that deviates from their histologic grade. A recent study suggested that TP53, GNAS , and RAS mutation analysis could stratify tumors into distinct molecular groups with different prognosis. We investigated molecular alterations in 114 patients with PMP of appendiceal origin who were uniformly treated with cytoreductive surgery with intraperitoneal chemotherapy (CRS+IPCT). Tumors were separated into 4 groups based on their predominant genomic alteration: RAS -mut, GNAS -mut, TP53 -mut, and triple-negative ( RAS/GNAS/TP53 -wildtype). The results were correlated with World Health Organization (WHO) grade, peritoneal carcinomatosis index (PCI), completeness of cytoreduction (CC) score, and overall survival (OS) from the time of CRS+IPCT using multivariate Cox proportional hazard analysis. Fifty percent of TP53 -mut were WHO grade 3 compared with 38% triple-negative, 10% RAS -mut, and 7% GNAS -mut tumors ( P <0.001). The TP53 -mut group exhibited a significantly reduced OS compared with other groups ( P <0.001). No significant OS difference was identified between RAS -mut, GNAS -mut, and triple-negative groups ( P >0.05). In grade 3 PMP, TP53 -mut was significantly associated with reduced OS ( P =0.002). In the multivariate analysis for OS after CRS+IPCT, TP53 -mut [hazard ratio (HR) 3.23, P =0.004] and WHO grade (grade 2 HR 2.73, P =0.03 and grade 3 HR 5.67, P <0.001) were the only independent predictors of survival. Our results suggest that, in addition to tumor grade, TP53 status may help to provide a more patient-centered approach in guiding therapy in PMP.

Mucocele of the rectal stump: mucinous cystic neoplasm with low-grade dysplasia simulating low-grade appendiceal mucinous neoplasm

Mucoceles, commonly observed in the appendix, are mucin-filled, dilated structures arising from a range of etiologies. Cases associated with dysplastic or neoplastic epithelium can rupture and disseminate within the abdominopelvic cavity. Similar lesions in other parts of the colon are exceedingly rare, with only 16 colonic mucoceles having been reported. The first case of a colonic mucinous neoplasm with dysplasia resembling a low-grade appendiceal mucinous neoplasm involving rectal stump was described in 2016. Here, we present the second such case arising in the rectal stump, identified in a 44-year-old male with extensive surgical history. Microscopic examination revealed low-grade dysplastic epithelium lining the cyst and mucin dissecting into the stroma, without evidence of rupture or extramural mucin. The patient was followed for 16 months without recurrence or peritoneal disease. The exact etiology and outcome of these rare lesions remain unknown, requiring close follow-up.

Decision Regret in Patients with Appendiceal Cancer Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

BACKGROUND

Decision regret is an emerging patient reported outcome. The aim of this study was to assess the incidence of regret in patients with appendiceal cancer (AC) who underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC).

PATIENTS AND METHODS

An anonymous survey was distributed to patients through the Appendix Cancer and Pseudomyxoma Peritonei (ACPMP) Research Foundation. The Decision Regret Scale (DRS) was employed, with DRS > 25 signifying regret. Patient demographics, tumor characteristics, postoperative outcomes, symptoms (FACT-C), and PROMIS-29 quality of life (QoL) scores were compared between patients who regretted or did not regret (NO-REG) the procedure.

RESULTS

A total of 122 patients were analyzed. The vast majority had no regret about undergoing CRS-HIPEC (85.2%); 18 patients expressed regret (14.8%). Patients with higher regret had: income ≤ $74,062 (72.2% vs 44.2% NO-REG; p = 0.028), major complications within 30 days of surgery (55.6% vs 15.4% NO-REG; p < 0.001), > 30 days hospital stay (38.9% vs 4.8% NO-REG; p < 0.001), a new ostomy (27.8% vs 7.7% NO-REG; p = 0.03), >1 CRS-HIPEC procedure (56.3% vs 12.6% NO-REG; p < 0.001). Patients with worse FACT-C scores had more regret (p < 0.001). PROMIS-29 QOL scores were universally worse in patients with regret. Multivariable analysis demonstrated > 30 days in the hospital, new ostomy and worse gastrointestinal symptom scores were significantly associated with regret.

CONCLUSIONS

The majority of patients with AC undergoing CRS-HIPEC do not regret undergoing the procedure. Lower income, postoperative complications, an ostomy, undergoing > 1 procedure, and with worse long-term gastrointestinal symptoms were associated with increased regret. Targeted perioperative psychological support and symptom management may assist to ameliorate regret.

Appendiceal adenocarcinoma: Current concepts & challenges

Appendiceal adenocarcinoma (ApAC) is a rare malignancy, comprising less than 1 % of all gastrointestinal tumors. The current World Health Organization classifies ApAC as mucinous or nonmucinous. Mucinous ApAC are composed of pools of mucin lined by cells with low- and high-grade cytology and areas of infiltrative invasion. Nonmucinous ApAC histologically resemble conventional colorectal adenocarcinomas and have a worse prognosis than their mucinous counterpart. Unfortunately, the nomenclature and histologic classification of ApAC, specifically the mucinous subtype, has changed several times throughout the years, contributing to diagnostic confusion for pathologists. The treatment for mucinous ApAC differs from that of other appendiceal mucinous neoplasms, thus accurate diagnosis is key to patient management and outcome. This review discusses the current classification and staging of ApAC with a particular emphasis on the mucinous subtype and peritoneal disease, as these areas are the most challenging for practicing surgical pathologists.

Massive appendiceal mucinous neoplasm diagnosed after abdominal trauma: Pitfalls in imaging and diagnosis

Low grade appendiceal mucinous neoplasm (LAMN) is a rare tumor presenting typically with symptoms of acute appendicitis. A 33-year-old gentleman presented with abdominal fullness and discomfort secondary to abdominal trauma obtained during boxing training. Investigations with magnetic resonance imaging (MRI), ultrasound, and colonoscopy revealed a large cystic lesion in the ascending colon mesentery with unclear continuation with the appendix. There were no obvious features of malignancy. Laparoscopy revealed a large, firm mass connected to the appendix with enlarged lymph nodes, and the patient underwent radical resection with a right hemicolectomy. Histopathology revealed complete excision of LAMN with no lymphatic involvement. Post traumatic intra-abdominal cystic lesions pose a diagnostic challenge, and neoplastic lesions cannot be ruled out with imaging alone, even with benign appearances. Careful surgical excision and histopathological diagnosis is the only definitive method of ruling-out malignancy.

Mucinous neoplasm of the appendix: A case report and review of literature

BACKGROUND

Appendiceal mucinous neoplasms (AMNs), although not classified as rare, are relatively uncommon tumors most often discovered incidentally during colorectal surgery. Accurate identification of AMNs is difficult due to non-specific symptoms, overlapping tumor markers with other conditions, and the potential for misdiagnosis. This underscores the urgent need for precision in diagnosis to prevent severe complications.

CASE SUMMARY

This case report describes the unexpected discovery and treatment of a low-grade AMN (LAMN) in a 74-year-old man undergoing laparoscopic hemicolectomy for transverse colon adenocarcinoma (AC). Preoperatively, non-specific gastrointestinal symptoms and elevated tumor markers masked the presence of AMN. The tumor, presumed to be an AMN peritoneal cyst intraoperatively, was confirmed as LAMN through histopathological examination. The neoplasm exhibited mucin accumulation and a distinct immunohistochemical profile: Positive for Homeobox protein CDX-2, Cytokeratin 20, special AT-rich sequence-binding protein 2, and Mucin 2 but negative for cytokeratin 7 and Paired box gene 8. This profile aids in distinguishing appendiceal and ovarian mucinous tumors. Postoperative recovery was uncomplicated, and the patient initiated adjuvant chemotherapy for the colon AC.

CONCLUSION

This case highlights the diagnostic complexity of AMNs, emphasizing the need for vigilant identification to avert potential complications, such as pseudomyxoma peritonei.

Does a Positive Appendiceal Resection Margin in Low-Grade Appendiceal Mucinous Neoplasms, Warrant Additional Surgery? Our Institution Experience and Literature Review

BACKGROUND

Management of low-grade appendiceal mucinous neoplasm (LAMN) with positive resection margin is controversial. Some guidelines recommend surgical reexcision, whereas others recommend a conservative approach. The purpose of our study was to determine whether involvement of the resection margin by LAMN is a risk factor for local recurrence requiring additional surgery.

DESIGN

This is a retrospective study (January 2000-December 2020) of uncomplicated LAMNs with neoplastic epithelium or dissecting mucin at the resection margin. For cases treated with additional surgery, the presence of residual tumor was evaluated. Clinical follow-up was attained in all cases. We also conducted a literature review.

RESULTS

The study investigated 98 patients. Eight with median age of 67 (range: 45-91) years had a LAMN involving the resection margin (8.2%). Five of eight LAMNs (62.5%) with neoplastic epithelium at the margin underwent surgery, and no residual neoplasm was identified. The other three cases were followed conservatively, and no patient developed recurrence (follow-up: 18-69 months with a mean of 45 months). In a review of the literature, we identified 52 LAMNs with positive margin. Although three cases had acellular mucin and one residual LAMN in the reexcision specimen (7.7%), neither of these four cases or any of the other 46 followed conservatively had recurrence of disease.

CONCLUSIONS

These data suggest that for patients with uncomplicated LAMN confined to the appendix, the involvement of the appendiceal margin does not necessary lead to recurrence of LAMN, and a conservative management is a reasonable alternative.

Incidence and outcomes of delayed presentation and surgery in peritoneal surface malignancies

Background

Peritoneal surface malignancies (PSM) present insidiously and often pose diagnostic challenges. There is a paucity of literature quantifying the frequency and extent of therapeutic delays in PSM and its impact on oncological outcomes.

Methods

A review of a prospectively maintained registry of PSM patients undergoing Cytoreductive Surgery and Hyperthermic Intra-peritoneal Chemotherapy (CRS-HIPEC) was conducted. Causes for treatment delays were identified. We evaluate the impact of delayed presentation and treatment delays on oncological outcomes using Cox proportional hazards models.

Results

319 patients underwent CRS-HIPEC over a 6-years duration. 58 patients were eventually included in this study. Mean duration between symptom onset and CRS-HIPEC was 186.0 ± 37.1 days (range 18-1494 days) and mean duration of between patient-reported symptom onset and initial presentation was 56.7 ± 16.8 days. Delayed presentation (> 60 days between symptom onset and presentation) was seen in 20.7% (n=12) of patients and 50.0% (n=29) experienced a significant treatment delay of > 90 days between 1^st presentation and CRS-HIPEC. Common causes for treatment delays were healthcare provider-related i.e. delayed or inappropriate referrals (43.1%) and delayed presentation to care (31.0%). Delayed presentation was a significantly associated with poorer disease free survival (DFS) (HR 4.67, 95% CI 1.11-19.69, p=0.036).

Conclusion

Delayed presentation and treatment delays are common and may have an impact on oncological outcomes. There is an urgent need to improve patient education and streamline healthcare delivery processes in the management of PSM.

Rare presentation of low-grade appendiceal mucinous neoplasms (LAMN) as an appendicular lump: A case report

Introduction

The prevalence of appendiceal mucinous neoplasms (AMN) is about 0.2%-0.3% in the specimens of the appendix. The LAMN may appear unremarkable or can present as mucin-filled, crystally dilated tissues. The diagnosis of early-stage AMN is mostly incidental. It is of vital importance to know the features of LAMN for a timely diagnosis.

Case presentation

A 46-year-old male came with the complaint of right iliac fossa swelling along with severe intensity pain and a single episode of vomiting. A 4 × 4cm tender, soft, cystic, mobile swelling was found upon the examination. Contrast-enhanced Computerized tomography (CT) scan of the abdomen revealed the appendix diameter of 10mm well-circumscribed cystic measuring 2.1 × 2 cm. Therefore, an open resection surgery was performed. The histopathological report revealed an intraepithelial lesion composed of flat mucinous epithelial cells having eosinophilic cytoplasm and low-grade nuclear atypia.

Case discussion

The AMNs are very rare neoplasms. The imaging modalities that can be diagnostic methods are abdominal and transvaginal ultrasonography (US), and abdominal computed tomography (CT). The low-grade features of the appendiceal mucinous neoplasms have the possibility of recurrence. The CT-scan findings of appendiceal lump>1.3cm along with cystic dilation and the calcification of the wall are the suggestive features of AMN. There is a high chance of dissemination and port site seeding in case of pneumoperitoneum.

Conclusion

This rare case suggests the significance of adding AMNs as a differential diagnosis in patients with abdominal pain and choosing the right approach to treat such patients to avoid complications.

Appendiceal mucocele with pseudomyxoma peritonei mimicking ovarian tumor with peritoneal carcinomatosis

Appendiceal mucocele with unprompted pseudomyxoma peritonei is a rare malignant tumor, which is difficult to diagnose before surgery. We present a case of a 62-year-old woman, and subsequently discuss the clinical and imaging presentation of mucoceles. Findings on CT scan suggested 2 diagnoses: appendiceal mucocele with pseudomyxoma peritonei and malignant ovarian tumor with peritoneal carcinosis. MRI suggested the former diagnosis, showing a large tubular mass at the base of appendix with discontinuous wall, and no ovarian abnormality, which was confirmed by mini laparotomy and histological study of peritoneal thickened tissue. Treatment consisted of neoadjuvant chemotherapy, with a good response. This case shows the role of imaging in the preoperative diagnosis of appendicular mucoceles; CT scan and MRI, which are useful tools in identifying undetermined lesions of the appendix.

The Role of Adjuvant Chemotherapy Following Right Hemicolectomy for Non-metastatic Mucinous and Nonmucinous Appendiceal Adenocarcinoma

BACKGROUND

Appendiceal adenocarcinoma (AA) represents a heterogenous group of neoplasms with distinct histologic features. The role and efficacy of adjuvant chemotherapy (AC) in non-metastatic disease remain controversial. The aim of this study was to ascertain the role of AC in non-metastatic AA in a national cohort of patients.

METHODS

The National Cancer Database (NCDB) was queried to identify patients diagnosed with stage I-III mucinous and nonmucinous AA who underwent right hemicolectomy between 2006 and 2016. Kaplan-Meier and Cox regression analyses were used to evaluate the impact of AC on overall survival (OS) stratified by each pathologic stage.

RESULTS

A total of 1433 mucinous and 1954 nonmucinous AA were identified; 578 (40%) and 722 (40%) received AC respectively. In both AC groups, there was a higher proportion of T4 disease, lymph node metastasis, pathologic stage III, and poorly/undifferentiated grade (all P<0.05). On unadjusted analysis, there was no significant association between AC and OS for stage I-III mucinous AA. For nonmucinous AA, AC significantly improved OS only for stage II and III disease. On adjusted analysis, AC was independently associated with an improved OS for stage III nonmucinous AA (HR: 0.61, 95%CI 0.45-0.84, P=0.002), while for mucinous AA, AC was associated with worse outcomes for stage I/II disease (HR: 1.4, 95%CI 1.02-1.91, P=0.038) and had no significant association with OS for stage III disease.

CONCLUSION

This current analysis of a national cohort of patients suggests a beneficial role for AC in stage III nonmucinous AA and demonstrates no identifiable benefit for stage I-III mucinous AA.

Treatment of a giant low-grade appendiceal mucinous neoplasm: A case report

BACKGROUND

Low-grade appendiceal mucinous neoplasm (LAMN) is extremely rare and easily misdiagnosed before surgery.

CASE SUMMARY

We report the treatment of an asymptomatic case of LAMN diagnosed by magnetic resonance imaging (MRI) and surgical findings. A 70-year-old woman presented with an adnexal mass found by physical examination in July 2020. Gynecologic ultrasonography revealed a cystic mass in the right adnexa, and computed tomography showed a cystic mass in the pelvic cavity. All tumor markers were normal. A further MRI examination suggested mucinous neoplasm in the right pelvic cavity, excluding the possibility of adnexal cyst. Laparoscopic exploration found a huge cystic mass of about 10 cm × 7 cm that originated from the apex of the appendix, with spontaneous rupture. LAMN was confirmed by pathological examination. As of May 2021, no disease recurrence occurred after an open appendectomy.

CONCLUSION

This case indicates that we should pay more attention to female patients who are clinically diagnosed with an adnexal mass at admission,. The physical examination should be done carefully, and the laboratory and imaging examination results should be comprehensively analyzed to avoid misdiagnosis and to ensure prompt diagnosis and treatment, and to improve prognosis. MRI may be a better option for the diagnosis of appendiceal mucinous neoplasm.

Hyperthermic Intraperitoneal Chemotherapy: A Critical Review

Simple Summary

Patients with cancer of the digestive system or ovarian cancer are at risk of developing peritoneal metastases (PM). In some patients with PM, surgery followed by intraperitoneal (IP) chemotherapy has emerged as a valid treatment option. The addition of hyperthermia is thought to further enhance the efficacy of IP chemotherapy. However, the results of recent clinical trials in large bowel cancer have put into question the use of hyperthermic intraperitoneal chemotherapy (HIPEC). Here, we review the rationale and current results of HIPEC for PM and propose a roadmap to further progress.

Abstract

With increasing awareness amongst physicians and improved radiological imaging techniques, the peritoneal cavity is increasingly recognized as an important metastatic site in various malignancies. Prognosis of these patients is usually poor as traditional treatment including surgical resection or systemic treatment is relatively ineffective. Intraperitoneal delivery of chemotherapeutic agents is thought to be an attractive alternative as this results in high tumor tissue concentrations with limited systemic exposure. The addition of hyperthermia aims to potentiate the anti-tumor effects of chemotherapy, resulting in the concept of heated intraperitoneal chemotherapy (HIPEC) for the treatment of peritoneal metastases as it was developed about 3 decades ago. With increasing experience, HIPEC has become a safe and accepted treatment offered in many centers around the world. However, standardization of the technique has been poor and results from clinical trials have been equivocal. As a result, the true value of HIPEC in the treatment of peritoneal metastases remains a matter of debate. The current review aims to provide a critical overview of the theoretical concept and preclinical and clinical study results, to outline areas of persisting uncertainty, and to propose a framework to better define the role of HIPEC in the treatment of peritoneal malignancies.

Clinicopathological Features of Low-Grade Appendiceal Mucinous Neoplasms Confined to the Appendix

OBJECTIVE

To investigate the clinicopathological features and follow-up of low-grade appendiceal mucinous neoplasms (LAMNs) confined to the appendix.

METHODS

The clinicopathological features, pathological primary tumor (pT) staging and follow-up of 22 patients with LAMNs confined to the appendix were analyzed retrospectively.

RESULTS

Of 22 patients with LAMNs, 14 were pTis (eight pTis^m and six pTis^f), six were pT3, and two were pT4a. The appendiceal diameter was significantly larger for pTis^f than for pTis^m. The interval between first symptoms and surgery was longer for pTis^f than for pTis^m, but not significantly different. No significant differences were found between the pT stages and appendiceal diameter or in the interval between the first symptoms and surgery. Pathomorphologically, the epithelial structures were mainly flat (100%), undulating or scalloped (82%); a few showed filiform villous hyperplasia (46%), and seven (32%) had serrated lesions in the background. Diverticula may be associated with LAMNs, and the location of acellular mucin caused by diverticula affected the pT stage of the LAMNs. The immunohistochemistry information showed the same pattern with cytokeratin 7 (CK7) negative, cytokeratin 20 (CK20) positive and caudal type homeobox 2 (CDX-2) positive. No lymph node metastasis was found. The lack of treatment guidelines for LAMNs confined to the appendix and different acceptances of patients of preventive intervention led to varied clinical treatments. However, we found no short-term benefits of prophylactic extended resection or hyperthermic intraperitoneal chemotherapy.

CONCLUSION

LAMNs confined to the appendix are rare and must be differentiated from serrated lesions and diverticula. LAMNs with different pT stages have inert biological behavior. Determining the long-term effects of preventive treatment on survival and recurrence requires more data and a longer follow-up.

Germline and somatic genetic alterations in two first-degree relatives with appendiceal low-grade mucinous carcinoma peritonei

Comparing genetic mutations of first-degree relatives with appendiceal pseudomyxoma peritonei may explain clinical outcomes and disease pathogenesis. Molecular profiling of mucinous tumors may identify improved treatments to traditional chemotherapy.

First Report of a Low-Grade Pseudomyxoma peritonei Originating from Gall Bladder

Pseudomyxoma peritonei (PMP) refers to accumulation of mucinous ascites with or without neoplastic cells in the peritoneal cavity. It most commonly originates from a low or a high grade primary appendiceal mucinous neoplasm. Though adenocarcinoma of gall bladder has been reported to give rise to PMP, to the best of our knowledge, this is the first report of a PMP arising from a low grade mucinous tumour of the gall bladder. A 72-year-old patient was diagnosed with PMP 1.5 years after a cholecystectomy. After initial oral TS1 (combination of tegafur, gimeracil and oteracil) and later intraperitoneal (IP) chemotherapy with docetaxel and cisplatin, the patient was operated with the goal of tumour debulking, including removal of 5.5 L of mucinous ascites, an appendectomy, and ovariectomy. The histopathologic report showed a normal appendix and metastasis of PMP to the right ovary. After the exclusion of the 2 most common sites of origin (appendix and ovary), the specimen of the cholecystectomy was reviewed. It showed low grade mucinous tumour in the gall bladder, with immuno-histochemical markers (IHCs) suggestive of CK7, CDX2, MUC 2 positive and CK20, MUC5AC negative. MIB-1 index was 12%. The pathologic report of cytoreductive surgery performed after 7 cycles of IP chemotherapy confirmed the diagnosis of PMP originating from low grade mucinous tumour of the gall bladder. Our case report illustrates a rare disease and highlights that, though peritoneal metastasis from gall bladder cancers are known to have a poor prognosis, the peritoneal dissemination from a low grade mucinous neoplasm of gall bladder (PMP) has a significantly better prognosis due to a better disease biology and improved treatment options currently available for the treatment of PMP.

Macroscopic and microscopic characteristics of low grade appendiceal mucinous neoplasms (LAMN) on appendectomy specimens and correlations with pseudomyxoma peritonei development risk

Low grade appendiceal mucinous neoplasm (LAMN) is the primary source of pseudomyxoma peritonei (PMP). PMP may develop after seemingly complete resection of primary tumor by appendectomy, which is unpredictable due to lack of reliable prognostic indicators. We retrospectively reviewed 154 surgically resected LAMNs to explore if any of the macroscopic and microscopic characteristics may be associated with increasing risk of PMP development. Our major findings include: (1) As compared to those without PMP, the cases that developed PMP were more frequent to have (a) smaller luminal diameter (<1 cm) and thicker wall, separate mucin aggregations, and microscopic perforation/rupture, all suggestive of luminal mucin leakage; (b) microscopic acellular mucin presenting on serosal surface and not being confined to mucosa; and (c) neoplastic epithelium dissecting outward beyond mucosa, however, with similar frequency of neoplastic cells being present in muscularis propria. (2) Involvement of neoplastic cells or/and acellular mucin at surgical margin did not necessarily lead to tumor recurrence or subsequent PMP, and clear margin did not absolutely prevent PMP development. (3) Coexisting diverticulum, resulted from neoplastic or non-neoplastic mucosa being herniated through muscle-lacking vascular hiatus of appendiceal wall, was seen in a quarter of LAMN cases, regardless of PMP. The diverticular portion of tumor involvement was often the weakest point where rupture occurred. In conclusion, proper evaluation of surgical specimens with search for mucin and neoplastic cells on serosa and for microscopic perforation, which are of prognostic significance, should be emphasized.

Neoadjuvant Intraperitoneal Chemotherapy in Patients with Pseudomyxoma Peritonei-A Novel Treatment Approach

Neoadjuvant intravenous chemotherapy in patients with pseudomyxoma peritonei (PMP) has not shown convincing results. The effectiveness of neoadjuvant intraperitoneal (IP) chemotherapy has never been reported. This prospective, non-randomized phase II study included patients with PMP treated between May 2017 and December 2018, who were not considered suitable for primary cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). The majority of patients were treated with laparoscopic HIPEC (oxaliplatin 200 mg/m², 60 min, 43 °C). IP chemotherapy was started 2 weeks after docetaxel 40 mg/m² + cisplatin 40 mg/m², accompanied by oral S1 (tegafur, gimeracil, and oteracil) (50 mg/m²) for 14 days, followed by one week rest. Clinical parameters and complications were recorded. In total, 22/27 patients qualified for CRS and HIPEC after neoadjuvant treatment. A complete cytoreduction (Completeness of cytoreduction Score 0/1) could be achieved in 54.5%. The postoperative morbidity rate was 13.6% and mortality was rate 4.5%. In total, 20/22 patients had major pathological tumor responses. The mean drop in CEA was 28.2% and in the peritoneal carcinomatosis index (PCI) was 2.6. Positive or suspicious cytology turned negative in 69.2% of patients. Thus, for PMP patients who were not amenable for primary surgery, the majority received complete cytoreduction after treatment with neoadjuvant IP chemotherapy, with satisfying tumor regression and with low complication rates. The oncological benefit in terms of survival with this new treatment regimen needs to be proven.

Pseudomyxoma Peritonei Originating from Transverse Colon Mucinous Adenocarcinoma: A Case Report and Literature Review

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare neoplasm involving the peritoneum. Most PMPs are low-grade appendicular mucinous neoplasms (LAMNs). There have been no reports of PMP originating from a transverse colonic mucinous adenocarcinoma and causing metastatic mucinous adenocarcinoma. Case Presentation. We report a 46-year-old woman who presented with a right abdominal mass of more than 4-month duration. Transverse colonic mucinous adenocarcinoma, PMP, and ovarian metastatic mucinous adenocarcinoma were diagnosed. The patient's diet was normal, and she had no abdominal pain or bloating. The abdomen mass increased in the month before treatment. After chemotherapy, the transverse colon mass and ovarian giant cyst were resected and about 2000 mL of gelatinous tumor tissue was removed. Postoperative histology confirmed PMP from the transverse colonic mucinous adenocarcinoma, ovarian metastatic mucinous adenocarcinoma, and mesocolon metastatic cancer. Multiple lung metastases appeared 8 months after surgery. The patient died 29 months after surgery because of an inability to eat and poor nutrition. A systematic literature review of the management and outcome of all known similar cases is also presented.

CONCLUSIONS

This is the first report of PMP originating from a transverse colonic mucinous adenocarcinoma. It was diagnosed during resective surgery, involved ovarian metastasis, and survival was short. We did an extensive literature review in order to describe the clinical characteristics, histopathological findings, genetic profile, and potential treatments of PMP caused by nonappendiceal mucinous adenocarcinoma.

Clinicopathologic and prognostic features in appendiceal malignancies: does tumor invasiveness matter?

Objectives

To evaluate the survival rates of appendiceal tumors and prognostic factors affecting survival.

Material and Methods

Demographic features, tumor characteristics and pre- and post-operative outcomes of the patients were analyzed retrospectively. The study was performed according to the Helsinki declaration.

Results

Twenty-three of the 2840 specimens were investigated prospectively. Median age of the patients was 28 (range: 1-89) years, with a male (n= 1730, 60.9%) to female (n= 1110, 39.1%) ratio of 1.55. Pediatric group did not present appendiceal malignancy. Carcinoid tumors were reported in 17 (0.59%) and adenocarcinoma was reported in 6 (0.20%) patients. Multivariate analyses of the subtypes showed serosal invasion as an independent risk factor for mucinous and non-mucinous adenocarcinoma (HR: -2.70, 95% CI: 0.006-0.755, p= 0.029). Median follow-up time was 48 months (range: 28-61 months) and disease specific survival rates of carcinoid tumors, mucinous- and non-mucinous adenocarcinomas were 36(95% CI 32-40), 30 (95% CI 13-46), 43 (95% CI 30-55) months, respectively (p= 0.749). Factors affecting survival in the univariate analyses were advanced tumor stage, serosal invasion and tumor invasion depth. In multivariate analyses, tumor invasion depth was the only independent prognostic factor with poor survival rates in all subtypes of appendiceal malignancies (HR= 1.31 (95% CI: 1.01-13.5), p= 0.047).

Conclusion

Tumor subtype and tumor invasiveness are important risk factors for survival. Besides other treatment modalities, appendectomy still remains the survival benefit with better clinical outcomes.

Post-inflammatory mucosal hyperplasia and appendiceal diverticula simulate features of low-grade appendiceal mucinous neoplasms

Post-inflammatory mucosal hyperplasia and appendiceal diverticulosis simulate mucinous neoplasms, causing diagnostic confusion. Distinction between neoplasia and its mimics is particularly important since many authorities now consider all appendiceal mucinous neoplasms to be potentially malignant. The purpose of this study was to identify clinicopathologic and molecular features that may distinguish appendiceal mucinous neoplasms from non-neoplastic mimics. We retrospectively identified 92 mucinous lesions confined to the right lower quadrant, including 55 non-neoplastic examples of mucosal hyperplasia and/or diverticulosis and 37 low-grade neoplasms. Presenting symptoms, radiographic findings, appendiceal diameter, appearances of the lamina propria, non-neoplastic crypts, and epithelium, as well as mural changes were recorded. Twenty non-neoplastic lesions were subjected to KRAS mutational testing. Non-neoplastic appendices were smaller (p < 0.05) and more likely to present with symptoms of appendicitis (p < 0.05) than neoplasms. While post-inflammatory mucosal hyperplasia and diverticula often showed goblet cell-rich epithelium, extruded mucin pools, and patchy mural alterations with fibrosis, they always contained non-neoplastic crypts lined by mixed epithelial cell types and separated by lamina propria with predominantly preserved wall architecture. On the other hand, mucinous neoplasms lacked normal crypts (p < 0.05) and showed decreased lamina propria (p < 0.05) with diffusely thickened muscularis mucosae and lymphoid atrophy. Six (30%) non-neoplastic lesions contained KRAS mutations, particularly those containing goblet cell-rich hyperplastic epithelium. We conclude that distinction between neoplastic and non-neoplastic mucinous appendiceal lesions requires recognition of key morphologic features; KRAS mutational testing is an unreliable biomarker that cannot be used to assess biologic risk or confirm a diagnosis of neoplasia.

Intraperitoneal chemotherapy for peritoneal metastases: an expert opinion

Introduction: The rationale for intraperitoneal (IP) drug delivery for patients with peritoneal metastases (PM) is based on the pharmacokinetic advantage resulting from the peritoneal-plasma barrier, and on the potential to adequately treat small, poorly vascularized PM. Despite a history of more than three decades, many aspects of IP drug delivery remain poorly studied.Areas covered: We outline the anatomy and physiology of the peritoneal cavity, including the pharmacokinetics of IP drug delivery. We discuss transport mechanisms governing tissue penetration of IP chemotherapy, and how these are affected by the biomechanical properties of the tumor stroma. We provide an overview of the current clinical evidence on IP chemotherapy in ovarian, colorectal, and gastric cancer. We discuss the current limitations of IP drug delivery and propose several potential areas of progress.Expert opinion: The potential of IP drug delivery is hampered by off-label use of drugs developed for systemic therapy. The efficacy of IP chemotherapy for PM depends on cancer type, disease extent, and mode of drug delivery. Results from ongoing randomized trials will allow to better delineate the potential of IP chemotherapy. Promising approaches include IP aerosol therapy, prolonged delivery platforms such as gels or biomaterials, and the use of nanomedicine.

Outcomes Following Cytoreduction and HIPEC for Pseudomyxoma Peritonei: 10-Year Experience

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare clinical presentation, with considerable morbidity and mortality if left untreated. In recent decades, there is growing acceptance for the use of cytoreductive surgery (CRS) with heated intraperitoneal chemotherapy (HIPEC). The aim of this study was to report on our 10-year single-center experience on outcomes following CRS and HIPEC for PMP of appendiceal origin.

METHODS

A retrospective analysis of a prospectively maintained database of all patients undergoing CRS and HIPEC for PMP of appendiceal origin over a 10-year period at a statewide referral center was conducted.

RESULTS

One hundred and seventy-five cytoreductive procedures were undertaken in 140 patients. The mean patient age was 57.4 years, with a female preponderance (56%). The median PCI was 16, with 73.1% of cases having a complete cytoreduction. Grade III/IV complications occurred in 36 (20.6%) cases, with no mortalities. The median overall and disease-free survival was 100 months and 40 months, respectively, with a 71% 5-year survival. High-grade histology was the main factor identified as an independent predictor of worse overall survival.

CONCLUSION

CRS and HIPEC are safe with acceptable rates of morbidity. It can provide very favorable survival in patients with PMP. High-grade histology is a key prognostic factor associated with a worse overall survival.

A Case of Strangulation Ileus Due to a Low-Grade Appendiceal Mucinous Neoplasm

BACKGROUND Strangulation ileus is caused by external obstruction to the small bowel, which results in ischemia and loss of bowel peristalsis. Low-grade appendiceal mucinous neoplasm (LAMN) is a low-grade adenocarcinoma that arises in the appendix. LAMN is usually asymptomatic but can present with appendiceal rupture and pseudomyxoma peritonei (PMP). This report is of a rare presentation of LAMN with strangulation ileus in a 92-year-old man. CASE REPORT A 92-year-old man was admitted to the emergency room with sudden onset of lower abdominal pain and abdominal distension. Laboratory investigations showed a leukocytosis with a white blood cell (WBC) count of 14.6×10³/μL with 85.5% neutrophils, blood urea nitrogen (BUN) of 26.6 mg/dL, and serum creatinine of 2.6 mg/dL, consistent with acute renal failure. Arterial blood gas analysis showed lactic acidosis (pH of 7.11) with a base excess of -20.8 mmol/L and lactate of 13.7 mmol/L. Abdominal computed tomography (CT) showed ascites and a dilated obstructed closed loop of the distal ileum associated with an external mass (3.9×2.8 cm). An initial diagnosis was of strangulation ileus due to Meckel's diverticulum. Emergency ileocecal resection was performed. Histopathology showed a low-grade mucinous tumor arising from the mucosa of the appendix, consistent with LAMN. At a 13-month follow-up, the patient was well with no tumor recurrence. CONCLUSIONS This report is of a rare case of LAMN that presented as a surgical emergency with strangulation ileus.

Incidentally Discovered Appendiceal Mucinous Neoplasm in a 5-month-old Patient: A Case Report and Review of Literature

Mucocele of the appendix is a rare entity in pediatrics, and few case reports have been reported in the literature. We present the case of a 5-month-old male with abdominal distension, constipation, and vomiting who was found to have an appendiceal mucocele while being evaluated for total colonic aganglionosis. Laparoscopic-assisted resection was performed, with pathology confirming a low-grade mucinous neoplasm of the appendix. He underwent complete resection, rendering him cured without the need for any further resection or treatment.

Low-Grade Appendiceal Mucinous Neoplasms: A Single Institution Experience of 64 Cases With Clinical Follow-up and Correlation With the Current (Eighth Edition) AJCC Staging

Background. In this single-institution study, we applied the current (eighth edition) American Joint Committee on Cancer pathologic staging criteria to 64 low-grade mucinous neoplasms of the appendix (LAMNs), examined their histopathologic features, and studied the patients' clinical outcomes. Design. Sixty-four LAMNs, with a median follow-up of 52 months, were reviewed. Results. The distribution of pathologic stages was pTis (n = 39), pT3 (n = 1), pT4a (n = 5), pT4aM1a (n = 8), and pT4aM1b (n = 11). Recurrence was observed in only 2 patients (both with pT4aM1b disease), one of whom died of disease. All remaining patients were disease-free after a median clinical follow-up of 60 months. Conclusions. Our study confirms that pTis LAMNs have an excellent prognosis and suggests that pT4a and pT4aM1a LAMNs may also have a low risk of developing progressive disease.

The prognostic relevance of histologic subtype in appendiceal adenocarcinoma

BACKGROUND

The aim of this population-based study was to determine the prognostic value of the histologic subtypes mucinous (MAC), non-mucinous (AC) and signet ring cell (SRCC) adenocarcinoma among patients with appendiceal cancer.

METHODS AND MATERIALS

Data from the Netherlands Cancer Registry (NCR) of patients with primary appendiceal adenocarcinomas with MAC, AC and SRCC histologic subtype, diagnosed between 2001 and 2015 were used (n = 675). To categorize patients according to the recent histopathological classification, the NCR was linked with the Dutch Pathology Registry (PALGA). Log-rank tests and Kaplan-Meier analyses were performed to estimate overall survival (OS), and the cox proportional hazards model was run to identify prognostic factors.

RESULTS

AC was the most frequently encountered histologic subtype (50.9%), followed by MAC (35.8%) and SRCC (13.3%). In locoregional disease, histologic subtype was not a prognostic factor for OS with 5-year survival rates for patients with AC, MAC and SRCC of 60.0%, 60.5% and 69.6% respectively (p = 0.68). Metastatic disease was more common in SRCC (53.8%) than in MAC (38.8%) and AC (23.4%) (p < 0.0001). Median OS for patients with metastatic disease was 12.6, 27.7 and 18.2 months in AC, MAC and SRCC respectively (p < 0.005). MAC was associated with higher survival compared to AC (HR 0.48, 95%CI 0.34-0.69). In subanalyses, MAC was only a positive prognostic factor compared to AC in patients with peritoneal metastases (HR 0.42, 95%CI 0.28-0.62).

CONCLUSION

Histologic subtype had no prognostic relevance in locoregional or systemic metastatic disease in appendiceal adenocarcinoma. In peritoneal metastases, mucinous histologic subtype was a favorable prognostic factor, compared to non-mucinous and signet ring cell subtype.

Mucocele of the appendix presenting as an exacerbated chronic tubo-ovarian abscess: A case report and comprehensive review of the literature

RATIONALE

Appendiceal mucocele is a rare entity of mucinous cystic dilatation of the appendix. It has no typical clinical presentation and is considered a potentially premalignant condition.

PATIENT CONCERNS

We present a case of accidental intraoperative finding of an appendiceal mucocele in a 54-year old woman that clinically presented with an exacerbated chronic tubo-ovarian abscess.

DIAGNOSES

Trans-vaginal ultrasonography showed an encapsulated, oval, unilocular mass above the uterus with a heteroechogenic structure, homogeneous fluid content, and smooth regular walls without inner proliferation. The histopathologic diagnosis was consistent with an appendiceal cystadenoma.

INTERVENTIONS

The patient underwent a simple appendectomy.

OUTCOMES

There were no clinical, biochemical or imaging signs of the disease recurrence at 6 months follow up.

LESSONS

To our knowledge, this is the only well-documented case of appendiceal mucocele mimicking exacerbated chronic tubo-ovarian abscess reported in the literature. Awareness of a rare entity such as an appendiceal mucocele, which is frequently misdiagnosed as a potential cause of acute abdomen, is necessary for the appropriate management strategy in order to prevent complications.

Discrimination of low- and high-grade appendiceal mucinous neoplasms by targeted sequencing of cancer-related variants

DNA was obtained from matching micro-dissected, primary tumor cells, paired metastases, and peripheral blood mononuclear cells (germline) from patients with appendiceal mucinous neoplasms. We compared specimens from patient cohorts comprising low-grade adenomucinous neoplasm versus high-grade mucinous adenocarcinoma using a targeted, amplicon sequencing panel of 409 cancer related genes (Ion Torrent Comprehensive Cancer Panel, Thermo-Fisher, Waltham, MA). Copy number variants, single nucleotide variants and small insertions/deletions were identified using a multiplex algorithm pipeline (GATK, VarScan2, MuTect2, SIFT, SIFT-INDEL, PolyPhen-2, Provean). There were significantly more damaging variants in high-grade versus low-grade tumor cohorts. Both cohorts contained damaging, heterozygous germline variants (catenin β1; notch receptor 1 and 4) in pathways associated with cell-lineage specification (WNT, NOTCH). Damaging, somatic KRAS proto-oncogene, GTPase mutations were present in both cohorts, while somatic GNAS complex locus mutations were confined to low-grade neoplasms. Variants predominantly affected transcription factors, kinases, and stem cell signaling molecules in canonical pathways including epithelial to mesenchymal transition, stem cell pluripotency, p53, PTEN, and NF-қB signaling pathways. High-grade tumors demonstrated MYC proto-oncogene, bHLH transcription factor (MYC) and death domain associated protein (DAXX) amplification and damaging somatic variants in tumor protein p53 (TP53), likely to amplify an aggressive phenotype. Damaging APC, WNT signaling pathway regulator (APC) deletions were identified in metastatic tissue of both cohorts suggesting a role in invasive disease. Our data suggest that germline dysregulation of WNT and/or NOTCH pathways predisposes patients toward a secretory cell phenotype (i.e., goblet-like cells) upon acquisition of somatic KRAS mutations. Additional somatically acquired variants activating oncogenes MYC and DAXX and inhibiting the critical tumor suppressor, tumor protein TP53, were consistent with manifestation of a high-grade phenotype. These additional changes within the epithelial to mesenchymal transition signaling network (WNT, NOTCH, RAS/ERK/PI3K, PTEN, NF-қB), produce aggressive high-grade tumor characteristics by actively driving cells towards dedifferentiation, proliferation, and migration.

Survival outcomes of appendiceal mucinous neoplasms by histological type and stage: Analysis of 266 cases in a multicenter collaborative retrospective clinical study

AIM

Appendiceal mucinous neoplasms are rare, and thus the literature is sparse with regard to histological types, staging, and prognosis. In particular, it is unclear how long-term outcome may differ between mucinous adenocarcinomas and other adenocarcinomas. In the present study, we aimed to investigate the histological types and stages of appendiceal neoplasms, and to evaluate the prognostic impacts of these factors in patients with mucinous adenocarcinomas and non-mucinous adenocarcinomas.

METHODS

Patients with appendiceal tumors diagnosed between 2007 and 2016 were retrospectively identified from the databases of 19 institutions in the Clinical Study Group of Osaka University, Colorectal Group.

RESULTS

A total of 266 patients with appendiceal tumors were identified, of whom 130 had pathologically diagnosed adenocarcinomas, including 57 with mucinous adenocarcinomas and 73 with non-mucinous adenocarcinomas. Five-year overall survival (OS) rates were 64.5% for mucinous adenocarcinomas, and 49.0% for non-mucinous adenocarcinomas. OS was significantly shorter among patients with non-mucinous adenocarcinomas compared to mucinous adenocarcinomas. Among patients with mucinous adenocarcinomas, 5-year OS rates were 53.6% for stage 0/I, 82.6% for II/III, and 48.4% for IV. Among patients with non-mucinous adenocarcinomas, 5-year OS rates were 90.9% for stage 0/I, 68.8% for II/III, and 7.1% for IV. Analysis of patients with stage IV disease revealed significantly shorter OS among patients with non-mucinous adenocarcinomas compared to mucinous adenocarcinomas.

CONCLUSION

Our present findings showed a better prognosis in patients with mucinous adenocarcinomas compared to non-mucinous adenocarcinomas. In this setting, Union for International Cancer Control staging was associated with prognosis for non-mucinous adenocarcinomas, but not for mucinous adenocarcinomas.

Pseudomyxoma peritonei induced by low-grade appendiceal mucinous neoplasm accompanied by rectal cancer: a case report and literature review

Background

Pseudomyxoma peritonei (PMP) is a disease involving the peritoneum characterized by the production of large quantities of mucinous ascites. PMP has a low incidence, is difficult to diagnose, and has a guarded prognosis. PMP induced by low-grade appendiceal mucinous neoplasm is extremely rare, and PMP accompanied by rectal cancer is even rarer.

Case presentation

We present a unique case of a 70-year-old male with PMP induced by low-grade appendiceal mucinous neoplasm accompanied by rectal cancer. The patient’s clinical, surgical, and histologic data were reviewed. The patient had persistent distended abdominal pain without radiating lower back pain, abdominal distension for 1 month, and no exhaustion or defecation for 4 days. A transabdominal ultrasound-guided biopsy was performed on the first day. The patient received an emergency exploratory laparotomy because of increased abdominal pressure. We performed cytoreductive surgery, enterolysis, intestinal decompression, special tumour treatment and radical resection of rectal carcinoma. The postoperative course was uneventful. The postoperative histological diagnoses were PMP, low-grade appendiceal mucinous neoplasm and rectal medium differentiated adenocarcinoma. At the 1-year follow-up visit, no tumour recurrence was observed by computed tomography (CT). We also performed a literature review.

Conclusions

We should be aware that PMP can rarely be accompanied by rectal cancer, which represents an easily missed diagnosis and increases the difficulty of diagnosis and treatment. Additionally, there are some typical characteristics of PMP with respect to diagnosis and treatment.

Predicting Underlying Neoplasms in Appendiceal Mucoceles at CT: Focal Versus Diffuse Luminal Dilatation

OBJECTIVE. The purpose of this study was to determine whether a novel morphologic characteristic of appendiceal mucoceles at CT-focal distal appendiceal dilatation with a segment of morphologically normal appendix proximally-could predict an underlying neoplastic pathologic abnormality before surgery and histopathologic assessment. MATERIALS AND METHODS. A retrospective study was performed that assessed CT cases from 2012 through 2014. Cases showing morphologic features of a mucocele were identified and categorized into two subgroups: focal distal dilatation with a segment of normal appendix proximally and generalized appendiceal dilatation. The underlying histopathologic diagnosis for each case was assessed and categorized as neoplastic or nonneoplastic. Several additional morphologic findings were also assessed. RESULTS. Forty-nine cases with confirmed histopathologic diagnoses were identified. Of those, 20 of 23 (87.0%) cases with the finding of focal distal dilatation had an underlying neoplastic cause, whereas 14 of 26 (53.8%) cases with generalized dilatation had an underlying neoplastic cause (p = 0.012). The findings of periappendiceal fat stranding (p = 0.004), mural calcification (p = 0.006), and degree of luminal dilatation (p = 0.002) also reached statistical significance. When seen in combination with focal distal dilatation, the positive predictive value for underlying neoplasm approached or reached 100%. CONCLUSION. Our study shows that isolated focal distal appendiceal dilatation with a segment of morphologically normal appendix proximally is significantly associated with an underlying neoplastic histopathologic cause. When seen in combination with mural calcification, a diameter of more than 2 cm, and absence of periappendiceal stranding, an underlying neoplastic cause is strongly suggested.

An omental mass. Any idea?

INTRODUCTION

Pseudomyxoma extraperitonei (PE) is a rare finding. The most common cause is the rupture of a mucocele of the appendix into the retroperitoneum.

PRESENTATION OF CASE

Here we report a case of a 52 years old female patient with a mass in the right abdomen and vague lower abdominal pain underwent resection of a extraperitoneal encapsulated mass. The histopathological examination revealed a mucinous pseudomyxoma with a low grade of differentiation.

DISCUSSION

We report a case of pseudomyxoma extraperitonei with a review of literature.

CONCLUSION

The treatment of pseudomyxoma differs substantially depending on whether it is intraperitoneal or extraperitoneal. The risk of recurrence is such that follow-up, based on a physical examination, CT scan and serum markers, is essential.

Pseudomyxoma Peritonei: Presentation of Two Cases and Challenging Issues in the Literature

Pseudomyxoma peritonei (PMP) is a rather uncommon syndrome in oncology with a unique biological behavior and an estimated incidence of one to two cases per million per year. Clinically, it usually presents with a variety of unspecific signs and symptoms including abdominal pain and distention, ascites, or even bowel obstruction. Despite its intimidating clinical manifestation, PMP is characterized by satisfactory survival rates when treated with cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). We present two interesting cases of PMP deriving from the appendix with a rather atypical presentation, which was successfully treated with cytoreduction and HIPEC. In addition, we intend to raise clinical suspicion on the diagnosis of PMP and comment on several challenging issues concerning the origin and classification of PMP.

Appendiceal Neoplasms

Appendiceal neoplasms are identified in 0.9 to 1.4% of appendiceal specimens, and the incidence is increasing. It has long been professed that neuroendocrine tumors (formerly carcinoids) are the most common neoplastic process of the appendix; recent data, however, has suggested a shift in epidemiology. Our intent is to distill the complex into an algorithm, and, in doing so, enable the surgeon to seamlessly maneuver through operative decisions, treatment strategies, and patient counseling. The algorithm for evaluation and treatment is complex, often starts from the nonspecific presenting complaint of appendicitis, and relies heavily on often subtle histopathologic differences.

Analysis of Mutation and Loss of Heterozygosity by Whole-Exome Sequencing Yields Insights into Pseudomyxoma Peritonei

Pseudomyxoma peritonei (PMP) is a clinical syndrome characterized by gross mucinous ascites originating from a disseminated intraperitoneal neoplasm. Although typically confined to the abdomen, mortality is high if untreated. Biomarkers, including genetic mutation profiles, may aid treatment selection and decision making. We applied whole-exome sequencing to five patients diagnosed with low-grade appendiceal mucinous neoplasms, using paired tumor and germline samples identify biomarkers. Multiple bioinformatic approaches were applied to these data to assess both somatic mutation profiles and loss of heterozygosity events. Mutation profiles of the tumors were consistent with deamination of methylcytosine being the prevailing mechanism. Pathogenic mutations were identified in both KRAS and GNAS in all samples, and further mutations in genes implicated in PMP, namely FGFR2, APC, SMAD2, and FAT4. No TP53 somatic mutations were identified, matching expectations for low-grade tumors. Four of five samples exhibited clonal loss of heterozygosity; these regions were further examined and found to contain genes harboring pathogenic somatic mutations in some samples. RNF43 was hereby implicated in the pathogenesis of PMP of appendiceal origin, having previously been found to increase sensitivity to Wnt signaling and to have involvement in similar mucinous tumors. In conclusion, we have investigated the mutation profile of PMP of appendiceal origin and provided the first report of RNF43 involvement in its progression.

Long-Term Outcomes after Surgery for Appendiceal Mucinous Tumours

BACKGROUND

Appendiceal mucinous tumour (AMT) is a very uncommon disease. We aimed to evaluate preoperative and postoperative characteristics as well as long-term outcomes of patients with appendiceal mucinous adenomas and peritoneal pseudomyxoma (PMP).

METHODS

A consecutive cohort of patients diagnosed with AMT were included in the study. Tumour recurrence and the development of PMP was diagnosed based on the patients' complaints, physical examination, imaging studies, and biopsy results. The calculation of survival rates was performed using the Kaplan-Meier method.

RESULTS

Between January 2003 and February 2013, 25 patients had AMT. 15 patients underwent appendectomy only (60%), 5 patients (20%) right hemicolectomy, 4 patients (16%) cytoreductive surgery (CRS) ± hyperthermic intraperitoneal chemotherapy (HIPEC), and 1 patient (4%) appendectomy with caecal resection. Another 2 patients underwent CRS and HIPEC 4 days and 3 years, respectively, following initial appendectomy. In the histopathologic examination, adenoma was diagnosed in 12 patients (48%); among these, low-grade PMP was found in 1 patient (4%). Low-grade appendiceal mucinous adenocarcinoma (AMCa) was diagnosed in 11 patients (44%); among these, low-grade PMP was found in seven cases (28%) and high-grade AMCa was diagnosed in 2 patients (8%). 2 of 8 PMP patients did not undergo CRS ± HIPEC because of comorbidities. The 5-year overall survival was 100% for the adenomas and 62% for PMP patients.

CONCLUSION

AMT is a very rare entity with a considerably good outcome even in disseminated disease. CRS and HIPEC is a gold standard treatment for PMP with excellent prognosis. However, our results could still be improved in the future.