The coexistence of low-grade mucinous neoplasms of the appendix and appendiceal diverticula: a possible role in the pathogenesis of pseudomyxoma peritonei

Appendicular diverticulosis complicated by acute appendicitis and organizing abscess: what does the surgeon need to consider intraoperatively?

Acute appendicitis is a common surgical emergency, affecting 7%-10% of people worldwide, whereas appendicular diverticulosis is rare, occurring in 0.004%-2.1% of appendectomy cases and often mimicking appendicitis symptoms. A 35-year-old male presented with right lower quadrant pain, nausea, vomiting, and diarrhea. Clinical examination showed tenderness in the right iliac fossa. Imaging suggested uncomplicated acute appendicitis, but surgery revealed an appendiceal mass suspected to be a carcinoid tumor. Histopathology post-appendectomy diagnosed appendicular diverticulosis complicated by acute appendicitis. This case emphasizes the need for thorough histopathological examination in appendectomy cases to accurately diagnose and differentiate appendicular conditions. Appendiceal diverticulitis should be considered in the differential diagnosis of right lower quadrant pain to ensure proper surgical intervention and prevent complications.

Exploring the mysterious mucinous appendiceal neoplasm

Mucinous neoplasms of the appendix comprise a group of diagnostically challenging lesions that have generated significant controversy and confusion throughout the years, given their potential for aggressive behavior despite very bland cytologic features. Numerous classification schemes have been proposed to characterize and stage these lesions, but confusion remains among pathologists, surgeons, and oncologists regarding diagnostic criteria, therapeutic implications, and overall prognosis. This review summaries the current recommended nomenclature, histologic characteristics of each entity, and helpful features to distinguish neoplasia from benign mimics.

Extra-appendiceal mucinous neoplasms: A tumour with clinicopathologic similarities to low- and high-grade appendiceal counterpart

AIMS

Appendiceal mucinous neoplasms feature neoplastic mucinous epithelium with pushing borders and densely fibrotic walls. We have identified five examples of analogous colorectal tumours.

METHODS AND RESULTS

Slides, pathology reports, and clinical data were reviewed. Whole genome sequencing was performed in two cases. Three were women and the mean age was 70. Associated GI conditions included Crohn's disease [1], diverticulosis [2], and sarcoma of the terminal ileum [1]. Signs/symptoms included obstruction [2], nausea, vomiting, abdominal pain [1], and positive faecal immunohistochemical test [1]. Colonoscopic findings included narrowing [1], "fullness" [1], and caecal lesion concerning for GIST [1]. Tumours involved the rectosigmoid [2], sigmoid [1], transverse colon [1], and cecum [1] and ranged from 1.5 cm to 8.5 cm. All but one tumour arose in the setting of faecal stream abnormalities related to obstruction, diverticulosis, or bowel diversion. All cases showed columnar, variably mucinous epithelium associated with little-to-no lamina propria. All but one case showed fibrosis of the submucosa. Three cases had high-grade areas. Neoplastic glands and/or mucin dissected through the muscularis propria or subserosa in 3 examples. No extracolonic neoplastic cells/mucin, infiltrative invasion, or desmoplastic response were identified. Three patients with available follow-up [5.5-28 months] are alive. Whole genome sequencing identified pathogenic TP53 and ERBB2 variants, as well as ERBB2 copy number amplification in one high-grade example.

CONCLUSIONS

Though these tumours share clinicopathologic characteristics with their appendiceal counterparts, our cohort is too small to draw solid conclusions. We propose the term "extra-appendiceal mucinous neoplasm [EAMN]" for these rare lesions.

Clinical features and risk factors for appendiceal diverticulitis: a comparative study with acute appendicitis

PURPOSE

Despite their similar clinical characteristics, appendiceal diverticulitis (AD) and acute appendicitis (AA) are pathologically distinct. This study compared the clinical features of AD and AA and identified relevant risk factors.

METHODS

Patients who underwent appendectomy with a preoperative diagnosis of either AD or AA were categorized based on histopathological findings. The two groups were compared in terms of various clinical factors.

RESULTS

Among the 854 patients included in the study, a histopathological evaluation revealed 49 and 805 cases of AD and AA, respectively. A univariate analysis demonstrated that AD was more prevalent than AA among older, taller, and heavier males. A multivariate analysis revealed that male sex, a white blood cell (WBC) count < 13.5 × 103/μL, an eosinophil count ≥ 0.4%, and a mean corpuscular volume (MCV) ≥ 91.6 fL were significant factors differentiating AD from AA. In addition, pathological AD emerged as an independent risk factor for abscess and/or perforation.

CONCLUSIONS

AD was associated with an older age, robust physique, and significant risk of abscess and/or perforation despite a low WBC count. In addition to imaging modalities, the preoperative factors of male sex, a WBC count < 13.5 × 103/μL, an eosinophil count ≥ 0.4%, and a MCV ≥ 91.6 fL may be useful for distinguishing AD from AA.

A case report on appendicular diverticulitis: Eluding traditional diagnosis

INTRODUCTION AND IMPORTANCE

Diverticula of the vermiform appendix are rare entities. Although the pathogenesis and natural course of appendiceal diverticulitis (AD) are different from acute appendicitis, AD is treated like acute appendicitis because of similar clinical manifestations and low incidence.

CASE PRESENTATION

We describe cases of two male patients of different ages who respectively underwent elective laparoscopic appendectomy and an emergent laparoscopic appendectomy in a multi-speciality hospital in Kerala, India. Both of them had acute appendicitis, as confirmed by imaging and laboratory testing. Subsequent histopathological examination revealed AD.

CLINICAL DISCUSSION

AD is an uncommon but potentially more serious form of appendiceal disease that can mimic acute appendicitis or malignancy. The first patient mimicked a malignancy with the mass presentation, while the second case presented like appendicitis. Unlike colonic diverticula, AD diverticula are typically not detectable by imaging or colonoscopy, which poses a diagnostic challenge.

CONCLUSION

In patients who present with lower abdominal pain or who may have appendicitis, AD should be considered as a differential diagnosis.

Surgical rarities: case report of appendicular diverticulitis and literature review

Appendicular diverticulosis is a rare condition observed in about 0.004–2% of all appendectomy specimens. Risk of perforation/bleeding is high and a relevant association with mucinous neoplasms is known. Appendectomy is indicated even in case of occasional finding. We present the case of a 22-year-old man who entered the Emergency Room for pain in right iliac fossa. Blood tests showed only a slight increase in C-reactive protein. Abdominal ultrasound (US) evidenced an appendix with thickened walls and a rounded fluid-filled hypoechoic lesion at its distal tip. Laparoscopic appendectomy confirmed the presence of mucocele. Postoperative course was uneventful and the patients discharged on postoperative day 3. Histological examination indicated diverticulitis/peridiverticulitis of the appendix and acute suppurative appendicitis. No perforation of the diverticula was detected. No neoplastic epithelium/mucous material was observed. In our case, preoperative US proved to be a useful alternative to computed tomography for the diagnosis.

A Case of a Rare, Incidental Discovery of Fibrous Obliteration of an Appendiceal Diverticulum

Diverticulosis of the appendix (DA) is rare and frequently found incidentally. Some cases are discovered after presenting with similar symptomatology to acute appendicitis, whereas other cases may be completely silent. Fibrous obliteration (FO) is a histologic finding indicative of cellular proliferation secondary to relapses of subclinical inflammatory processes. We report a case of a 75-year-old female with a history of chronic, intermittent abdominal pains who presented to the general surgery clinic after an abnormal thickening of the appendix was discovered on abdominal and pelvic computed tomography imaging. The patient underwent laparoscopic appendectomy for suspicion of malignancy. The histologic evaluation of the specimen demonstrated a diverticulum at the distal end of the appendix with FO of the lumen. We suspect the chronic nature of her disease course may have led to the FO of the diverticulum. An extensive literature search was performed, which revealed no other cases of FO of appendiceal diverticula. This may be the first case of diverticulosis of the appendix with FO in the English medical literature. If DA is discovered early with non-invasive imaging, surgical excision should be performed prophylactically as an association with an increased risk of perforation and neoplastic progression has been found.

Appendiceal diverticulum masquerading as acute appendicitis

Appendiceal diverticula present as rare clinical finding and are most confused with acute appendicitis. A 65-year-old female was presented to our surgical service after 1 day of right lower quadrant abdominal pain and a computed tomography evaluation, read as a diagnosis of acute appendicitis. Due to the location and quality of pain and intraoperative findings acute appendicitis was our preliminary diagnosis. Follow up with histopathology confirmed acute inflammation of an appendiceal diverticulum. With discordance in original diagnosis from final pathological evaluation, we suggest appendiceal diverticula as an important differential to consider in patients of similar clinical presentation. Surgical treatment with appendectomy and final histological diagnosis are essential in the proper treatment of this rare clinical finding.

A case of diverticulum of the appendiceal base resembling a submucosal tumor of the cecum under colonoscopy: a hitherto undescribed lesion

BACKGROUND

Diverticulosis of the appendix is an uncommon clinical entity, and a preoperative diagnosis is often difficult. Herein we report an unusual case of appendiceal diverticulosis.

CASE PRESENTATION

A 72-year-old male was referred to our hospital to examine the cause of hematochezia. A colonoscopy study showed a protruding lesion resembling a submucosal tumor (SMT), approximately 20 mm in diameter, at the site around the appendiceal orifice of the cecum. An abdominal computed tomography and magnetic resonance imaging showed a cystic lesion at the appendiceal base. The lesion was clinically diagnosed as a cystic tumor of the appendix, but the possibility of a malignant tumor could not be excluded. Therefore, a laparoscopic ileocecal resection with lymph node dissection was performed. The pathological examination of the resected specimen revealed that the lesion was a diverticulum (pseudodiverticulum) occurring solitarily at the appendiceal base, in which the mucosal layer of the appendix was invaginated into the submucosa of the adjacent cecum, thus forming an SMT-like lesion.

CONCLUSION

To our knowledge, this is the first case report in the English literature showing that an appendiceal diverticulum can manifest as an SMT-like lesion in the cecum. This condition should be recognized as a differential diagnosis for such lesions.

A case of Pseudomyxoma Peritonei of an unexpected origin

Background

Pseudomyxoma peritonei (PMP) is a complex and partially understood disease defined by mucin deposits in the peritoneal cavity, mostly of appendiceal origin caused by the rupture of a mucocele often containing Low or High grade Appendiceal Mucinous Neoplasm (LAMN/HAMN). Other origins include primitive ovarian mucinous cystadenoma or cystadenocarcinoma almost always with an associated teratoma, but to our knowledge no case of ovarian teratomatous appendiceal-like mucocele with LAMN has been reported as a cause of PMP.

Case presentation

A 25-year old female with infertility was diagnosed with an isolated left ovarian tumor in a context of PMP. Histological examination revealed an ovarian teratoma containing an appendiceal-like structure with mucocele and LAMN, without any associated lesion of the appendix on full histological analysis. Molecular characterization of the ovarian lesion showed co-KRAS and GNAS mutations, as described in PMP of appendiceal origin, while only KRAS mutations are reported in primitive ovarian mucinous tumor.

Conclusions

Detection of co-KRAS and GNAS mutations in our case of ovarian teratomatous appendiceal-like mucocele with LAMN shows that when PMP derives from a mucinous ovarian lesion (with histological proof of none-appendiceal involvement), it is probably of a digestive teratomatous origin, emphasizing the need to actively search for tetatomatous signs in a context of ovarian PMP.

Controversies in appendiceal pathology: Mucinous and goblet cell neoplasms

Appendiceal goblet cell adenocarcinomas and mucinous neoplasms are uncommon compared with other epithelial tumours of the gastrointestinal tract. Both tumour types have been subjected to terminology that belies their biological risk and leads to confusion. Goblet cell adenocarcinomas display patchy staining for endocrine markers and, thus, were previously classified as goblet cell carcinoids. Unlike well-differentiated endocrine neoplasms, however, they often contain high-grade glandular elements and pursue an aggressive course akin to that of conventional adenocarcinoma. Although several authors have recently proposed grading schemes to predict behaviour among goblet cell neoplasms, most that contain high-grade components have already spread beyond the appendix at the time of diagnosis, whereas those confined to the appendix almost always have low-grade features; the added value of grading these tumours is limited. Contradictions also surround the nomenclature of mucinous neoplasms. The World Health Organization and others promote non-malignant terminology to describe metastatic mucinous neoplasms of the peritoneum and eliminate a benign category entirely, even though virtually all neoplasms confined to the appendix pose no recurrence risk following appendectomy. 'Low-grade appendiceal mucinous neoplasm' now encompasses a spectrum of benign tumours and malignant neoplasms in the appendix and peritoneum. Although using an umbrella term in this fashion simplifies the roles of pathologists, it provides essentially no actionable information beyond that which is already clinically apparent. Broad strokes nomenclature also ensures that many patients with no risk of recurrence will receive unnecessary surveillance while others will undergo inappropriate surgical procedures due to lapses in communication. Moreover, a surprising number of non-neoplastic mucinous lesions are misclassified as low-grade appendiceal mucinous neoplasms, which can result in unwarranted patient concern or even mismanagement. The purpose of this review is to critically evaluate the literature and describe an approach to appendiceal neoplasms that more clearly denotes their biologic risk.

Coexistence of low-grade mucinous neoplasm and carcinoid (collision tumor) within multiple appendiceal diverticula: A case report

Neoplasms of the appendix are very rare. They usually show glandular or neuroendocrine differentiation, and when they both occur in the same area, it is called a “collision tumor.” Low-grade mucinous neoplasms associated with appendiceal diverticula are also uncommon. The appendectomy specimen of a 60-year-old man contained dense and mucoid luminal content on the distal tip, and similarly a solid, yellow, lumen-obscuring tumor with a diameter of 1.5 cm at the base of the appendix was detected. Microscopically, there were three diverticula that comprised herniation of the mucosal layer through the appendiceal wall. Interestingly, all of the diverticula and the normal-appearing appendiceal wall were lined by adenomatous epithelium. The luminal portion had pools of mucin-containing, rare clusters of low-grade epithelium that gave rise to the diagnosis of a “low-grade mucinous neoplasm.” The solid-appearing tumor was diagnosed as a “neuroendocrine neoplasm,” and there was no transition zone between these two types of tumors. There are some cases that have been reported as low-grade mucinous neoplasms associated with appendicular diverticula and collision tumors consisting both mucinous neoplasms and carcinoid tumors in the literature; our case has a unique appearance with two different types of tumors both in the appendix wall and within multiple diverticula.

Standardization of the pathologic diagnosis of appendiceal mucinous neoplasms

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.

Diverticular Disease of the Appendix Is Associated with Complicated Appendicitis

INTRODUCTION

Diverticular disease of the vermiform appendix (DDA) has an incidence of 0.004 to 2.1% in appendicectomy specimens. DDA is variably associated with perforation and malignancy. We report a single-center experience of DDA. The primary aim is to validate the association of DDA with complicated appendicitis or malignancy, and the secondary aim is to validate systemic inflammatory response syndrome (SIRS) criteria and quick Sepsis-related Organ Failure Assessment (qSOFA) scores.

METHODS

The histopathology reports of 2,305 appendicectomy specimens from January 2011 to December 2015 were reviewed. Acute appendicitis was found in 2,164 (93.9%) specimens. Histology of the remaining 141 (6.1%) patients revealed: normal appendix (n = 110), DDA (n = 22), endometriosis of appendix (n = 6), and an absent appendix (n = 3). Patient demographics, clinical profile, operative data, and perioperative outcomes of DDA patients are studied. Modified Alvarado score, Andersson score, SIRS criteria, and qSOFA scores were retrospectively calculated.

RESULTS

The incidence of DDA was 0.95%. Ten patients (45.5%) had diverticulitis. The mean age of DDA patients was 39.5 years (range 23-87), with male preponderance (n = 12, 54.5%). The median Modified Alvarado score was 8 (range 4-9), and the median Andersson score was 5 (range 2-8). Fourteen patients (63.6%) had SIRS, and none had a high qSOFA score. Eight patients (36.4%) had complicated appendicitis (perforation [n = 2] or abscess [n = 6]). Eleven (50%) patients underwent laparoscopic appendicectomy. There were three 30-day readmissions and no mortality.

CONCLUSION

DDA is a distinct clinical pathology associated with complicated appendicitis.

Congenital Appendiceal Diverticulum: An Incidental Finding During an Appendectomy

Diverticula are small outpouchings that form at weak points in the wall of the digestive tract. They are commonly found in the colon, and while they can occur anywhere in the digestive tract, occurrence in the appendix is rare. Here, we report the case of a young woman presenting with complaints of right lower quadrant abdominal pain. The patient’s physical examination, laboratory values, and computed tomography (CT) result supported the presumptive diagnosis of uncomplicated appendicitis. The patient underwent a laparoscopic appendectomy, where an appendiceal diverticulum was appreciated. A postoperative pathology report supported the diagnosis of a true appendiceal diverticulum. The patient’s symptoms improved postoperatively, and her recovery has been unremarkable. We conclude that appendiceal diverticula are often incidental findings that should be removed along with the appendix to reduce the risk of malignancy and perforation.

The Frontiers of Appendiceal Controversies: Mucinous Neoplasms and Pseudomyxoma Peritonei

Appendiceal mucinous neoplasms show a range of morphologic features and biological risk. At one end of the spectrum, high-grade adenocarcinomas are cytologically malignant with infiltrative invasion, lymph node metastases, and behavior similar to that of extra-appendiceal mucinous adenocarcinomas. At the other end, mucinous neoplasms confined to the mucosa are uniformly benign. Some cases lying between these extremes have potential risk to metastasize within the abdomen despite a lack of malignant histologic features. They show "diverticulum-like," pushing invasion of mostly low-grade epithelium through the appendix with, or without, concomitant organizing intra-abdominal mucin. The latter condition, widely termed "pseudomyxoma peritonei," tends to pursue a relentless course punctuated by multiple recurrences despite cytoreductive therapy, culminating in death for many patients. The combination of bland histologic features and protracted behavior of peritoneal disease has led some authors to question whether these metastatic tumors even represent malignancies. The World Health Organization and its cadre of experts widely promote usage of "low-grade appendiceal mucinous neoplasm" as an umbrella term to encompass benign and malignant conditions, as well as those that have uncertain biological potential. Although this practice greatly simplifies tumor classification, it causes confusion and consternation among pathologists, clinical colleagues, and patients. It also increases the likelihood that at least some patients will undergo unnecessary surveillance for, and treatment of, benign neoplasms and non-neoplastic conditions. The purpose of this review is to critically evaluate the relevant literature and discuss a practical approach to classifying appendiceal mucinous neoplasms that more closely approximates their biological risk.

Updated staging and patient outcomes in low-grade appendiceal mucinous neoplasms

Low-grade appendiceal mucinous neoplasms (LAMNs) exhibit drastically different clinical course and prognosis depending on tumor stage, particularly as it relates to the extent and cellularity of peritoneal involvement. In this context, recent changes in staging guidelines have sought to clarify criteria for pT and pM categories. This study's aim was to identify clinicopathological features associated with patient outcomes, especially as they pertain to updated stage groups. We reviewed LAMNs from 192 patients (mean age: 56.9 years, 119 (62.0%) women). The tumors consisted of 66 (34.4%) pTisM0, 16 (8.3%) pT3M0, 16 (8.3%) pT4aM0, 27 (14.1%) pTxM1a, and 67 (34.9%) pTxM1b cases. In multivariate analysis, only gross perforation was significantly associated with higher TNM group stage (p = 0.001; OR 3.3, 95% CI: 1.7-6.4). Of 165 (85.9%) patients with clinical follow-up, 51 (30.9%) had disease progression (over a mean 33.7 months, range: 4.7-121.7), whereas over significantly longer follow-up (mean 48.7 months, range: 3.1-143.9; p = 0.004), 114 (69.1%) patients did not. In multivariate analysis, higher TNM stage was significantly associated with disease progression (p = 0.029; OR 18.3, 95% CI: 1.4-246.0). In Kaplan-Meier analysis, none of 74 patients with disease limited to the appendix (pM0), 6 of 27 (22.2%) cases with peritoneal involvement by acellular mucin only (pM1a), and 45 of 64 (70.3%) tumors with intraperitoneal deposits containing neoplastic cells (pM1b) showed disease progression (p < 0.001). These differences in progression-free survival among TNM groups persisted when limiting the analysis to patients who had undergone successful cytoreductive surgery (p = 0.050). Finally, in four patients (all with pM1b disease) death was attributed to disease progression whereas there was no disease-specific mortality in the pM0 and pM1a groups (p = 0.020). These data support the designation of LAMNs with acellular peritoneal mucin as having an intermediate prognosis between cases limited to the appendix and those with intraperitoneal deposits containing neoplastic epithelium.

A case of Type 2 appendiceal diverticulum perforated and a review of the literature

BACKGROUND

Appendiceal diverticulosis disease is a rare entity. An perforated appendiceal diverticulosis mimicking acute appendicitis is a extremely unusual surgical finding and the reported prevalence is between 0.014 and 3.7%.

CASE REPORT

We report the case of an elderly man, who presented with a typical clinical image of acute appendicitis and underwent laparoscopic surgery. Intraoperative an acute appendicitis with localized peritonitis was identified and a laparoscopic appendectomy was performed, but pathologic analysis demonstrated a type 2 appendiceal diverticulitis.

CONCLUSION

Appendiceal diverticulosis disease should be included in differential diagnosis of patients presenting with clinical signs of an acute appendicitis and prompt surgical treatment is essential in order to avoid severe complications.

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.

Imaging in Appendicular Diverticulosis with Appendicitis

Appendicular diverticulosis (AD) is an extremely rare condition. They are either incidentally detected in a normal or inflamed appendix or as diverticulitis manifesting clinically as appendicitis. It is commonly a radiological or pathological diagnosis. On computed tomography (CT), AD can mimic focal perforation. There are reported associations between AD and appendicular adenocarcinoma. This case reports the classical features of AD on CT with background appendicitis.

Updates in Appendix Pathology: The Precarious Cutting Edge

Mucinous appendiceal tumors include low-grade appendiceal mucinous neoplasm, high-grade appendiceal mucinous neoplasm, and mucinous adenocarcinoma. Nonmucinous adenocarcinomas are less frequent. Recent consensus guidelines and the latest edition of the World Health Organization classification will allow consistent use of agreed nomenclature. Accurate diagnosis is important not only for patient management but also to allow comparison of results between centers and tumor registries. Serrated polyps are the most common benign polyp in the appendix. They need to be distinguished from low-grade appendiceal mucinous neoplasm, which can also mimic other benign conditions. Goblet cell adenocarcinomas are a distinctive type of appendiceal neoplasm.

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.

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.

Systematic review and meta-analysis of the association between diverticulosis of the appendix and neoplasia

BACKGROUND

Diverticula of the appendix (DA) are infrequent and their clinical implications are often overlooked. Several studies have found a significantly increased prevalence of neoplasms in appendiceal specimens with diverticula. Despite the potential clinical implications, there is a paucity of literature. A systematic review and meta-analysis was performed to evaluate the prevalence of DA and its association with neoplasia.

METHODS

A systematic search of literature (Cochrane, EMBASE, PubMed and Medline) reporting the prevalence of DA and association with neoplasia was performed in November 2019. Relevant articles were assessed in accordance with the PRISMA guidelines. Risk of bias assessment was carried out using modified Newcastle-Ottawa scale. Meta-analysis with risk ratio and random-effects model was performed using RevMan.

RESULTS

The initial search identified 1122 potential articles of which 11 were appropriate for quantitative analysis. The prevalence rate of DA was 1.74%. The mean age of patients with DA and those without DA was 41.2 and 33.9 years, respectively. The ratio of male to female was 1.8:1. The prevalence of neoplasia in specimens without DA versus those with DA was 1.28% and 26.94%, respectively. Only four studies addressed the prevalence of locoregional neoplasia in the setting of DA compared to control. Meta-analysis with random-effects model demonstrated that pooled risk ratio was 25.46 (95% confidence interval 12.77-50.75, P < 0.00001).

CONCLUSION

The strong association with neoplasia in this meta-analysis reinforces the clinical significance of DA. Surgeons, pathologists and radiologists should be mindful of this uncommon pathology and consider individualized patient management, until further evidence can direct clinical guidelines for the management of patients with DA.

Clinical characteristics of appendiceal diverticular disease

BACKGROUND

Appendiceal diverticular disease (ADD) is a rare pathology which is associated with an increased mortality risk due to rapid perforation and high rates of neoplasm. In our study, we aimed to evaluate the clinical and histopathological characteristics of ADD with differences from acute appendicitis (AA) diagnosis and to determine the association with neoformative processes.

METHODS

The 4279 patients who underwent appendectomy were evaluated retrospectively. ADD patients histopathologically classified into four groups. Patients' demographic characteristics, imaging and preoperative laboratory findings, additionally postoperative histopathology results were compared between groups.

RESULTS

The prevalence of ADD was 2.29% (n = 98). In addition, the male/female ratio was 2.37 in ADD patients who were found to be significantly older than those with AA patients. Type III was the most frequently (62.2%) identified sub-group of ADD. The incidence of neoplasms, plastrone, and Littre's hernia was found statistically higher in ADD group than AA group. Mucinous adenomas (10.2%) was the most common neoplasm while the carcinoid tumor (1%) and precancerous serrated adenomas (4.1%) were also reported.

CONCLUSIONS

As a result, high neoplasm in ADD patients can be shown with incidence of perforation and plastron, and in order to avoid possible neoplasm or major complications, it is necessary to carry out new studies for the right diagnosis of ADD whether the diagnosis is done preoperatively or ıntraoperatively. We recommend surgical resection of the ADD, which may even be incidentally detected during any surgical procedure, due to its high risk of neoplasm and rapid perforation.

Clinical significance of appendiceal diverticulum: a significant marker for appendiceal neoplasia in Australian patients

INTRODUCTION

Diverticula of the appendix (DA) have a reported incidence of up to 2.1%. They are primarily detected incidentally, through imaging and intraoperative or histologic diagnosis. This study's objective was to examine the prevalence of DA, and its relationship with inflammation and neoplasia, as well as review the literature with respect to clinical outcomes and ability to identify DA preoperatively.

METHODOLOGY

A retrospective search of all patients undergoing an appendicectomy for right lower quadrant pain at a single institution between 2004 and 2017 was conducted. Histopathology reports for evidence of DA, location of the DA, presence of inflammation, and any relationship between DA and neoplasms (adenoma, carcinoma, carcinoid, lymphoma, and mucinous neoplasm) within the appendix were reviewed. Clinical notes, operative records, and preoperative imaging were also reviewed.

RESULTS

Two thousand seven hundred eleven patient were included in the study, with a mean age of 34 years, with acute appendicitis found in 82.5%. 31.6% of patients with DA had associated inflammation of the DA. DA was present in 57 patients (2.1%), with 55 patients in the total cohort having neoplasia (2.0%). Patients with DAs were ten times more likely to have appendicular neoplasm than patients without a DA (17.5 vs 1.8%; p < 0.0001, OR 11.8 95%, CI 5.6-24.8).

CONCLUSION

This is the first Australian study demonstrating DAs are a significant marker of appendiceal neoplasm. Appendicectomy in all incidentally discovered diverticulum should be considered. Due to a paucity of data, research is required into this area to assess for the need for endoscopy following diagnosis.

Appendiceal diverticulosis: a harbinger of underlying primary appendiceal adenocarcinoma?

Diagnosis of primary appendiceal adenocarcinoma (PAA) is hindered by its rarity and largely asymptomatic nature. Appendiceal diverticulosis (AD) is equally rare. We report an unusual case of PAA presenting with perforated appendiceal diverticulitis, and discuss a review of the literature about its association, and its surgical and pathological implications. A middle-aged man was admitted with right iliac fossa (RIF) pain and a corresponding tender abdominal mass for 5 days. Computerised tomography (CT) scan demonstrated a thickened appendix with 3 cm abscess at its base. During laparoscopic appendicectomy, the appendiceal phlegmon was adhered to the surrounding bowel. Histology showed a perforated diverticulum near the appendiceal tip, and a primary appendiceal well-differentiated adenocarcinoma located proximal to it with clear margins. Up to 48% of ADs are associated with appendiceal neoplasms, but its coexistence with PAA is reported in fewer than ten instances worldwide. Obstructing appendiceal tumours, by raising intraluminal pressure, can predispose to AD formation. Intestinal-type PAA is often managed like its colorectal counterpart, although controversies about management of PAA in a perforated AD remain. Recognition of the association of AD and PAA is critical to ensure meticulous oncological resection and histological examination.

An Update on the Diagnosis, Grading, and Staging of Appendiceal Mucinous Neoplasms

Despite advances in our understanding of appendiceal mucinous neoplasms and their relationship to the pseudomyxoma peritonei syndrome, the classification of mucinous tumors of the appendix is still confusing. This review will provide an update on the various classification systems that have been recently proposed for appendiceal mucinous neoplasia, with a particular emphasis on how to handle and report the histologic findings for these tumors using the newly published Peritoneal Surface Oncology Group International (PSOGI) and American Joint Committee on Cancer (AJCC) eighth edition guidelines. A simplified approach to diagnostic reporting of appendiceal mucinous neoplasms based on the 3-tier AJCC grading scheme is detailed and specific criteria for assessing grade in appendiceal mucinous neoplasia will be outlined. In addition, histologic mimics of appendiceal mucinous neoplasia and how to distinguish these mimics from mucinous neoplasia will be discussed. Finally, despite improvements in diagnostic terminology, significant challenges in classifying appendiceal mucinous neoplasia persist and diagnostic strategies will be detailed to assist practicing pathologists in these challenging scenarios.

Low-grade appendiceal mucinous neoplasm and endometriosis of the appendix

Background

A distended, mucous-filled appendix is known as an appendiceal mucocele. They are a rare form of an appendiceal mass and develop from both benign and malignant processes. Mucoceles can develop secondarily to an obstruction, such as from a fecalith, scarring or, rarely, endometriosis. Only 12 cases of non-neoplastic appendiceal mucoceles caused by endometriosis have been previously described. The association between neoplastic appendiceal mucoceles in the presence of endometriosis is described for the first time in this report.

Case presentation

A 57-year-old woman presented with a chief complaint of worsening abdominal pain over the past 3 months. Imaging studies revealed an appendiceal mass. Laparoscopic evaluation confirmed an appendiceal mucocele, and the patient underwent complete appendectomy. No evidence of mucinous or endometrial deposits were present within the abdominal cavity. Pathological diagnosis revealed low-grade appendiceal mucinous neoplasm (LAMN) with evidence of endometriosis within the muscularis propria of the appendix. The patient recovered without complications and her abdominal pain completely resolved.

Conclusions

Endometriosis of the appendix is a rare manifestation and is most often identified as an incidental finding. Endometriosis leading to an obstructive mucocele of the appendix is an exceedingly rare finding, having only been described 12 times in the medical literature. LAMN in the presence of endometriosis of the appendix is described for the first time in this report. The association between appendiceal neoplasms in the presence of endometriosis requires further research in order to optimize operative treatment.

Unexpected histopathology of acute appendicitis

INTRODUCTION

Appendicular diverticula and associated diverticulitis is a rare disease. Patients present commonly with symptoms of acute appendicitis and require laparoscopic or open surgery. Diagnosis is usually made only on histology. Here, we present a rare case of acute diverticulitis of the appendix.

CASE PRESENTATION

A 33-year old gentleman presented with right iliac fossa pain of 3 days duration. On admission, appendicitis was diagnosed on Computerized Tomography (CT) scan and laparoscopic appendicectomy was subsequently performed. Intra-operative findings were unremarkable and recovery was uneventful. Histopathology however revealed diverticulitis of appendix with acellular mucin.

DISCUSSION

Acute diverticulitis of the appendix is an exceptionally rare condition and reported in 0.004%-2% of appendicectomies. It presents usually when complicated with perforation and bleeding. There is however a strong association with certain malignancies such as mucinous neoplasm, carcinoid and Pseudomyxoma peritoneii. Radiological proven appendicular diverticulum requires early intervention due to higher chance of diverticulitis related complication. Surgeons should be aware about this rare disease and may consider elective surgery in view of potential risk of complications and malignancy.

CONCLUSION

We concluded that because of strong malignant association, it would be recommended that all appendix specimens should inspect during and after surgery and concurrent examination of peritoneal cavity is recommended.

Retrospective study of 24 cases of acute appendiceal diverticulitis: CT findings and pathological correlations

PURPOSE

Appendiceal diverticulitis is relatively rare and is difficult to distinguish clinically and radiologically from acute appendicitis. The aim of this study was to describe the computed tomography (CT) findings of acute appendiceal diverticulitis.

MATERIALS AND METHODS

Among the 1329 patients who underwent appendectomy at our institution between January 2010 and July 2015, 28 were diagnosed pathologically with appendiceal diverticulitis, including 24 patients who were evaluated by preoperative CT. The control group consisted of 38 patients without diverticulitis. Average age of patients, ratio of males to females, appendiceal diameter, presence of a diverticulum, diverticular enhancement, peri-appendiceal fat stranding, peri-appendiceal loculated fluid and perforation, and the presence of appendicolith were evaluated retrospectively.

RESULTS

Peri-appendiceal fat stranding (p < 0.005), appendiceal diameter (p < 0.005), and peri-appendiceal loculated fluid differed significantly between the diverticulitis and non-diverticulitis groups (p < 0.005).

CONCLUSION

Although relatively uncommon, appendiceal diverticulitis should be included in the differential diagnosis of acute appendicitis. It differs from typical acute appendicitis by the presence of an inflamed diverticulum, seen on CT. These patients are also more likely to have peri-appendiceal extra-luminal loculated fluid, peri-appendiceal fat stranding, and a larger diameter of the appendix. The latter finding is likely due to the increased intraluminal pressure.

Appendiceal diverticulitis, a rare relevant pathology: Presentation of a case report and review of the literature

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Appendiceal diverticulitis is often overlooked with high risk of perforation.

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Appendiceal diverticula is often associated to appendiceal neoplasm.

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Accurate appendectomy should be performed in order to permit appropriate pathological examination.

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Prophylactic appendectomy should be performed in asymptomatic patients with appendiceal.

Introduction

Appendiceal diverticulitis is a rare pathology that mimics acute appendicitis. Appendiceal diverticula are classified into congenital and acquired with difference in incidence and pathogenesis. Appendiceal diverticulitis is often overlooked because of mildness of symptomatology with increasing risk of complications, such as perforation. Appendiceal diverticula are often associated to higher risk of neoplasm especially carcinoid tumors and mucinous adenomas.

Presentation of case

A 40-year-old caucasic male presented into Emergency Room with right lower quadrant pain associated with vomit, abdominal tenderness, fever and moderate leukocytosis (11.93 × 10; neutrophils 78.5%). Acute appendicitis was suspected and a surgical approach was chosen with a McBurney access. The removed specimen (Figs. 1 and 2) was 11 cm long with multiple hyperaemic and oedematous diverticular protrusions. The postoperative course was regular. Discharging was on 4th postoperative day in optimal clinical conditions. The histological examination (Fig. 3) showed acute inflammation of appendiceal pseudodiverticula with acute peridiverticulitis and abscess.

Discussion

Currently, appendiceal diverticulitis is often overlooked with high risk of complications, above all perforation. Attention should be kept during the surgical procedure and the patholological examination in order to identify any associated neoplasm.

Conclusion

Appendiceal diverticulitis should be considered in adult male patients with right lower quadrant pain or tenderness. Accurate appendectomy should be performed in order to permit an appropriate pathological examination and possible associate neoplasm should always be searched through. Prophylactic appendectomy should be performed in case of incidental finding of appendiceal diverticula in asymptomatic patients in order to avoid the high perforation risk.

Mucinous Balls Tangled With Mesothelial Cells and MUC2-Positive Cancer Cells in the Ascites of Pseudomyxoma Peritonei

Pseudomyxoma peritonei (PMP) is characterized by extensive mucinous ascites following rupture of mucinous neoplasms of an intra-abdominal origin, and contain secreted gel-forming mucins such as MUC2 and MUC5AC. We encountered a 66-year-old Japanese man complaining of abdominal distension. Ascites at the site was gelatinous upon gross examination, and needle aspirate smears showed histiocytes and many mucinous balls wrapped in spindle cells, which were positive for vimentin, pan-cytokeratin, and podoplanin. The cell block showed several adenocarcinoma clusters, which were positive for MUC2, MUC5AC, CK20, and CDX-2, and negative for CK7. From these findings, a diagnosis of PMP arising from colon cancer was indicated. Cytoreductive surgery was performed, and the cystic diverticulum was found to be infiltrated by tumor cells in the sigmoid colon that caused PMP. Mucinous balls surrounded by mesothelial cells and MUC2-positive adenocarcinoma cells are useful clues in the diagnosis of PMP. Diagn. Cytopathol. 2016;44:628-631. © 2016 Wiley Periodicals, Inc.

Low-grade mucinous neoplasia in a cecal diverticulum: A case report

INTRODUCTION

Low-grade mucinous neoplasia is an uncommon benign tumor that develops in the appendix. The development of mucocele disease has never been reported in a colonic diverticulum. We present a case developing low-grade mucinous neoplasia in a cecal diverticulum.

PRESENTATION OF CASE

A tumor in the ileocecal region was found during a medical examination of a 66-year-old woman. Three months later, the tumor was still present and the patient developed abdominal pain. Laparoscopic ileocecal resection with D2 lymph node dissection was performed. Histopathological examination revealed a low-grade mucinous neoplasm in a cecal diverticulum.

DISCUSSION

Colonic mucoceles reportedly originate from the appendix. There are no previous reports of mucocele disease in a colonic diverticulum worldwide. This report reviews and discusses the management of the appendiceal mucoceles.

CONCLUSION

The incidence of colonic diverticula has recently begun to increase in Japan. The possibility of a mucocele within a colonic diverticulum should be considered in patients with submucosal colonic tumors.

Diverticulitis of the appendix, a distinctive entity: preoperative diagnosis by computed tomography

Diverticular disease of the appendix is rare and is usually diagnosed during surgery. We report a case of a 50-year-old man who presented to the emergency department with right lower quadrant pain of 1-day duration. A preoperative diagnosis of appendiceal diverticulitis was made by computed tomography of the abdomen. The patient underwent emergency laparoscopic appendectomy, which confirmed the diagnosis.

Appendiceal diverticulitis clinically masquerading as an appendiceal carcinoma

Appendiceal diverticulosis is a rare condition. Herein reported is a case of appendiceal diverticulosis and diverticulitis clinically masquerading as appendiceal carcinoma. A 62-year-old woman presented with abdominal pain. US and CT showed a tumor measuring 5 × 4 × 4 cm in vermiform appendix. Colon endoscopy showed mucosal elevation and irregularity in the orifice of vermiform appendix. A biopsy of the appendiceal mucosa showed no significant changes. Clinical diagnosis was appendiceal carcinoma and wide excision of terminal ileum, appendix, cecum, and ascending colon was performed. Grossly, the appendix showed a tumor measuring 5 × 3 × 4 cm. The appendiceal lumen was opened, and the appendiceal mucosa was elevated and irregular. The periappendiceal tissue showed thickening. Microscopically, the lesion was multiple appendiceal diverticula. The diverticula were penetrating the muscle layer. The mucosa showed erosions in places. Much fibrosis, abscess formations, and lymphocytic infiltration were seen in the subserosa. Abscesses were also seen in the diverticular lumens. Some diverticula penetrated into the subserosa. The pathologic diagnosis was appendiceal diverticulitis. When they encounter an appendiceal mass, clinicians should consider appendiceal diverticulitis as a differential diagnosis.

Clinical implications of diverticular disease of the appendix. Experience over the past 10 years

BACKGROUND

Diverticular disease of the appendix is an uncommon condition, with an incidence from 0.004 to 2.1%. It usually occurs between the fourth or fifth decades of life, does not present gastrointestinal symptoms but only insidious abdominal pain. Patients usually delay consultation, leading to increased morbidity and mortality. The aim of this study was to determine the clinical features of diverticular disease of the appendix.

METHODS

A retrospective study of all patients undergoing appendectomy in a tertiary hospital between September 2003 and September 2013 was performed.

RESULTS

During this period, 7,044 appendectomies were performed, and 42 cases of diverticular disease of the appendix were found, which represents an incidence of 0.59%. A total of 27 patients were male. The mean age was 46.6±21 years. The average hospital stay was 4.5 days. A perforated appendix was identified in 46% of patients. In 80% of the cases, a complementary imaging test was performed. The incidence of neoplastic disease with diverticulum of the appendix was 7.1%.

CONCLUSIONS

Diverticular disease of the appendix is an incidental finding. In its acute phase, it presents as an acute appendicitis. The treatment of choice is appendectomy. It presents a higher risk of developing neoplastic disease of the appendix.

[Peritoneal pseudomyxoma: an overview emphasizing pathological assessment and therapeutic strategies]

Pseudomyxoma peritonei is a clinical entity characterized by a gelatinous ascite associated with mucinous tumor deposits spreading on peritoneal surface and potentially invading abdominal organs. It is considered as a tumor process linked, in most of cases, to a mucinous appendiceal neoplasm. Pseudomyxoma peritonei may benefit from a therapeutic strategy combining cytoreductive surgery and intra-peritoneal chemotherapy, which has led to a major prognosis improvement. Different classifications are available and the last one corresponds to the WHO 2010 version, which individualizes pseudomyxoma peritonei in two classes: low grade and high grade mucinous carcinoma. The very low frequency of this entity and its specific therapeutic strategy need specific health care centres, as well as physicians and pathologists collaborating through dedicated networks. The aim of this article is to summarize the pathology, causes, mechanisms and therapeutic approaches of pseudomyxoma peritonei, as well as their interfaces with dedicated networks.

Clinicopathological study of 25 cases of diverticular disease of the appendix: experience from farwaniya hospital

Background. Diverticular disease of the appendix (DDA) is a rare disease and it has been shown to be associated with locoregional neoplasms. This study was conducted to characterize clinicopathological features and to investigate its association with appendiceal neoplasms. Methods. We searched the records of the Department of Pathology at Farwaniya Hospital for cases of diverticular disease of the appendix between 2003 and 2011. Histological slides and patient charts were reviewed for relevant information. Consecutive cases of acute appendicitis were selected as a control group. Results. We identified 25 cases of DDA, 24 of which occurred in men. Mean age of DDA patients was 35 ± 10.1 years and was significantly greater than that of appendicitis patients (P = 0.027). The mean temperature of cases (37.9°) was significantly higher (P = 0.012) than that of the controls (37.3°). The cases had lower white blood cell (WBC) counts compared to controls (13.6 versus 16.7, P = 0.04). Pathological diagnosis identified 4 cases of diverticulosis, 5 cases of diverticulitis, 6 cases of diverticulosis with acute appendicitis, and 10 cases of diverticulitis and appendicitis. None of the cases was associated with any type of neoplasm. Conclusions. DDA is a rare disease, and clinicians and radiologists should be aware of it. Male sex and adult age seem to be risk factors associated with DDA. The disease may not have any direct association with any neoplasm.

Appendiceal Mucosal Schwann Cell Proliferation

Recognition of an appendiceal diverticulum is important because of its association with an appendiceal neoplasm. The incidence of mucosal Schwann cell proliferation in 24 cases of appendiceal diverticular disease, 17 serrated polyps, 4 cases of mucosal hyperplasia, and 45 normal appendices was determined. Ten (42%) of 24 cases with diverticula, 2 (50%) of 4 cases of mucosal hyperplasia with concurrent surface low-grade dysplasia, and 9 (20%) of 45 cases of normal appendices showed mucosal Schwann cell proliferation. It was not seen within the 17 cases of serrated polyps. Mucosal Schwann cell proliferation is common in appendiceal diverticular disease and may serve as a histologic marker for the presence of an appendiceal diverticulum. Thus, when routine histologic sections of a removed appendix demonstrate Schwann cell proliferation, further examination of the specimen may detect possible coexisting diverticular disease, which in turn may be associated with appendiceal neoplasms and epithelial dysplasia.

Clinical characteristics of acute appendiceal diverticulitis

Purpose

Diverticulitis of vermiform appendix is known as a rare cause of acute appendicitis, most of which are diagnosed after surgery. We compared appendiceal diverticulitis with acute appendicitis to study the clinical characteristics of appendiceal diverticulitis.

Methods

Among 1,029 patients who received appendectomy from January 2009 to May 2011, 38 patients with appendiceal diverticulitis (diverticulitis group) were compared with 98 randomly collected patients with acute appendicitis (appendicitis group) during the same period. Patients' characteristics, clinical features, laboratory findings, operative findings, and postoperative course were compared between the two groups.

Results

Thirty-eight patients (3.7%) were pathologically diagnosed with acute appendiceal diverticulitis among 1,029 cases of appendectomy. The mean age of patients in the diverticulitis group was significantly older than that of the appendicitis group (49.0 ± 15.2 years vs. 25.4 ± 14.2 years, P < 0.05). Mean duration of preoperative symptoms was longer in the diverticulitis group (3.6 ± 3.8 days vs. 1.8 ± 3.2 days, P < 0.05). The site of abdominal pain, fever, signs of localized peritonitis, accompanying gastrointestinal symptoms, and white blood cell count showed no differences between the two groups. Twenty-five patients (65.8%) of the diverticulitis group and 10 patients (10.2%) of the appendicitis group showed perforation of appendix (P < 0.05). Mean operating time and postoperative hospital stay were longer in the diverticulitis group (55.3 ± 28.8 minutes vs. 41.4 ± 17.8 minutes, 6.8 ± 3.4 days vs. 4.9 ± 1.5 days, P < 0.05).

Conclusion

Acute diverticulitis of the appendix can be classified into quite different disease entities compared with acute appendicitis. Regarding high rates of perforation, immediate surgical treatment is needed for patients with a high index of suspicion of acute diverticulitis of the appendix.

[Mucinous neoplasms of the vermiform appendix, Pseudomyxoma peritonei, and the new WHO classification]

Mucinous neoplasms of the appendix are rare tumors, some of them characterized by an enigmatic discrepancy between a benign morphologic appearance and an aggressive biologic potential, associated with a poor prognosis and high mortality. The clinical picture of pseudomyxoma peritonei is, with few exceptions, caused by mucinous appendiceal neoplasms and differs in many aspects from usual peritoneal carcinomatosis. The controversy regarding terminology, diagnostic criteria, classification and therapy of these tumors has lasted for decades. The revised edition of the World Health Organization Classification of Tumors of the Digestive System proposes a uniform reporting system for mucinous appendiceal neoplasms and the peritoneal disease associated with it, thereby creating a comparable basis for pathological diagnosis, clinical therapy and further scientific studies.

Significance of acquired diverticular disease of the vermiform appendix: a marker of regional neoplasms?

AIM

To assess the prevalence of acquired diverticulum of the appendix (DA), including incipient forms and its possible significance as a marker of local/regional neoplasms.

MATERIALS AND METHODS

The pathology database at Hvidovre Hospital was searched for appendix specimens, received between 2001 and 2010, coded for DA or for a space-occupying lesion. Slides were reviewed to determine DA status and the nature of lesions possibly causing DA.

RESULT

Among 4413 appendix specimens, DA were identified in 39 (0.9%, CI 0.6% to 1.2%) cases, 17 (43.6%, 28.0% to 59.2%) of which additionally harboured an appendiceal neoplasm/neoplastic precursor, whereas this figure was 1.2% (CI 0.9% to 1.6%) for non-DA specimens (p<0.0001). Six of the 39 DA specimens comprised incipient DA, three of which coexisted with appendiceal neoplasms. In addition, local/regional non-neoplastic lesions (six cases) and colorectal carcinomas (four cases) coexisted with DA.

CONCLUSION

DA has significance as a putative marker of local/regional neoplasms. Therefore, a DA specimen proved significantly more likely to harbour a neoplastic growth than a non-DA counterpart. Submission for microscopy of the entire DA specimen, whether transmural or only incipient, and a comment in the pathology report on the occasional concurrence of local/regional neoplasms in this setting seem appropriate. The observation of DA may thus provide a valuable contribution in the diagnostic process.

Epithelial neoplasms of the appendix

CONTEXT

The appendix gives rise to an array of epithelial neoplasms showing glandular or neuroendocrine differentiation, and some tumors with elements of both cell types. Although some appendiceal neoplasms resemble their counterparts in the small and large intestines (conventional adenocarcinoma and carcinoid tumor), the appendix also gives rise to relatively unique entities including mucinous neoplasms and goblet cell carcinoid tumors, which present a challenge in pathologic classification and clinical management.

OBJECTIVE

To review clinical and diagnostic issues for 3 pathologic types of epithelial neoplasms of the appendix: (1) adenocarcinoma, with specific focus on mucinous neoplasm; (2) goblet cell carcinoid tumor and associated adenocarcinoma; and (3) typical carcinoid tumor.

DATA SOURCES

Case-derived material and literature review.

CONCLUSIONS

The most important issue in pathologic assessment of epithelial tumors of the appendix is to understand the clinical implications inherent in the diagnosis.