Mucocoele of the appendix.

Introduction: Mucocoele of the appendix occurs in 0.2-0.7% of people in the world without any well-defined clinical symptoms. It occurs when there is an accumulation of mucous in the lumen of the appendix. Case Presentation: We present three cases: a 48-year-old male admitted to the emergency room with a one-day history of right iliac fossa pain. Abdominal examination was suggestive of acute appendicitis. The initial abdominal computerised tomography scan was reported as being unremarkable. At surgery, a firm tumour of the appendix was found, and a limited right hemicolectomy was done. Histopathology confirmed a mucocoele of the appendix with borderline mucinous histology.The second case is a 63-year-old man who presented with a one-year history of abdominal distension and weight loss. Previous abdominal ultrasound was suggestive of liver cirrhosis with significant ascitic fluid. Abdominal magnetic resonance imaging found an appendix mucocoele with infiltration of the omentum and scalloping of the liver surface suggestive of pseudomyxoma peritonei. A percutaneous biopsy of the omental mass confirmed metastatic mucinous adenocarcinoma of the appendix.The third case is a 68-year-old man who, during an annual medical check-up, had an incidental finding of a cystic right iliac fossa mass on ultrasound, confirmed on abdominopelvic computerised tomography scan to be an appendix mucocele. He had laparoscopic appendicectomy. The histopathological diagnosis confirmed a mucinous cystadenoma of the appendix. Conclusion: Preoperative diagnosis of appendiceal mucocoele is difficult and commonly discovered intraoperatively. The prognosis is good for the histologically benign type, but it is poor when malignant or peritoneal lesions are present. Funding: None declared.

What is the optimum post treatment surveillance imaging protocol for low-grade appendiceal mucinous neoplasms and pseudomyxoma peritoneii?

Appendiceal mucinous neoplasms are rare and can be associated with the development of disseminated peritoneal disease known as pseudomyxoma peritonei (PMP). Mucinous tumours identified on appendicectomy are therefore followed up to assess for recurrence and the development of PMP. In addition, individuals who initially present with PMP and are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) are followed up to assess for recurrence. However, despite the concerted efforts of multiple expert groups, the optimal imaging follow-up protocol is yet to be established. The purpose of this article is to review the available evidence for imaging surveillance in these populations to identify the optimum post-resection imaging follow-up protocol.

Superiority of 18F-FAPI-42 PET/CT in the detection of primary tumor and management of appendiceal neoplasm to 18F-FDG PET/CT and CE-CT.

BACKGROUND: In the present study, we investigated the value of 18F-fibroblast-activation protein inhibitor (FAPI) positron emission tomography/computed tomography (18F-FAPI-42 PET/CT) to preoperative evaluations of appendiceal neoplasms and management for patients. METHODS: This single-center retrospective clinical study, including 16 untreated and 6 treated patients, was performed from January 2022 to May 2023 at Southern Medical University Nanfang Hospital. Histopathologic examination and imaging follow-up served as the reference standard. 18F-FAPI-42 PET/CT was compared to 18F-fluorodeoxyglucose (18F-FDG) PET/CT and contrast-enhanced CT (CE-CT) in terms of maximal standardized uptake value (SUVmax), diagnostic efficacy and impact on treatment decisions. RESULTS: The accurate detection of primary tumors and peritoneal metastases were improved from 28.6% (4/14) and 50% (8/16) for CE-CT, and 43.8% (7/16) and 85.0% (17/20) for 18F-FDG PET/CT, to 87.5% (14/16) and 100% (20/20) for 18F-FAPI-42 PET/CT. Compared to 18F-FDG PET/CT, 18F-FAPI-42 PET/CT detected more regions infiltrated by peritoneal metastases (108 vs. 43), thus produced a higher peritoneal cancer index (PCI) score (median PCI: 12 vs. 5, P < 0.01). 18F-FAPI-42 PET/CT changed the intended treatment plans in 35.7% (5/14) of patients compared to CE-CT and 25% (4/16) of patients compared to 18F-FDG PET/CT but did not improve the management of patients with recurrent tumors. CONCLUSIONS: The present study revealed that 18F-FAPI-42 PET/CT can supplement CE-CT and 18F-FDG PET/CT to provide a more accurate detection of appendiceal neoplasms and improved treatment decision making for patients.

Nodular image in the appendix observed on ultrasound: endometriosis or neuroendocrine neoplasia?

Objective: To evaluate the association between clinical and imaging with surgical and pathological findings in patients with suspected neuroendocrine tumor of appendix and/or appendix endometriosis. Methods: Retrospective descriptive study conducted at the Teaching and Research Institute of Hospital Israelita Albert Einstein, in which medical records and databases of patients with suspected neuroendocrine tumor of appendix and/or endometriosis of appendix were analyzed by imaging. Results: Twenty-eight patients were included, all of which had some type of appendix alteration on the ultrasound examination. The pathological outcome of the appendix found 25 (89.3%) lesions compatible with endometriosis and three (10.7%) neuroendocrine tumors. The clinical findings of imaging and surgery were compared with the result of pathological anatomy by means of relative frequency. Conclusion: It was possible to observe a higher prevalence of appendix endometriosis when the patient presented more intense pain symptoms. The image observed on ultrasound obtained a high positive predictive value for appendicular endometriosis.

Prospective pilot study utilizing changes in quantitative values obtained on serial fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) in dogs with appendicular osteosarcoma before and after stereotactic body radiation therapy (SBRT) and carboplatin chemotherapy to assess for prediction of survival and therapeutic effectiveness.

Serial fluorine 18 fluorodeoxyglucose (18F-FDG) positron emission tomography-CT (PET/CT) is commonly used in human oncology to prognosticate and evaluate for therapeutic effectiveness. In this pilot study, dogs with naturally occurring appendicular osteosarcoma were evaluated with serial 18F-FDG PET/CT in an attempt to assess for response to therapy, prognostic factors, and appropriateness of imaging intervals. Fourteen dogs were enrolled in the trial. All dogs had the initial 18F-FDG PET/CT (PET1), with nine dogs having their end-of-therapy 18F-FDG PET/CT (EoT PET) 3 months after stereotactic body radiation therapy (SBRT) to the primary tumor. The median percent change from the PET1 to the EoT PET for the standard uptake value maximum (SUVmax%) was -58% (range: -17 to -88%), metabolic tumor volume (MTV%) was -99.8% (range: -65 to -100%), and total lesion glycolysis (TLG%) was -99.8% (range: -75 to -100%), all of which were significant (P < .05, <.05, and <.05, respectively). On evaluation, it was found that volumes of GTV and CTV were significant for survival (P < .05 and <.05), MTV1, TLG1, and SUVmax on the EoT PET (SUVmaxEoT) were predictive of metastasis (P < .05), and the SUVmax% was significantly correlated to the time to first event (P < .05). Based on this data, serial 18F-FDG PET/CT performed 3 months after SBRT can show a significant reduction in avidity, and the quantitative data collected may help predict metastatic disease in canine appendicular osteosarcoma.

Low-grade Appendiceal Mucinous Neoplasm with Appendiceal Reduction and Re-expansion Over a Two-year Period.

A 71-year-old woman was found to have submucosal tumor-like lesion on colonoscopy (CS) before gastric surgery, and computed tomography (CT) showed a 12-mm structure at the base of the appendix. The lesion could not be clearly detected on CT nine months later, but it had enlarged again on CT one year later; therefore, CS and endoscopic ultrasound (EUS) were performed. The lesion was determined to be cystic with viscous contents, and laparoscopic appendicectomy was performed. This is the first report of low-grade appendiceal mucinous neoplasm (LAMN) diagnosed by a histopathologic examination of a resected specimen showing shrinkage and re-expansion of the appendix.

The appendix "mucocoele" misnomer: radiological terminology of "likely appendix mucinous neoplasm" better reflects pathology findings.

AIM: To review the radiological terminology used to describe dilated mucin-containing appendiceal lesions with correlation to the histopathological diagnosis. MATERIALS AND METHODS: Radiology and histopathology reports for all patients with an abnormally dilated appendix referred to a tertiary peritoneal malignancy centre, between January 2021 and December 2021, were reviewed. RESULTS: Overall, 213 patients were included with a median appendiceal diameter of 25.5 mm (range 10-125 mm). Peritoneal disease was present in 109 patients, with the remaining 104 cases demonstrating a dilated appendix only. Local radiology reports were available for 201 cases with the appendix described in 168 cases as appendiceal mucocoele (n=104), appendiceal neoplasm (n=40), appendicitis (n=18), and dilated appendix (n=6). The appendix was not mentioned in 33/201 (15%), either misinterpreted as other pathology (n=15) or not reported (n=18). Peritoneal malignancy histopathology reports were available in 188 cases and reported as low-grade appendix mucinous neoplasm (LAMN, n=144), high-grade appendix mucinous neoplasm (HAMN, n=13), LAMN with foci of HAMN (n=2), LAMN with neuroendocrine tumour (n=2), LAMN with goblet cell adenocarcinoma (n=1), goblet cell adenocarcinoma (n=8), mucinous adenocarcinoma (n=14), non-mucinous adenocarcinoma (n=1), and benign histology (n=3). Only one case of a true inflammatory "mucocoele"/retention cyst was reported. CONCLUSION: In this cohort of patients, the overwhelming majority of dilated, mucin-filled appendices contained malignant cells and benign mucin-filled appendices were rare. The present authors advocate that the term "likely appendix mucinous neoplasm" should replace "appendix mucocoele" to represent the most likely pathology and facilitate less ambiguous interpretation in management decisions.

Appendiceal schwannoma - report of a case and literature review.

Appendiceal tumours encompass a wide spectrum of differential diagnoses and frequently present with clinical features of appendicitis. We report the case of a 43-year-old woman who presented with epigastric pain, dyspepsia and bloating. An atypical right para-iliac mass was detected on abdominal ultrasound, and computed tomography (CT) identified an appendiceal tumour. The tumour subtype remained indeterminate following Gallium-68 Dotatate positron emission tomography (PET); however, an appendiceal neuroendocrine tumour was suspected. Surgical resection with laparoscopic en bloc appendicectomy and limited caecectomy was performed, and histopathological assessment confirmed an appendiceal schwannoma. The report is followed by a review of the literature. To our knowledge, there have been fourteen reported cases of appendiceal schwannoma. The preoperative diagnosis can be challenging and appendiceal schwannoma had not been suspected in any of the reported cases, while a suspected diagnosis of neuroendocrine tumour or gastrointestinal stromal tumour was common. Definitive diagnosis requires immunohistochemical assessment and S100 is the hallmark. No personal or family history of underlying neurofibromatosis (NF) type 1 or type 2 has been reported to date. As for other gastrointestinal schwannomas, complete surgical resection is the recommended treatment for appendiceal schwannoma. Following this, despite lack of long-term follow-up, no cases of recurrence have been reported thus far.

Appendiceal Incidentalomas: Prevalence, Radiographic Characteristics, Management, and Outcomes.

BACKGROUND: Radiographically detected incidental appendiceal abnormalities, in this report termed "appendiceal incidentalomas" (AIs), are an ill-defined entity with an unknown prevalence of neoplasm. This study aimed to describe the prevalence, radiographic characteristics, and outcomes of patients with a diagnosis of AI. METHODS: The study reviewed the electronic health records for patients at a single institution undergoing abdominopelvic computed tomography and magnetic resonance imaging (MRI) from 2000 to 2020 for non-appendix-related complaints with mention of appendix abnormality in the radiology report. The suggested diagnosis at the index imaging was recorded. Outcomes were compared between the operative and non-operative patients. RESULTS: Of 5197 records, 484 were identified as reports of AIs (9 % of screened patients). Neoplasms were suggested radiographically in 16 % (n = 79) of the records, 59 % (47/79) of which were resected. Pathologically, 32 of the abnormalities were confirmed as neoplasms, yielding a diagnostic accuracy of 68 %. Compared with the non-operative patients, the operative patients had AIs with a larger mean diameter (22.7 ± 13.0 vs. 17.8 ±7.7 mm; p = 0.04), a higher colonoscopy rate (51 % vs. 22 %; p = 0.01), and diagnosis at a younger age (55.8 ± 15.6 vs. 67.2 ± 16.0 years; p = 0.003). The postoperative complications were minor (Clavien-Dindo grade 1 or 2) in 26 % and major (grades 3-5) in 4 % of the cases. During a median follow-up period of 28.3 months, 94 % of the patients were alive without disease, and 6 % died of other causes. The 32 non-operative suggested neoplastic AIs had a median follow-up period of 20.9 months. At this writing, 59 % of the operative patients are alive with a stable abnormal appendix, 13 % had no appendix abnormality at last follow-up visit, and 28 % have died of other causes. CONCLUSION: Neoplastic AIs are an uncommon finding and radiographically diagnosed with relatively high accuracy. Larger appendiceal diameter and younger age predict operative intervention. Although surgery is associated with favorable outcomes and minimal risk of postoperative complications, observation of suspected neoplastic AIs may be a safe alternative for select patients undergoing follow-up longitudinal imaging.

Management of incidentally discovered appendiceal neuroendocrine tumors after an appendicectomy.

Appendiceal neuroendocrine tumors (aNETs) are an uncommon neoplasm that is relatively indolent in most cases. They are typically diagnosed in younger patients than other neuroendocrine tumors and are often an incidental finding after an appendectomy. Although there are numerous clinical practice guidelines on management of aNETs, there is continues to be a dearth of evidence on optimal treatment. Management of these tumors is stratified according to risk of locoregional and distant metastasis. However, there is a lack of consensus regarding tumors that measure 1-2 cm. In these cases, some histopathological features such as size, tumor grade, presence of lymphovascular invasion, or mesoappendix infiltration must also be considered. Computed tomography or magnetic resonance imaging scans are recommended for evaluating the presence of additional disease, except in the case of tumors smaller than 1 cm without additional risk factors. Somatostatin receptor scintigraphy or positron emission tomography with computed tomography should be considered in cases with suspected residual or distant disease. The main point of controversy is the indication for performing a completion right hemicolectomy after an initial appendectomy, based on the risk of lymph node metastases. The main factor considered is tumor size and 2 cm is the most common threshold for indicating a colectomy. Other factors such as mesoappendix infiltration, lymphovascular invasion, or tumor grade may also be considered. On the other hand, potential complications, and decreased quality of life after a hemicolectomy as well as the lack of evidence on benefits in terms of survival must be taken into consideration. In this review, we present data regarding the current indications, outcomes, and benefits of a colectomy.

Multiple intestinal hemangioma concurrent with low-grade appendiceal mucinous neoplasm presenting as intussusception-a case report and literature review.

BACKGROUND: Cases with intussusception caused by either intestinal hemangiomas or appendiceal mucinous neoplasms are extremely rare. CASE PRESENTATION: In this study, we reported a 47-year-old male presented with paroxysmal abdominal pain and postprandial bloating for 3 days. CT results indicated a high possibility of secondary intussusception in ascending colon. Histopathology indicated a mixed type of cavernous and capillary hemangioma, combined with low-grade appendiceal mucinous neoplasms (LAMNs) and intestinal obstruction. The patient underwent laparotomy and right hemicolectomy. Finally, the patient was followed up for 4 months with no disease progression. CONCLUSIONS: Rare studies reported the intestine hemangiomas coincided with appendix low-grade mucinous tumor. Its manifestations are not specific, which is a challenge in the preoperative diagnosis. For cases with intussusception that was not observed in time, it may lead to intestinal necrosis and diffuse peritonitis. Additionally, the ruptured mucinous tumor in the appendix may lead to pathogenesis of pseudomyxoma peritonei. Therefore, accurate diagnosis and appropriate surgery-based treatment contribute to the improvement of prognosis and severe outcomes among these patients.

Spectrum of MRI Features of Mucin-producing Neoplasms in the Abdomen and Pelvis.

Mucin-producing neoplasms in the abdomen and pelvis are a distinct entity, separate from simple fluid-containing neoplasms and loculated fluid collections. Mucin is a thick gelatinous substance and-owing to its high water content-has imaging features that can be mistaken for those of simple fluid-containing neoplasms with multiple imaging modalities. However, mucin-producing neoplasms arise from specific organs in the abdomen and pelvis, with unique imaging appearances, knowledge of which is important to guide accurate diagnosis and management. With its large field of view and high soft-tissue resolution, MRI has advantages over other imaging modalities in characterizing these neoplasms. The authors focus on the spectrum of MRI features of such mucin-producing neoplasms and illustrate how-despite a varied organ origin-some of these neoplasms share similar MRI and histopathologic features, thereby helping narrow the differential diagnosis. One common finding in these tumors is that the presence of internal complexity and solid enhancing components increases as the degree of malignant transformation increases. Lack of internal complexity generally indicates benignity. These tumors have a varied range of prognosis; for example, a low-grade appendiceal mucinous neoplasm is indicative of a good prognosis, while a mucinous tumor of the rectum is known to manifest at an early age with aggressive behavior and poorer prognosis compared with its nonmucinous counterpart. Online supplemental material is available for this article. ©RSNA, 2022.

Appendiceal tumours - A correlation of CT features and histopathological diagnosis.

Appendiceal tumours are uncommon neoplasms of the gastrointestinal tract. An understanding of the imaging appearances facilitates an accurate radiological description, which guides surgical and oncological management. In this study, a retrospective review of the CT imaging and histopathology of all cases of appendiceal tumours discussed at the oncology multidisciplinary meetings in a single centre, over an 8-year period (2012-2019) is performed. The array and incidence of both common and rare pathologies are investigated, and important characteristic imaging findings for radiologists to recognize are highlighted.

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

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