An Uncommon Multimodal Management Approach for Low-grade Appendiceal Mucinous Neoplasm With Pseudomyxoma Peritonei and Mucinous Borderline Ovarian Tumor

GNAS mutations are associated with mucin production in low-grade appendiceal mucinous neoplasms, villous adenomas, and carcinomas.

We describe four cases of pseudomyxoma peritonei (PMP) that were diagnosed and treated at our hospital.Case 1: A 26-year-old woman with a large multicystic ovarian tumor and massive ascites was diagnosed with PMP originating from a borderline mucinous ovarian tumor. She underwent fertility-preserving staging laparotomy and was treated with three courses of intraperitoneal chemotherapy. There has been no recurrence in the 15 years since her first operation. Case 2: A 72-year-old woman with a giant ovarian tumor and massive ascites was diagnosed with PMP originating from low-grade appendiceal mucinous neoplasm (LAMN). After laparotomy, the patient was managed conservatively because she did not want aggressive treatment. She has remained asymptomatic with a small amount of ascites for 3 years. Case 3: A 82-year-old woman with ovarian tumors, massive ascites, and suspected PMP underwent emergency laparotomy due to appendiceal perforation and pan-peritonitis. She was diagnosed with PMP originating from LAMN. She has remained asymptomatic with a small amount of ascites for 2 years. Case 4: A 42-year-old woman with multicystic ovarian tumors and massive ascites underwent laparotomy. She was diagnosed with PMP originating from LAMN. Since multidisciplinary treatment was indicated and desired, the patient was referred to a specialized facility where cytoreductive surgery and hyperthermic intraperitoneal chemotherapy was performed. The patient has done well since the treatment.Although most cases of PMP originate from mucinous tumors of the appendix, female patients with PMP often present with ovarian tumors and are commonly referred to gynecology clinics. It is therefore important for gynecologists to be familiar with PMP and to be able to diagnose it accurately and select the most suitable management including multidisciplinary treatments.

There is little evidence for the use of early postoperative intraperitoneal chemotherapy (EPIC) in patients with low-grade appendiceal mucinous neoplasms (LAMNs) with pseudomyxoma peritonei (PMP). This study aims to assess the outcomes regarding the use of EPIC in a large cohort of patients with LAMNs with PMP uniformly treated by cytoreductive surgery (CRS) and perioperative intraperitoneal chemotherapy (PIC), all of whom received hyperthermic intraperitoneal chemotherapy (HIPEC), and most of whom also received EPIC. This was a retrospective study of prospectively collected data of consecutive patients with peritoneal carcinomatosis of appendiceal origin who underwent CRS and PIC by one surgical team at St George Hospital in Sydney, Australia, between January 1996 and November 2015. Subgroup analyses were performed for patients with a high Peritoneal Cancer Index (PCI)>20 and also based on histopathological subtypes of LAMNs. A total of 250 patients formed the cohort of this study. No significant differences were observed in terms of hospital mortality (p=0.153), major morbidity rate (i.e., grade III/IV; p=0.593), intensive care unit stay (p=0.764), and total hospital stay (p=0.927); however, patients who received HIPEC+EPIC had a significantly longer stay in the high dependency unit. Multivariate analysis showed combined HIPEC with EPIC is an independent prognostic factor for better survival outcomes (hazard ratio 0.30, 95% confidence interval 0.12-0.74; p=0.009), adjusted for age, PCI, and histopathological subtypes. The combination of HIPEC+EPIC can provide additional survival benefits for patients with LAMNs with PMP compared with HIPEC alone, without increasing postoperative morbidity and mortality. EPIC should be considered following CRS and HIPEC for patients with LAMNs with PMP.

Non-carcinoid appendix epithelial tumors are rare. These tumors include low-grade and high-grade mucinous neoplasm also adenocarcinomas. We aimed to investigate the clinicopathological features, treatment, and risk factors of recurrence. Patients diagnosed between 2008 and 2019 were retrospectively analyzed. Categorical variables were expressed as percentages and compared using the Chi-square test or Fisher's exact tests. Overall survival and Disease-free survival of the groups were calculated by the Kaplan-Meier method, and the log-rank test was used to compare the survival rates. A total of 35 patients were included in the study. Of the patients, 19 (54%) were women and the median diagnosis age of patients was 50.4 years (19-76). As for pathological types, a total of 14 (40%) patients were mucinous adenocarcinoma and 14 (40%) patients were Low-Grade Mucinous Neoplasm (LGMN). Lymph node excision and lymph node involvement were 23 (65%) and 9 (25%) patients respectively. The majority of patients were stage 4 (27, 79%) and 25 (71%) of these patients had peritoneal metastasis. A total of 48.6% patients had been treated with cytoreductive surgery and hyper-thermic intraperitoneal chemotherapy. Median Peritoneal cancer index value was 12 (2-36). The median follow-up time was 20 (1-142) months. Recurrence developed in 12 (34%) of patients. When risk factors for recurrence are considered, there was a statistically significant difference in appendix tumors with high-grade, adenocarcinoma pathology, ones with peritoneal cancer index ≥12 and not having pseudomyxoma peritonei. Median disease-free survival was 18 (13-22, 95% CI) months. Median overall survival could not be reached while the 3-year survival rate was 79%. The risk of recurrence is higher in high-grade appendix tumors, having peritoneal cancer index ≥ 12, not having pseudomyxoma peritonei and adenocarcinoma pathology. High-grade appendix adenocarcinoma patients should be followed closely for recurrence.

Low grade appendiceal mucinous neoplasms (LAMN) are indolent tumors that lack invasive potential but may present as pseudomyxoma peritonei. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) significantly improves both overall and recurrence free survival. While systemic chemotherapy is generally considered ineffective for LAMN, little literature is available to support this notion. We evaluated outcomes for individuals with LAMN who did and did not receive systemic chemotherapy in combination with CRS+HIPEC. A multicenter retrospective cohort study was performed using the US HIPEC Collaborative that included patients with LAMN who underwent CRS+HIPEC. The overall survival (OS) and recurrence-free survival (RFS) of patients who did and did not receive systemic chemotherapy were compared. Survival and variables associated with survival were evaluated with the Kaplan-Meier analysis and cox regression, respectively. Among the 529 included patients with LAMN, 63 (11.9%) received systemic chemotherapy and CRS+HIPEC, while 466 (88.1%) were treated with only CRS+HIPEC. Patients selected for systemic chemotherapy had a higher burden of disease (mean peritoneal cancer index: 18.8 +/- 8.6 versus 14.3 +/- 8.8, p<0.001). Patients who were not treated with chemotherapy had better mean OS and RFS (OS: 104.3 +/- 6.2 months, RFS: 84.9 +/- 6.6 months) compared to those who underwent systemic chemotherapy (OS: 70.2 +/- 6.8 months, RFS: 38 +/- 5.9 months, p<0.001). Increasing pre-operative CEA level (HR 1.012, p<0.001), higher completeness of cytoreduction score (reference CCR 0, CCR2 HR 34.175, p=0.001 and CCR3 HR 52.041, p=0.001), and treatment with systemic chemotherapy (HR 4.196, p=0.045) were associated with worse OS. In this multicenter retrospective study, the receipt of perioperative chemotherapy was associated with worse long-term outcomes among patients with LAMN undergoing CRS-HIPEC. Systemic chemotherapy may lead to patient deconditioning and contribute to worse long-term outcomes. It should not be recommended outside of a clinical trial.

The classification of appendiceal mucinous tumors is controversial and terminology used for them inconsistent, particularly when they lack overtly malignant features but are associated with extra-appendiceal spread. We reviewed 107 appendiceal mucinous neoplasms and classified them as low-grade appendiceal mucinous neoplasm (LAMN) (n = 88), mucinous adenocarcinomas (MACAs) (n = 16), or discordant (n = 3) based on architectural and cytologic features. LAMNs were characterized by a villous or flat proliferation of mucinous epithelium with low-grade atypia. Thirty-nine tumors were confined to the appendix, but 49 had extra-appendiceal tumor spread, including 39 with peritoneal tumor characterized by mucin pools harboring low-grade mucinous epithelium, usually dissecting in a hyalinized stroma. Eight of the 16 MACAs lacked destructive invasion of the appendiceal wall and eight showed an infiltrative pattern of invasion. Extra-appendiceal tumor spread was present in 12 MACAs (four peritoneum, seven peritoneum and ovaries; one ovaries only). In MACAs with an infiltrative pattern, peritoneal tumor consisted of glands and single cells in a desmoplastic stroma. The peritoneal tumor in the remaining cases consisted of mucin pools that contained mucinous epithelium with high-grade atypia and, in some cases, increased cellularity compared with that seen in peritoneal spread in cases of LAMN. Three cases were classified as discordant because the appendiceal tumors were LAMNs but the peritoneal tumors were high-grade. Follow-up was available for 49 LAMNs, 15 MACAs, and 2 discordant cases. None of the patients with LAMNs confined to the appendix experienced recurrence (median follow-up 6 years). LAMNs with extra-appendiceal spread were associated with 3-, 5-, and 10-year survival rates of 100%, 86%, and 45%, respectively. Patients with MACA had 3- and 5-year survival rates of 90% and 44%, respectively (p = 0.04). The bulk of peritoneal disease correlated with prognosis among patients with MACA (p = 0.04) and, to a lesser degree, among patients with LAMNs (p = 0.07). We conclude that: 1) appendiceal mucinous neoplasms can be classified as either low-grade mucinous neoplasms or mucinous adenocarcinoma based on architectural and cytologic features; 2) tumors that can be confidently placed in the low-grade group (which requires rigorous pathologic evaluation of the appendix) and are confined to the appendix are clinically benign in our experience to date; 3) low-grade tumors confined to the appendix are morphologically identical to those with extra-appendiceal spread (except for the usual identification of breach of the wall in the latter cases) and the same designation is appropriate for the appendiceal neoplasia in each situation; 4) the long-term outlook for patients with low-grade tumors and peritoneal spread is guarded with just over half dying of disease after 10 years; 5) appendiceal mucinous tumors with destructive invasion of the appendiceal wall, complex epithelial proliferations, or high-grade nuclear atypia generally pursue an aggressive clinical course and should be classified as mucinous adenocarcinomas; 6) peritoneal tumor can be classified as involvement by LAMN or MACA, and this distinction is of prognostic significance; 7) bulky peritoneal tumor worsens prognosis; and 8) LAMNs associated with high-grade peritoneal tumor behave as adenocarcinoma.

It may be difficult to distinguish ovarian involvement by a low-grade appendiceal mucinous neoplasm (LAMN) from a primary gastrointestinal-type primary borderline (proliferative) ovarian tumor (IBMT) or an ovarian mucinous tumor arising within a teratoma, particularly when the latter is associated with mucinous ascites/pseudomyxoma peritonei. We noted that LAMNs involving the ovaries show 2 distinctive histologic features, "scalloped" glands and subepthelial stromal clefts, whereas IBMTs more often are associated with reactive cellular stroma and histiocyte aggregates (mucin granulomas). The frequency of these features was investigated in 18 LAMNs (16 with pseudomyxoma peritonei), 18 primary IBMTs, and 6 teratoma-associated mucinous tumors (selected on the basis of associated pseudomyxoma peritonei). Scalloped glands and subepithelial clefts were identified in 17 and 16 LAMNs, respectively, and in 3 and 7 IBMTs, respectively. Conversely, reactive stroma and histiocyte aggregates were present in 2 and 0 LAMNs, respectively, and in 11 and 10 IBMTs, respectively. LAMNs were often bilateral (12/18 cases) and they more frequently showed mucin dissection of the ovarian stroma and tall mucin-rich (hypermucinous) epithelial cells compared with IBMTs. Our findings suggest that scalloped glands, subepithelial clefts, cellular stroma, and histiocyte aggregates may be useful additional morphologic parameters to help distinguish these tumor types. However, teratoma-associated mucinous neoplasms can show identical histologic features to those of LAMNs involving the ovary, and therefore accurate diagnosis of such cases requires careful macroscopic and microscopic examinations of the ovaries together with complete histologic assessment of the appendix.

German S2k-guideline on diagnostics, treatment and surveillance of low-grade appendiceal mucinous neoplasms (LAMN).

Pseudomyxoma peritonei (PMP) is a rare condition usually associated with ruptured low-grade mucinous neoplasm of the appendix. Rarely, PMP can originate from mucinous adenocarcinoma of the ovary. However, the coexistence of adenocarcinoma of the endometrium and appendiceal mucinous neoplasm has not been reported. We present the case of a post-menopausal woman with endometrioid endometrial adenocarcinoma with unexpected low-grade appendiceal mucinous neoplasm and PMP.

Low-grade appendiceal mucinous neoplasms (LAMNs) are tumors that often present with widespread mucin in the peritoneal cavity (pseudomyxoma peritonei [PMP]). Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are effective treatment, but no published recommendations exist regarding surveillance. Data from prospective databases of patients who underwent CRS-HIPEC from 2001 to 2017 at two high-volume institutions were retrospectively analyzed. Patients who underwent complete CRS-HIPEC for PMP secondary to LAMN were included in the analysis. Pathologic examination confirmed the diagnosis of LAMN. Cases of mucinous adenocarcinomas and neuroendocrine tumors (goblet cell carcinoids) were excluded. The study enrolled 156 patients. The median peritoneal cancer index (PCI) was 18 (interquartile range IQR1-3, 12-23), and 125 patients (80.1%) had a CC0 cytoreduction. According to American Joint Committee on Cancer (AJCC) grading, 152 patients (97.4%) presented with acellular mucin or G1 implants, 2 patients (1.3%) presented with G2 disease, and 2 patients (1.3%) presented with G3 disease. During the follow-up period (median, 45months; IQR1-3 23-76months), 23 patients (14.7%) experienced recurrence. All the recurrences were peritoneal and occurred within 5years. The 1-, 3-, and 5-year disease-free survival (DFS) rates were respectively 95.5%, 83.4%, and 78.3%. Univariate Cox regression analysis showed that higher PCI scores (p < 0.001), a CC1 cytoreduction (p = 0.005), and higher preoperative levels of carcinoembryonic antigen (CEA) (p = 0.012) and CA-125 (p = 0.032) correlated with a shorter DFS. Only higher PCI scores independently predicted earlier recurrences (p < 0.001). Most patients had recurrence within 3years after CRS-HIPEC, and none after 5years. High PCI was the only independently significant variable. The study findings support intensive surveillance (every 3-6months) with tumor markers and imaging methods during the first 3years, and annual surveillance thereafter, with follow-up assessment after 5years yielding limited benefit.

Primary epithelial neoplasms and other epithelial lesions of the appendix (excluding carcinoid tumors)

Borderline ovarian tumors (BOTs) are epithelial ovarian neoplasms characterized by cellular proliferation and nuclear atypia without stromal invasion. On the other hand, low-grade appendiceal mucinous neoplasms (LAMNs) have features such as mucin production, a distinct invasion pattern, and low-grade cytological characteristics. Pseudomyxoma peritonei (PMP), an uncommon disorder characterized by mucinous peritoneal dispersion, can be exacerbated by both BOTs and LAMNs. We present a case of a 63-year-old patient who was diagnosed with a serous BOT, LAMN with PMP, and synchronous endometrioid endometrial cancer. After episodes of postmenopausal bleeding, an explorative curettage confirmed the diagnosis of endometrioid endometrial cancer. Since the preoperative ultrasound showed a tumorous mass in the right adnexa and retrouterine space, the patient had an explorative laparotomy. A right ovarian tumor, hepatic and omental deposits, and an appendiceal lesion were among the intraoperative findings. A hysterectomy was performed along with peritoneal biopsy, cytological analysis of peritoneal lavage, bilateral salpingo-oophorectomy, omentectomy, lymphadenectomy, and appendectomy. Histopathological examination verified the presence of BOT, LAMN with PMP, and endometrial cancer. This case highlights the diagnostic difficulties of synchronous gastrointestinal and gynecological neoplasms and emphasizes the significance of a multidisciplinary surgical approach and thorough preoperative examination. According to our knowledge, this is the first case of synchronous endometrial cancer, serous BOT, and LAMN with PMP.

Pseudomyxoma peritonei (PMP) is a rare neoplasm of the appendix, which if untreated disseminates throughout the abdominal cavity and generates considerable morbidity. Since 2002 in the UK, patients with PMP have been managed via two nationally commissioned centres. We evaluated referrals and treatment pathways over time at the Manchester centre. Data from all patients referred with suspected PMP were prospectively collected (2002-2015). Definitive treatment was cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy. Disease burden was quantified using the Peritoneal Cancer Index (PCI) (score 0-39) and complete cytoreduction (CC) defined by scores of 0/1. Novel treatment algorithms were developed for patients with low grade appendiceal mucinous neoplasm (LAMN) localized to the peri-appendiceal tissue. In all, 817 patients with confirmed PMP were referred increasing from 11 in 2002 to 103 in 2015. Disease burden was high with a mean PCI of 31 in the first quartile (Q1), levelling off to 15, 15, 17 thereafter (P=0.002). The proportion of CC0/1 increased from 67% in Q1 to 77% Q2 and 74% Q3/4. Where complete cytoreduction was achieved, 5- and 10-year overall survival was 77% and 66%. The proportion of patients referred with localized LAMN increased over time reaching 25% each year since 2010 (Ptrend <0.0001). Two-thirds of localized LAMN now undergo laparoscopically assisted risk-reducing CRS. The establishment of a national treatment centre was associated with an initial presentation of patients with advanced disease. The programme has demonstrated a clear trend over time towards earlier referral and adoption of minimally invasive techniques for localized disease.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

Low-grade appendiceal mucinous neoplasm (LAMN) is an uncommon tumor of the appendix that is usually diagnosed incidentally after surgery. Although LAMN may be asymptomatic, it can rupture and seed mucin and neoplastic epithelium into the peritoneum, causing pseudomyxoma peritonei (PMP). Data from 53 patients were retrospectively analyzed. Age, sex, tumor size, margin status, peritoneal carcinomatosis index, surgical procedures, postoperative results with histologic diagnosis, T stage, recurrence, and mortality of the patients were evaluated. Appendectomy was performed in 37 patients, right hemicolectomy in nine patients, cytoreductive surgery in one patient, and cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in six patients. Recurrence occurred in four patients. Of the patients who developed recurrence, one patient had stage T4a disease, and the other three patients had T4b disease (p<0.001). Eighteen patients had acellular mucin in the serosa and four of these patients developed recurrence (p=0.004). Twelve patients had appendix perforation, and three of these patients had PMP on exploration (p<0.001). The mean survival time was 93.3 months in patients without recurrence and 32 months in patients with recurrence (p=0.021). Low-grade appendiceal mucinous neoplasms are rare appendiceal tumors. The appropriate management of this tumor is controversial. T stage, appendix perforation, presence of acellular mucin on the serosa, and surgical margins are risk factors for the development of PMP. Appendectomy is considered sufficient when there are no risk factors for Tis (LAMN) and T3 disease. Right hemicolectomy may be sufficient if there are no risk factors for T4a disease, but cytoreductive surgery and hyperthermic intraperitoneal chemotherapy seem to be the most appropriate treatments in the presence of the stated risk factors for T4b disease.