• Cytoreductive surgery
• Hyperthermic intraperitoneal chemotherapy
• Ovarian mature teratomas
• Pseudomyxoma peritonei

• Appendiceal tumors
• Mucinous cystadenocarcinoma
• Pseudomyxoma retroperitonei
• Psoas abscess

• appendiceal mass
• conventional appendectomy
• low grade appendiceal mucinous neoplasm
• low-grade dysplasia
• rare lesions in appendix

• Case report
• Computed tomography
• Laparoscopy
• Low-grade appendiceal mucinous neoplasm
• Pseudomyxoma peritonei
• appendectomy

• Peritoneal cancer index
• Prognosis
• Pseudomyxoma peritonei
• Tomography, x-ray computed
• Ultrasonography

• Cytoreductive surgery
• Debulking
• Hyperthermic intraperitoneal chemotherapy
• Mucinous adenocarcinoma
• Treatment strategy

• Humans
• Pseudomyxoma Peritonei/diagnosis
• Peritoneal Neoplasms/diagnosis
• Cytoreduction Surgical Procedures
• Hyperthermia, Induced
• Neoplasms, Glandular and Epithelial/therapy

• Appendicular lump
• Incidental diagnosis
• Low-grade appendiceal mucinous neoplasms
• Mucocele

Low-grade appendiceal mucinous neoplasm is a tumor of the appendix whose major clinical relevance derives from its inherent potential for peritoneal dissemination as pseudomyxoma peritonei. It sometimes poses challenges in clinical, radiological, and pathological diagnosis, and it may be confused with gynecological conditions in females. We report a case of low-grade appendiceal mucinous neoplasm presenting as firm sclerotic cystic mass and was initially suspected to be an ovarian mass in a postmenopausal woman. We review the literature for the pathogenesis and clinical implication of sclerohyalinization in mucinous appendiceal tumors.

Pseudomyxoma peritonei (PMP) is a generalized term, usually known as “jelly belly” since 1884. Incidence is very low, 1–3 per million people per year. Because of its indolent nature, it is usually diagnosed at an advanced stage, thereby impacting the quality of life. The 5-year survival rate varies from 23 to 86% in world literature. Even 10 years and 20 years of survival have been described. With our experience, we like to propose rename of PMP as abdomino-peritoneal mucinous carcinoma (APM) as we strongly feel the time has come to specify the term and standardize the management strategy.

In the premier institute of India and as a tertiary referral center, we experienced the maximum number of advanced cases of APM. From 2012 to 2021, we analyzed all the APM patients based on a prospectively maintained computerized database in the department of surgical oncology and found the reasons for renaming from this traditional one.

We included a total of 87 patients who underwent surgical intervention. Thirty-five patients underwent cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), and 52 patients underwent debulking. In CRS-HIPEC patients, CC-0 was achieved in 28 patients (80%), CC-1 in 4 patients (11.4%), and CC-2 in 3 patients (8.6%). Palliative intent HIPEC was done in 3 patients (8.6%). Clavien-Dindo grade III and IV morbidity was observed in 18.8% of patients with 90 days mortality of 5.7%.

With our long-term experience and advancement of scientific evidence, we like to propose a new name for PMP as APM. We strongly believe this paper will give a clear picture of this rare disease and standard management outlines.

• Abdomino-peritoneal mucinous carcinoma (APM)
• Appendicular neoplasm
• Cytoreductive surgery (CRS)
• Hyperthermic intraperitoneal chemotherapy (HIPEC)
• Pseudomyxoma peritonei (PMP)

Appendiceal mucinous neoplasm (AMN) is a rare obstructive dilatation of the appendix caused by an intraluminal accumulation of mucoid material, showing an insidious onset and few specific clinical manifestations. The purpose of the study is to analyze clinicopathological characteristics of primary AMN and recurrence after radical resection.

A total of 50 patients were included in the retrospective cohort study of AMN. Patient data, such as demographics, tumor characteristics, surgical management, preoperative serum carcinoembryonic antigen (CEA), and carcinoembryonic antigen 19-9 (CA19-9) levels, were collected. All patients were followed-up with interval CT scans until the end of December 2021, with overall survival (OS) and progression-free survival (PFS) being calculated.

All patients were confirmed as AMN by pathological diagnosis after surgery, including 28 cases (56.00%) of low-grade AMN (LAMN) and 22 cases (44.00%) of non-LAMN. Among 50 patients with AMN, there were 12 cases (24.00%) complicated with pseudomyxoma peritonei (PMP). Higher proportions of patients with pTis, pT3, pT4a, ruptured at presentation, and PMP were found in patients with non-LAMN patients than LAMN (p < 0.05). There was a remarkable difference about preoperative serum CA19-9 levels between patients with LAMN and non-LAMN (p = 0.044). Patients complicated with PMP had a higher proportion of patients with ruptured at presentation than those who were not (p < 0.001). The patients with PMP had increased tumor size compared with those without PMP (p = 0.031). Remarkable differences were observed in terms of preoperative serum CA19-9 (p = 0.009) levels between patients with PMP and without PMP. We performed a multivariate analysis of the presence or absence of PMP and found that ruptured at presentation was found to be a risk factor for PMP in patients with AMN (p = 0.003). The PFS in the patients with PMP and those without was 33.33% (4/12) and 2.63% (1/38), showing a significant difference (P = 0.002).

The study demonstrates that ruptured at presentation and PMP may influence the prognosis and survival of patients with AMN.

• National Natural Science Foundation of China

• Biomarkers
• Low-grade appendiceal mucinous neoplasm
• Pseudomyxoma peritonei
• Tumor

The differential diagnosis of abdominal pain is wide as both benign and malignant pathologies must be considered. There are currently no published case reports of low-grade appendiceal mucinous neoplasms (LAMNs) mimicking perforated diverticulitis. LAMNs are a heterogenous group of tumours, with no consensus treatment algorithm based on stage and histology. In this case report, we discuss a patient who presented emergently with generalized peritonism, with a diagnosis of perforated diverticulitis made on computed tomography scan. At laparotomy, a perforated appendix was identified, with histopathology identifying a perforated LAMN. This case highlights the importance of considering this rare but increasing incidence tumour when operative management is being planned.

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

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.

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.

• Appendiceal mucinous neoplasm
• Diagnosis
• Cystic mass
• Pelvic cavity
• Appendectomy
• Case report

• Cancers of Dispensable Organs (CAD)
• Cancers of Unknown Primary (CUP)
• Cell of cancer origin
• Metastasis of Unknown Origin (MUO)
• Pseudomyxoma Peritonei

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).

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.

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.

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.

• prognosis
• pseudomyxoma peritonei
• recurrence
• sonography
• ultrasound

Although the understanding of appendiceal mucinous neoplasms (AMNs) and their relationship with disseminated peritoneal mucinous disease have advanced, the diagnosis, classification, and treatment of AMNs are still confusing for pathologists and clinicians. The Gastrointestinal Pathology Study Group of the Korean Society of Pathologists (GPSG-KSP) proposed a multicenter study and held a workshop for the “Standardization of the Pathologic Diagnosis of the Appendiceal Mucinous Neoplasm” to overcome the controversy and potential conflicts. The present article is focused on the diagnostic criteria, terminologies, tumor grading, pathologic staging, biologic behavior, treatment, and prognosis of AMNs and disseminated peritoneal mucinous disease. In addition, GPSG-KSP proposes a checklist of standard data elements of appendiceal epithelial neoplasms to standardize pathologic diagnosis. We hope the present article will provide pathologists with updated knowledge on how to handle and diagnose AMNs and disseminated peritoneal mucinous disease.

• Appendiceal mucinous neoplasm
• Disseminated peritoneal mucinous disease
• Pathologic diagnosis
• Standardization

Low-Grade Appendiceal Mucinous Neoplasms (LAMN) are noninvasive epithelial tumors of the appendix. Symptomatology is unspecific and can simulate appendicitis. The multidisciplinary approach for the correct diagnosis and management of this kind of tumor is important, as the prognosis depends on it.

A 70-years-old man with an appendiceal picture is presented. McBurney and Blumberg's signs were found and the Echography has reported an acute appendicitis. He underwent laparoscopic surgery, founding a Tumor in the Cecum of 10 × 5 cm. We decided to perform an appendectomy with a total cecectomy. The pathological diagnosis was a LAMN. Ten months later, a Computed Tomography (CT) Scan control was performed reporting no evidence of Tumoral activity or Distance Metastasis, neither pseudomyxoma peritonei (PMP) evidence.

LAMN has been a very controversial tumor. The definitive management is appendectomy. There are controversies about the laparoscopic and open approach, and when there are positive margins. The stage was a pTis (LAMN) pNx according to the 8th edition of the American Joint Committee on Cancer (AJCC). The prognosis depends on the tumoral stage and the presence of PMP. In our case, we have performed a CT scan follow up and there was no Tumoral activity or Distance Metastasis, neither PMP evidence.

LAMN is a very interesting and rare tumor. The diagnosis of this case was a real challenge. Our management was simple due to the tumoral stage. Pathology played a very important role in treatment and prognosis.

•

The clinical presentation of LAMN is unspecific, it can simulate an appendicitis.

• Appendiceal tumor
• Case report
• LAMN
• Mucinous neoplasm
• Pseudomyxoma peritonei

Appendiceal tumors are rare lesions that may not be easily differentiated from primary ovarian lesions preoperatively, despite the use of advanced diagnostic methods by experienced clinicians.

A 59-year-old G2P2 woman, with chronic pelvic pain, underwent a pelvic ultrasound that revealed an adnexal mass measuring 58 mm × 34 mm × 36 mm, with irregular borders, heterogeneous echogenicity, no color Doppler vascularization and without acoustic shadowing. Normal ovarian tissue was visualized in contact with the lesion, and it was impossible to separate the lesion from the ovary by applying pressure with the ultrasound probe. Ascites, peritoneal metastases or other alterations were not observed. With the international ovarian tumor analysis ADNEX model, the lesion was classified as a malignant tumor (the risk of malignancy was 27.1%, corresponding to Ovarian-Adnexal Reporting Data System category 4). Magnetic resonance imaging confirmed the presence of a right adnexal mass, apparently an ovarian tumor measuring 65 mm × 35 mm, without signs of invasive or metastatic disease. During explorative laparotomy, normal morphology of the internal reproductive organs was noted. A solid mobile lesion involved the entire appendix. Appendectomy was performed. Inspection of the abdominal cavity revealed no signs of malignant dissemination. Histopathologically, the appendiceal lesion corresponded to a completely resected low-grade mucinous appendiceal neoplasm (LAMN).

The appropriate treatment and team of specialists who should provide health care to patients with seemingly adnexal lesions depend on the nature (benign vs malignant) and origin (gynecological vs nongynecological) of the lesion. Radiologists, gynecologists and other pelvic surgeons should be familiar with the imaging signs of LAMN whose clinical presentation is silent or nonspecific. The assistance of a consultant specializing in intestinal tumors is important support that gynecological surgeons can receive during the operation to offer the patient with intestinal pathology an optimal intervention.

• Adnexal mass
• Appendiceal neoplasm
• Diagnostic imaging
• Pelvic neoplasm
• Adnexal diseases
• Pelvic neoplasm
• Case report

• appendix cancer
• genetic analysis
• hyperthermic intraperitoneal chemotherapy
• next‐generation sequencing
• pseudomyxoma peritonei

• abscess cavity drainage
• acute appendicitis
• cecum resection
• mucinous tumor

Mucinous neoplasms of appendix account for 0.2–0.4% of all the appendix specimens. The occurrence of this neoplasm in pregnancy is extremely rare. We describe a case of a pregnant lady who was diagnosed as acute appendicitis and found to have Low-Grade Mucinous neoplasm on histopathology. In the existent literature, there are only a few such cases reported and none from our Middle East region.

42-year-old pregnant lady at 24 weeks of gestation presented with classical symptoms of acute appendicitis. She had leukocytosis but the Ultrasound was equivocal. She underwent laparoscopic appendectomy and found to have an inflamed appendix. Postoperative recovery was satisfactory and was discharged home. The histopathology report showed low-grade mucinous neoplasm of the appendix and she was detailed about it on follow up.

The incidence of appendiceal neoplasm is rare in routine appendectomy and carcinoid is the most common tumor of the appendix. Low-Grade mucinous neoplasm is a rare entity and its presence in pregnancy is further rarer.

Since this neoplasm does not manifest with a characteristic clinical profile it is difficult to diagnose, even with extensive preoperative evaluation. Although surgical treatment is straight forward, the management of the appendiceal neoplasm during pregnancy necessitates full knowledge of the natural history of the disease to attain equilibrium of concern for maternal survival and fetal health.

•

Mucinous neoplasms of appendix are known to be rarely found in all the appendix specimens, but the occurrence of this neoplasm in pregnancy is extremely rare.

• Acute abdomen
• Appendicitis
• Case report
• Mucinous cancer
• Pregnant

During the microscopic examination of the specimens after appendectomy operations performed due to acute appendicitis, pathologists may encounter some incidental and unusual lesions. Appendectomy specimens are sampled as 3 sections/1 paraffin block in many centers. In this study, we aimed to evaluate whether multiple and dense sampling of appendix specimens has an impact on the incidence of incidental lesions of the appendix.

This study is a retrospective study of 1154 patients who underwent appendectomy with presumed acute appendicitis at the Department of General Surgery, Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine, had histopathological evaluation between 2007–2011 and 2014–2018. Group 1 was made up of the patients whose appendix specimens were examined as 3 sections/1 paraffin block. Group 2 was made up of the patients whose appendix specimens were sampled completely. In this study, it was evaluated whether there was a difference between the two groups concerning incidence of incidental benign and malign appendix lesions.

There were 579 patients in Group 1, 575 patients in Group 2, and the mean age of the groups was 26 and 28, respectively. Neither acute appendicitis findings nor any of the other unusual lesions were found in 57 specimens (9.8%) in Group 1 and 58 specimens (10.1%) in Group 2. Unusual pathological findings were detected in six specimens in Group 1 and 21 in Group 2. All unusual lesions, including benign and malignant, were significantly higher in Group 2 than in Group 1 (p=0.013). Concerning the incidence of malignant incidental lesions alone, there was no significant difference between the two groups (p=0.136).

Multiple and dense sampling of appendectomy specimens increases the likelihood of detecting unusual lesions of the appendix.

• Acute appendicitis
• incidental lesions
• multiple and dense sampling

• Appendectomy
• appendiceal malignancies
• appendiceal tumors
• appendicitis

To investigate the clinical and pathological characteristics of appendiceal mucinous adenocarcinoma with peritoneal metastasis and analyze the prognostic factors.

A retrospective analyses of clinicopathological features of 50 patients with appendiceal mucinous adenocarcinoma with peritoneal metastasis from January, 2013 to December, 2017 in Aerospace Central Hospital, Beijing, China. Survival data calculation and comparison were respectively performed with the Kaplan-Meier method and the log-rank test. The Cox proportional hazards regression method was used for multivariate survival analyses.

Cytoreduction for appendiceal mucinous adenocarcinoma was conducted on 50 patients (24 males and 26 females), with a median age of 52.5 years at the time of surgery (range 31–71 years). The median overall survival (OS) time was 24 months, with 2-,3- and 5-year survival rates of 53, 24 and 8%, respectively. At the last follow-up in December 2018, 13 patients were still alive. Multivariate analysis revealed that patients who had low Ki-67 expression (less than 50%) and CCR (completeness of cytoreduction) 0/1/2 score had significantly better OS rate than their respective counterparts.

Ki-67 expression statue and CCR score could be employed as the prognosis prediction in patients with appendiceal mucinous adenocarcinoma.

• Appendiceal mucinous adenocarcinoma
• Completeness of cytoreduction score
• Prognosis
• Pseudomyxoma peritonei

• Appendectomy
• appendiceal malignancies
• appendiceal tumors
• appendicitis

Pseudomyxoma peritonei (PMP) is a rare benign, but progressive, disease according to myxoma histopathology. Surgical resection is the preferred and most effective treatment, but the outcomes are often unsatisfactory.

A 63-year-old Chinese woman with PMP received apatinib at a daily dose of 0.5 mg for 15 d per cycle and at a daily dose of 0.4 mg to date for recurrent abdominal distension after surgical treatment and hyperthermic intraperitoneal chemotherapy. During the follow-up period, apatinib was the maintenance treatment with a progression-free period of 10 mo and the toxicity of apatinib was controllable and tolerable. Unfortunately, recurrence occurred 10 mo after administration. After two operations, the patient gave up treatment at the 18^th mo and eventually died of intestinal obstruction and multiple organ failure.

Apatinib may be an option for recurrent PMP after surgical treatment, but this conclusion remains to be confirmed.

• Pseudomyxoma peritonei
• Abdominal distention
• Anti-angiogenic agent
• Apatini
• Case report

Pseudomyxoma peritonei (PMP) is a rare and life-threatening cancer of the abdominal peritoneum. Symptoms can be non-specific and ignorable for several years such that most cases are diagnosed during explorative surgery. The cornerstones of diagnosis and effective management are heightened awareness and clinical suspicion, timely recognition, and early referral to a specialist center for work-up and cytoreductive surgery. We report an interesting case of a patient with PMP who had successful cytoreductive surgery and heated intraperitoneal chemotherapy.

• ascites
• cytoreductive surgery
• pseudomyxoma peritonei
• tumor markers

Low-grade appendiceal mucinous neoplasm (LAMN) is a rare malignancy with symptoms varying depending on the clinical manifestations. The most worrisome complication of this particular neoplasm is seeding of mucin into the adjacent peritoneum leading to pseudomyxoma peritonei (PMP). There is a lack of standardized treatment approach; however, an appendectomy-only approach is currently being used for the resection of non-metastatic disease. We present an unusual case of a 67-year-old male found to have LAMN status post elective appendectomy, six months after being treated for an appendiceal abscess.

• appendix
• low-grade appendiceal mucinous neoplasm
• mucin
• pseudomyxoma peritonei

Le pseudo myxome péritonéal (PMP), est un syndrome clinicopathologique caractérisé par une ascite mucineuse et des pools de mucine comportant un épithélium mucineux néoplasique dans la cavité péritonéale. Le PMP est peu fréquent, et se présente avec des manifestations cliniques et pathologiques inhabituelles posant des problèmes diagnostic et thérapeutiques. L'atteinte des viscères abdominaux et les métastases ganglionnaires sont rares et se limitent à des cas sporadiques rapportes dans la littérature. Nous rapportons ici le cas d'un patient de 56 ans opéré à deux reprises pour PMP d'origine appendiculaire, et qui a consulté pour douleurs abdominales évolutives, cinque ans après sa dernière cure. Le scanner avait objective une récidive de pseudo myxome péritonéal, avec présence de lésions intraparenchymateuses spléniques et hépatique .l 'étude anatomopathologique avait objective la récidive d'un pseudo myxome péritonéal de bas grade avec la localisation intrasplénique et hépatique des mêmes lésions histologiques confirmant les métastases.

• Acute appendicitis
• Histopathological classification
• LMANs
• MACAs
• Mucinous appendiceal tumors
• Pseudomyxoma peritonei

• SEER database
• gastrointestinal mucinous adenocarcinoma
• incidence
• survival

• Appendix
• Cytoreductive surgery
• Hyperthermic intraperitoneal chemotherapy
• Mucocele
• Pseudomyxoma peritonei

Mucinous neoplasm of the appendix are rare entities, among these, mucinous cystadenomas contribute to 31–34%. Cystadenomas often produce extensive dilatation of the appendix with epithelial atypia. Spontaneous perforation often occurs in 20%, leading to mucin distribution throughout the peritoneal cavity. Half of the patients are completely asymptomatic and are detected as an incidental diagnosis, others symptoms include a palpable mass, hernias, weight loss, peritonism or even intestinal obstruction. We present a case of a 71-year-old female, she presented with a palpable mass in the upper abdomen. A ventral hernia was the most likely diagnosis and hernioplasty was planned. At surgery, a mucinous mass was discovered and mucous material was found free en the peritoneal cavity. Also, a perforated appendix and a mass in the cecum was found. Patient underwent full recovery. Pathology reported pseudomyxoma peritonei as the final diagnosis.

• Appendicular mucocele
• appendicular mucinous adenocarcinoma
• appendicular mucinous cystadenocarcinoma
• appendicular mucinous cystadenoma
• low-grade appendiceal mucinous neoplasms
• mucinous neoplasms of the appendix
• pseudomyxoma peritonei

• Adult
• Appendiceal Neoplasms/diagnosis
• Appendiceal Neoplasms/pathology
• Appendix/pathology
• Botswana
• Cecal Diseases/diagnosis
• Cecal Diseases/surgery
• Colectomy/methods
• Female
• Humans
• Laparotomy/methods
• Mucocele/diagnosis
• Mucocele/surgery
• Tomography, X-Ray Computed
• Ultrasonography

Malignant tumours of the appendix are quite rare, especially appendiceal adenocarcinomas, which may be difficult to detect preoperatively or intraoperatively. We collected data for 1404 patients with adenocarcinoma of the appendix from the Surveillance, Epidemiology, and End Results Program (SEER) database to explore the potential associations between clinicopathological factors and overall survival. Furthermore, a novel nomogram for predicting prognosis was developed based on our analysis of the SEER data. The nomogram prediction model included seven prognostic factors derived based on different clinical estimates. When compared with the traditional tumour-node-metastasis (TNM) staging system, the nomogram prediction model showed superior discriminatory power (Harrell’s C-index, 0.741 vs. 0.686) and a greater degree of similarity to actual 5-year overall survival after calibration (Akaike Information Criterion index, 5270.781 vs. 5430.141). Finally, we provide recommendations for the management of patients with adenocarcinoma of the appendix. Notably, we found the depth of adenocarcinoma invasion may be used as an indicator to determine the optimal surgical approach. For mucinous adenocarcinomas of the appendix, because these tumours are characterized by unique biological behaviour, intraoperative hyperthermic intraperitoneal chemotherapy (HIPEC) is recommended. However, whether systematic chemotherapy should be administered to patients with adenocarcinoma of the appendix requires further investigation.

A 68-year-old man presented with progressive right lower quadrant abdominal pain and tenderness without rebound tenderness, and with constipation during the prior 9 mo. Abdomino-pelvic computed tomography and magnetic resonance imaging demonstrated a dilated appendix forming a fistula to the sigmoid colon. Open laparotomy revealed a bulky abdominal tumor involving appendix, cecum, and sigmoid, and extending up to adjacent viscera, without ascites or peritoneal implants. The abdominal mass was removed en bloc, including resection of sigmoid colon, cecum (with preservation of ileocecal valve), appendix, right vas deferens, testicular vessels, and minimal amounts of anterior abdominal wall; and shaving off of small parts of the walls of the urinary bladder and small bowel. Gross and microscopic pathologic examination revealed an appendix-to-sigmoid malignant fistula secondary to perforation of mucinous adenocarcinoma of the appendix with minimal local spread (stage T4). However, the surgical margins were clear, all 13 resected lymph nodes were cancer-free, and pseudomyxoma peritonei or peritoneal implants were not present. The patient did well during 1 year of follow-up with no clinical or radiologic evidence of local recurrence, metastases, or pseudomyxoma peritonei despite presenting with extensive stage T4 cancer that was debulked without administering chemotherapy, and despite presenting with malignant appendiceal perforation. This case illustrates the non-aggressive biologic behavior of this low-grade malignancy. The fistula may have prevented free spillage of cancerous cells and consequent distant metastases by containing the appendiceal contents largely within the colon.

• Mucinous adenocarcinoma
• Appendicitis
• Appendix
• Malignant fistula
• Pseudomyxoma peritonei
• Colon cancer
• Metastases

• Adenocarcinoma/diagnostic imaging
• Adenocarcinoma/pathology
• Adenocarcinoma/surgery
• Aged
• Appendiceal Neoplasms/diagnostic imaging
• Appendiceal Neoplasms/pathology
• Appendiceal Neoplasms/surgery
• Appendix/diagnostic imaging
• Appendix/surgery
• Colon, Sigmoid/diagnostic imaging
• Colon, Sigmoid/pathology
• Colon, Sigmoid/surgery
• Fistula/diagnostic imaging
• Fistula/pathology
• Fistula/surgery
• Humans
• Laparotomy
• Magnetic Resonance Imaging
• Male
• Neoplasm Metastasis
• Neoplasm Recurrence, Local
• Tomography, X-Ray Computed