Pathologic Analysis of Twenty-one Appendices From Children With Multisystem Inflammatory Syndrome Compared to Specimens of Acute Appendicitis: A Cross-sectional Study.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a rare, severe complication of coronavirus disease 2019, commonly involving the gastrointestinal tract. Some children with MIS-C undergo appendectomy before the final diagnosis. There are several hypotheses explaining the pathomechanism of MIS-C, including the central role of the viral antigen persistence in the gut, associated with lymphocyte exhaustion. We aimed to examine appendectomy specimens from MIS-C patients and assess their pathologic features, as well as the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens. METHODS: In this cross-sectional study we included 21 children with MIS-C who underwent appendectomy. The control group included 21 sex- and age-matched children with acute appendicitis (AA) unrelated to SARS-CoV-2 infection. Histologic evaluation of appendiceal specimens included hematoxylin and eosin staining and immunohistochemical identification of lymphocyte subpopulations, programmed cell death protein-1 (PD-1) and SARS-CoV-2 nucleocapsid antigen. RESULTS: Appendices of MIS-C patients lacked neutrophilic infiltrate of muscularis propria typical for AA (14% vs. 95%, P < 0.001). The proportion of CD20+ to CD5+ cells was higher in patients with MIS-C (P = 0.04), as was the proportion of CD4+ to CD8+ (P < 0.001). We found no proof of SARS-CoV-2 antigen presence, nor lymphocyte exhaustion, in the appendices of MIS-C patients. CONCLUSIONS: The appendiceal muscularis of patients with MIS-C lack edema and neutrophilic infiltration typical for AA. SARS-CoV-2 antigens and PD-1 are absent in the appendices of children with MIS-C. These findings argue against the central role of SARS-CoV-2 persistence in the gut and lymphocyte exhaustion as the major triggers of MIS-C.

Pathological Assessment of the Appendix in Appendectomies Performed in Children.

BACKGROUND: Acute appendicitis is known as the most common diagnosis of acute abdomen leading to surgery. Therefore, timely diagnosis is of special importance. This study was conducted with the aim of pathological assessment of the appendix in appendectomies performed in children to determine the rate of negative appendectomies and the predictors of negative appendectomy and to evaluate the paraclinical tools used in the diagnosis of acute appendicitis. METHODS: This is a cross-sectional descriptive study. All children who underwent appendectomy at Shahid Motahari Hospital in Urmia from March 2021 to March 2022 were examined. The required data including demographic, paraclinical, and final pathology characteristics were collected and recorded. The investigated cases were classified into positive and negative appendectomy categories for comparison. RESULTS: Among 234 pathology samples of the appendix, 22 cases were related to accidental appendectomy. In addition, 11.3% of cases were negative appendectomy and 88.7% were positive appendectomy. The age range of 8 to 14 years and male gender were associated with a lower negative appendectomy rate (both P<0.001). Inflammatory (49.5%) and gangrenous appendicitis (30.2%) were the most commonly reported histopathologies. Sonography had a sensitivity of 84%, a specificity of 79%, and an overall diagnostic accuracy of 83%. CONCLUSION: A relatively significant number of accidental and negative appendectomies are performed. More careful investigation and the use of expectant and medical treatment instead of surgery, especially in females and young children, can be effective in improving diagnostic accuracy and preventing negative appendectomies.

Occult appendix pathology in patients undergoing colorectal cancer resection and prophylactic appendectomy.

BACKGROUND: The risk-benefit balance of prophylactic appendectomy in patients undergoing left colorectal cancer resection is unclear. The aim of this report is to assess the proportion of histologically abnormal appendices in patients undergoing colorectal cancer resection in a unit where standard of care is appendectomy, with consent, when left-sided resection is performed. METHODS: A retrospective study on a prospectively collected database was conducted in a single tertiary-care center. Overall, 717 consecutive patients undergoing colorectal cancer resection between January 2015 and June 2021 were analyzed. The primary outcome was the proportion of histologically abnormal appendix specimens at prophylactic appendectomy. The secondary outcome was complications from prophylactic appendectomy. RESULTS: Overall, 576/717 (80%) patients had appendectomy at colorectal cancer surgery. In total, 234/576 (41%) had a right-/extended-right hemicolectomy or subtotal colectomy which incorporates appendectomy, and 342/576 (59%) had left-sided resection (left-hemicolectomy, anterior resection or abdominoperineal excision) with prophylactic appendectomy. At definitive histology, 534/576 (92.7%) had a normal appendix. The remaining 42/576 (7.3%) showed abnormal findings, including: 14/576 (2.4%) inflammatory appendix pathology, 2/576 (0.3%) endometriosis, 8/576 (1.4%) hyperplastic polyp, and 18/576 (3.1%) appendix tumors, which encompassed six low-grade appendiceal mucinous neoplasms (LAMNs), three carcinoids, and nine serrated polyps. In the 342 patients who had prophylactic appendectomy, 10 (2.9%) had a neoplasm (two LAMN, three carcinoids, and five serrated polyps). There were no complications attributable to appendectomy. CONCLUSION: Occult appendix pathology in patients undergoing colorectal cancer resection is uncommon when prophylactic appendectomy was performed. However, approximately 3% of patients had a synchronous appendix neoplasm.

Incidence and clinical features of endometriosis in 2484 consecutive female patients undergoing appendectomy for suspected appendicitis-a retrospective analysis.

INTRODUCTION: Endometriosis is a common condition affecting 5 to 10% of women of childbearing age. The true incidence of endometriosis of the appendix is currently unknown. Since symptoms often overlap with those of acute appendicitis, endometriosis of the appendix presents a diagnostic challenge in the emergency department. This large retrospective study investigates the incidence and perioperative clinical, radiologic, and laboratory findings, as well as possible differences between patients with and without endometriosis. METHODS: Data from consecutive patients who underwent appendectomy for suspected appendicitis without a history of endometriosis were analyzed. Perioperative clinical, laboratory, perioperative, and histopathologic findings were compared between women with and without endometriosis. RESULTS: Between January 2008 and June 2023, 2484 consecutive patients without a history of endometriosis underwent urgent appendectomy for suspected appendicitis. Endometriosis was detected on histopathologic examination in 17 (0.7%) patients. Signs of appendicitis were found less frequently on ultrasound in the endometriosis group compared to the non-endometriosis group (23.4% vs. 61.5%; p = 0.002; OR = 0.193; 95% CI 0.063-0.593). There were no differences in physical examination findings, duration of symptoms, degree of inflammation, surgical outcomes, or complication rates. CONCLUSION: The incidence of endometriosis of the appendix in patients undergoing appendectomy for suspected appendicitis was higher than suggested by data from autopsy series and populations with biopsy-proven endometriosis. Patients with endometriosis of the appendix were less likely to have a positive ultrasound finding, but perioperative and histopathologic findings and severity of inflammation did not differ from patients without endometriosis, presenting diagnostic challenges for clinicians.

Compilation of Evidence Supporting the Role of a T Helper 2 Reaction in the Pathogenesis of Acute Appendicitis.

Despite being the most common abdominal surgical emergency, the cause of acute appendicitis (AA) remains unclear, since in recent decades little progress has been made regarding its etiology. Obstruction of the appendicular lumen has been traditionally presented as the initial event of AA; however, this is often the exception rather than the rule, as experimental data suggest that obstruction is not an important causal factor in AA, despite possibly occurring as a consequence of the inflammatory process. Type I hypersensitivity reaction has been extensively studied, involving Th2 lymphocytes, and cytokines such as IL-4, IL-5, IL-9 and IL-13, which have well-defined functions, such as a positive-feedback effect on Th0 for differentiating into Th2 cells, recruitment of eosinophils and the release of eosinophilic proteins and the production of IgE with the activation of mast cells, with the release of proteins from their granules. Cytotoxic activity and tissue damage will be responsible for the clinical manifestation of the allergy. AA histological features are similar to those found in allergic reactions like asthma. The intestine has all the components for an allergic immune response. It has contact with hundreds of antigens daily, most of them harmless, but some can potentially induce an allergic response. In recent years, researchers have been trying to assess if allergy is a component of AA, with their latest advances in the understanding of AA as a Th2 reaction shown by the authors of this article.

Expression of Calretinin in the Cecal Muscularis Interna: Observation and Hypothetical Relevance to Appendicitis.

BACKGROUND: The unexpected observation of calretinin immunoreactivity in smooth muscle cells in the muscularis propria of the cecum led to a more detailed examination of calretinin expression and its possible relationship to propulsive contractile activity around the vermiform appendix. METHODS: Immunohistochemistry and RNA in situ hybridization were performed to analyze calretinin expression in intestinal samples from 33 patients at ages ranging from mid-gestation fetuses to adults, as well as in some potentially relevant animal models. Dual immunolabeling was done to compare calretinin localization with markers of smooth muscle and interstitial cells of Cajal. RESULTS: Calretinin expression was observed consistently in the innermost smooth muscle layers of the muscularis interna in the human cecum, appendiceal base, and proximal ascending colon, but not elsewhere in the intestinal tract. Calretinin-positive smooth muscle cells did not co-express markers located in adjacent interstitial cells of Cajal. Muscular calretinin immunoreactivity was not detected in the ceca of mice or macaques, species which lack appendices, nor in the rabbit cecum or appendix. CONCLUSIONS: Localized expression of calretinin in cecal smooth muscle cells may reduce the likelihood of retrograde, calcium-mediated propulsive contractions from the proximal colon and suppress pro-inflammatory fecal stasis in the appendix.

Nonneoplastic pathology of the appendix: A review article, based on the recent literature.

OBJECTIVES: The appendix, although considered a vestigial organ, is of considerable clinical importance because acute appendicitis is a common medical problem. There are also other disease processes involving the appendix. The appendix is among the first specimens that the pathologist (and surgeon) cuts one's teeth on. Thus, there may be a tendency to underestimate the clinically and prognostically significant appendiceal pathologies. METHODS: We provide a vade mecum of the pathologic features of a wide range of nonneoplastic appendiceal pathologies, with an emphasis on developing a practical approach to grossing, microscopy, and reporting-all with clinical and therapeutic implications. Much of this is based on literature on MEDLINE with reference to years 2008 to 2023, as well as on personal experiences and interpretations. RESULTS: The appendix can harbor a myriad of nonneoplastic pathologies, including infections, inflammations of varying etiologies (including interval appendectomy), endometriosis, diverticulosis, and so on. Chronic appendicitis, Crohn disease, and clinical audit are recurring themes while COVID-19 is a new entity. CONCLUSIONS: Most importantly, all pathologists should appreciate that the appendix is not as "routine" a specimen as one would want to believe.

Beneficios de la estandarización en el manejo de la apendicitis aguda / Benefits of standardization in the management of acute appendicitis

bjetivos. La apendicitis aguda (AA) es la patología quirúrgica pediátrica urgente más frecuente, pero su manejo postoperatorio es variable. La aplicación de protocolos minimiza esta variabilidad. Presentamos los resultados tras la optimización del protocolo de manejo en nuestro centro con objetivo de determinar su efectividad en cuanto a número de complicaciones infecciosas y optimización de recursos en nuestro medio. Material y métodos. Se realiza un estudio observacional retrospectivo en pacientes intervenidos de AA entre enero 2018 y agosto 2022. Comparamos dos cohortes, antes (1) y después del protocolo (2), subdividiéndolas según gravedad para un análisis por subgrupos: flemonosas (F), gangrenosas (G) y perforadas (P). Resultados. Incluimos 771 pacientes (1: 390/ 2: 381), con distribución homogénea, con mediana de edad 9,3 ± 2,8 años. La solicitud de analíticas previo al alta disminuyó de forma significativa (F: 3,9% vs. 0,5%; p= 0,026; G: 97,6% vs. 13,4%, p< 0,001). Los días de estancia hospitalaria se redujeron en los subgrupos F (1,2 IQR 0,7 vs. 1 IQR 0,36; p< 0,001), y G (4 IQR 1 vs. 3 IQR 1 días; p< 0,001). No se observaron diferencias en el número de abscesos entre los grupos (41 vs. 43 p= 0,73); sí en el subgrupo G (9 vs. 2; p= 0,029). Observamos una reducción del gasto de recursos en F y G. Conclusiones. En nuestro estudio, el subgrupo más beneficiado tras la optimización del protocolo fue el de las apendicitis gangrenosas con una reducción significativa en el número de complicaciones y en la utilización de recursos hospitalarios.(AU)

Objective. Acute appendicitis (AA) is the most frequent urgent surgical pathology in the pediatric population, but postoperative management is variable, with protocols minimizing variability. We present our results following the optimization of the management protocol in ourinstitution in order to establish its efficacy in terms of number of infectious complications and optimization of resources in our environment. Materials and methods. An observational, retrospective study of patients undergoing AA surgery from January 2018 to August 2022 was carried out. Two cohorts were compared, both before (1) and after (2) the implementation of the new protocol. They were divided according to severity in order to conduct a subgroup-based analysis –phlegmonous (PH), gangrenous (G), and perforated (P) appendicitis. Results. 771 patients (1: 390; 2: 381) were included, with a homogeneous distribution and a median age of 9.3 ± 2.8 years. Blood tests requested prior to discharge experienced a significant reduction (PH: 3.9% vs. 0.5%; p= 0.026; G: 97.6% vs. 13.4%, p< 0.001). Days of hospital stay decreased in the PH (1.2 IQR: 0.7 vs. 1 IQR: 0.36; p< 0.001) and G (4 IQR: 1 vs. 3 IQR: 1 days; p< 0.001) subgroups. No differences in the number of abscesses were found between groups (41 vs. 43; p= 0.73), but they were noted within subgroup G (9 vs. 2; p= 0.029). A reduction in resource expenses was detected in PH and G appendicitis. Conclusions. In our study, the most widely benefited subgroup following protocol optimization was the gangrenous appendicitis subgroup, with a significant reduction in the number of complications and the use of hospital resources.(AU)

Incidental appendiceal neoplasms: Single-centre results.

BACKGROUND: Histopathological examination of appendectomy specimens may reveal malignancies. Based on these results, either appendectomy is sufficient or sometimes a further treatment protocol can be needed. In this study, malignancy-diagnosed cases on appendectomy specimen were examined. METHODS: Patients who underwent appendectomy between January 2013 and December 2018 with a pre-diagnosis of acute appendicitis were evaluated retrospectively and those cases with malignancy were included in the study. Patients' age, sex, tumor type, tumor diameter, tumor grade, tumor localization, surgical margin, Ki-67 index, state of lymphovascular invasion, state of peri-neural invasion, and follow-up period duration were recorded. RESULTS: On examination of 2336 appendectomy specimens, 16 patients (0.7%) were found to have neuroendocrine tumors (NET), 11 patients (0.5%) were found to have low-grade mucinous neoplasm (LAMN), and five patients (0.2%) were found to have primary appendix carcinomas. Appendix tumors usually present with acute appendicitis symptoms. Despite re-operation with right hemicolectomy (RHC) being required in the treatment of adenocarcinoma cases, appendectomy provides adequate treatment in most cases with NET and LAMN. With these tumors, which usually have a benign prognosis, it is important to perform the necessary screening in the postoperative period and not to interrupt follow-up.

The human vermiform appendix: morphological and anatomical review.

The article covers aspects of morphological, anatomical, embryological, histological aspects and origin, types, blood supply, innervation, lymph drainage of human vermiform appendix. The purpose of the study is to understand real function and to summarize this information for positive impact on clinical decision in case of appendicitis. Although characteristic features of normal and diseased appendix have been reported for many previous centuries, it still the most common challenge facing every day in operation room. The appendectomy, commonest surgical emergency procedure, may cause little confusion in surgeons due to highly variable situations of it inside the abdominal cavity. However, the recent imaging techniques have increased ability of surgeon for crucial diagnosis of the diseased appendix.

Mucosal appendicitis: How can it be differentiated from nonappendicitis?

OBJECTIVES: Mucosal appendicitis is defined by neutrophilic infiltration limited to the mucosa, with no transmural invasion; it is currently a controversial entity. The aim of our study was to determine whether mucosal appendicitis represents an early stage of acute appendicitis (AA) or should be considered a negative appendectomy. METHODS: A retrospective study was performed of children with suspected AA who underwent surgical treatment between 2017 and 2020. The participants were divided into 2 groups according to histologic appendiceal findings: mucosal appendicitis (MA) and negative appendicitis (NA). Demographic, clinical, ultrasound, and laboratory features were compared between the groups. RESULTS: A total of 1269 patients with suspected appendicitis in whom appendectomy was performed were included, with a median age of 10.5 years. Mucosal appendiceal inflammation was histologically confirmed in 30 cases (MA group), while no inflammation or other pathologic findings were observed in 25 cases (NA group), with no differences in demographic, clinical, or ultrasound features between the groups. Those in the MA group presented with significantly higher leukocyte and neutrophil counts and higher neutrophil to lymphocyte ratios (NLRs) than those in the NA group (P < .001). The NLR was the parameter with the highest area under the curve (0.736) for the diagnosis of MA. A cutoff of 3.20 was established, with a maximum sensitivity and specificity of 62.5% and 78.9%, respectively. CONCLUSIONS: Mucosal appendicitis presents with laboratory and histologic inflammatory features that can be distinguished from nonappendicitis and should therefore be considered a pathologic entity within the spectrum of AA. Preoperative leukocyte and neutrophil counts and NLRs may help reduce the number of negative appendectomies.

Eosinophil Granule Proteins Involvement in Acute Appendicitis-An Allergic Disease?

Several pieces of evidence point to an allergic component as a trigger of acute appendicitis. As the Th2 immune response is characterized by eosinophil mobilization to the target organ and release of their cationic granule proteins, it is reasonable to investigate if the degranulation of eosinophils could be associated with the local injury. The primary aim of this study is to evaluate the participation of eosinophils granules proteins in acute appendicitis, both at local and systemic levels and the secondary aim is to evaluate the diagnostic accuracy of eosinophils granules proteins for the detection of acute appendicitis, as well as for distinguishing between complicated and uncomplicated acute appendicitis. Eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP) and eosinophil peroxidase (EP) are the most well-known eosinophil granule proteins. From August 2021 to April 2022, we present a prospective single-center study to evaluate the EDN, ECP, and EP concentrations simultaneously in appendicular lavage fluid (ALF) and the serum of 22 patients with acute phlegmonous appendicitis (APA), 24 with acute gangrenous appendicitis (AGA), and 14 normal controls. Concerning EDN, no differences were found between groups. ECP concentrations in ALF and serum were significantly higher in the histologically confirmed acute appendicitis compared to the control groups (p < 0.0001 and p < 0.0001, respectively). In ALF, no differences were found between ECP levels in APA: 38.85 ng/mL (IQR 26.50-51.77) and AGA 51.55 ng/mL (IQR 39.55-70.09) groups (p = 0.176). In the serum, no difference was found between ECP levels at APA: 39 ng/mL (IQR 21.30-56.90) and AGA: 51.30 ng/mL (IQR 20.25-62.59) (p = 0.100). For EP, the concentrations in ALF (p < 0.001) and serum (p < 0.001) were both higher in acute appendicitis compared to the control. In ALF, no difference was found between APA: 240.28 ng/mL (IQR 191.2-341.3) and AGA: 302.5 (IQR 227.7-535.85) (p = 0.236). In the serum, no differences were found between APA: 158.4 ng/mL (IQR 111.09-222.1) and AGA: 235.27 (IQR 192.33-262.51) (p = 0.179). Globally, the ALF concentrations were higher than serum concentrations, reflecting an intense inflammatory local reaction in AA. The optimal ECP cut-off for discriminating between acute appendicitis and the controls was >11.41 ng/mL, with a sensitivity of 93.5%, but with a specificity for identifying appendicitis of 21.4%, good discriminative power (AUC = 0.880). For EP, the optimal cut-off was >93.20 ng/mL, with a sensitivity of 87%, but with a specificity of 14.3% (AUC = 0.901), excellent discriminative power. For the diagnosis of perforated AA, the discriminative power of ECP and EP serum concentrations are weak (AUC = 0.562 and AUC = 0.664, respectively). Concerning the presence of peritonitis, the discriminative power of ECP and EP serum concentrations is acceptable, respectively: AUC = 0.724 and AUC = 0.735. Serum levels of EDN (p = 0.119), ECP (p = 0.586) and EP (p = 0.08) in complicated appendicitis were similar to uncomplicated appendicitis. Serum concentrations of ECP and EP can be added to decision-making AA diagnosis. A Th2-type immune response is present in AA. These data bring forward the role of an allergic reaction in the pathogenesis of acute appendicitis.

Analysis of surgical treatment of appendix neuroendocrine neoplasms-17 years of single-center experience.

BACKGROUND/AIM: This study investigated the clinicopathological characteristics and treatment of appendix neuroendocrine neoplasms in appendectomy specimens of our center. MATERIALS AND METHODS: The clinicopathological data, including age, sex, preoperative clinical manifestation, surgical method, and histopathological examination results of 11 patients with appendix neuroendocrine neoplasms confirmed by surgery and pathology between November 2005 and January 2023, were retrospectively analyzed. RESULTS: In the histopathological examination of 7277 appendectomy specimens, 11 cases (0.2%) had appendix neuroendocrine neoplasms. Among the 11 patients, 8(72.7%) were males, and 3(27.3%) were females, with an average age of 48.1 years. All patients underwent emergency surgery. A total of 9 patients underwent open appendectomy, including 1 patient who underwent second-stage simple right hemicolectomy after an appendectomy, and two who underwent laparoscopic appendectomy. All 11 patients were followed up for a period of 1 to 17 years. All patients survived without any indication of tumor recurrence. CONCLUSION: Appendiceal neuroendocrine neoplasms are low-grade malignant tumors originating from neuroendocrine cells. They are rarely seen in clinical practice and are often treated based on acute and chronic appendicitis symptoms. These tumors are challenging to diagnose before surgery due to the lack of specificity in clinical manifestations and auxiliary examinations. The diagnosis generally depends on postoperative pathology and immunohistochemistry. Despite the diagnostic challenges, these tumors have a favorable prognosis.

Diagnostic performance of magnetic resonance imaging for diagnosing acute appendicitis during pregnancy.

OBJECTIVE: This retrospective study evaluated the diagnostic efficacy of magnetic resonance imaging (MRI) for identifying acute appendicitis during pregnancy. PATIENTS AND METHODS: This retrospective study enrolled a total of 46 pregnant patients with clinically suspected acute appendicitis who underwent 1.5 T MRI and received a final pathological diagnosis. We evaluated the imaging characteristics associated with patients diagnosed with acute appendicitis, including the appendix diameter, the appendix wall thickness, intra-appendiceal fluid collection, and peri-appendiceal fat infiltration. A bright appendix on T1-weighted 3-dimensional imaging was identified as a negative sign for appendicitis. RESULTS: Peri-appendiceal fat infiltration had the highest specificity of 97.1% for diagnosing acute appendicitis, whereas increasing appendiceal diameter had the highest sensitivity of 91.7%. The cut-off values for increasing appendiceal diameter and appendiceal wall thickness were 6.55 mm and 2.7 mm, respectively. Using these cut-off values, appendiceal diameter had a sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of 91.7%, 91.2%, 78.4%, and 96.9%, respectively, whereas these values for appendiceal wall thickness were 75.0%, 91.2%, 75.0%, and 91.2%. The combination of increasing appendiceal diameter and appendiceal wall thickness resulted in an area under the receiver operating characteristic curve value of 0.958 with Se, Sp, PPV, and NPV values of 75.0%, 100.0%, 100.0%, and 91.9%, respectively. CONCLUSIONS: All five MRI signs examined in this study had significant diagnostic value for detecting acute appendicitis during pregnancy, with p-values <0.01. The combined use of increasing appendiceal diameter and appendiceal wall thickness displayed the excellent ability to diagnose acute appendicitis in pregnant women.

Acute appendicitis manifests as two microbiome state types with oral pathogens influencing severity.

Mounting evidence suggests that acute appendicitis (AA) is not one but two diseases: complicated appendicitis, which is associated with necrosis leading to perforation or periappendicular abscess, and uncomplicated appendicitis, which does not necessarily result in perforation. Even though AA is the most frequent cause of surgery from abdominal pain, little is known about the origins and etiopathogenesis of this disease, much less regarding the different disease types. In this study, we investigated the microbiome (inter-domain amplicon and metagenome sequencing) of samples from the appendix, rectum and peritoneum of 60 children and adolescents with AA to assess the composition and potential function of bacteria, archaea and fungi. The analysis of the appendix microbial community revealed a shift depending on the severity of the AA. This shift was reflected by two major community state types that represented the complicated and uncomplicated cases. We could demonstrate that complicated, but not uncomplicated, appendicitis is associated with a significant local expansion of oral, bacterial pathogens in the appendix, most strongly influenced by necrotizing Fusobacterium spp., Porphyromonas and Parvimonas. Uncomplicated appendicitis, however, was characterized by gut-associated microbiomes. Our findings support the hypothesis that two disease types exist in AA, which cannot be distinguished beyond doubt using standard clinical characterization methods or by analysis of the patient's rectal microbiome. An advanced microbiome diagnosis, however, could improve non-surgical treatment of uncomplicated AA.

Is acute appendicitis complicated or uncomplicated? Approaching the question via computed tomography.

BACKGROUND: The distinction between complicated and uncomplicated appendicitis is very important for the selection of the treatment method. PURPOSE: To investigate the sensitivity and specificity of computed tomography (CT) in differentiating between complicated and uncomplicated appendicitis to demonstrate that false negativity in differentiating these cases can be reduced when CT findings are incorporated into the clinical evaluation of patients. MATERIAL AND METHODS: All patients aged ≥18 years who underwent appendectomy at Malatya Training and Research Hospital in 2020 and 2021 were retrospectively screened. Of them, 283 patients were included in the study who had undergone CT before the operation. Patients with appendicitis were divided into two groups: complicated and uncomplicated, according to the results of their pathology tests. Demographic data, laboratory results, and CT images of the patients were evaluated. RESULTS: The patients with complicated appendicitis had a significantly higher mean age (P<0.001). The most common CT findings in patients with complicated appendicitis were moderate or severe peri-appendiceal fat stranding (PFS) and appendix wall enhancement defect (AWD). The findings with the highest sensitivity were PFS (77.9%) and AWD (69.4%). Although abscess, phlegmon, and peri-appendiceal air had the highest specificity (100%), these findings were the ones with the lowest sensitivity. According to the scoring system was developed for the differential diagnosis, CT had a sensitivity of 83.3% and a specificity of 79.2%. CONCLUSION: Based on the sensitivity and specificity values measured for CT according to the findings of our study, the scoring system may be useful for the differential diagnosis of complicated appendicitis.

IL-5 Serum and Appendicular Lavage Fluid Concentrations Correlate with Eosinophilic Infiltration in the Appendicular Wall Supporting a Role for a Hypersensitivity Type I Reaction in Acute Appendicitis.

Appendicitis is the most common abdominal surgical emergency, but its aetiology is not fully understood. We and others have proposed that allergic responses play significant roles in its pathophysiology. Eosinophils and Interleukin (IL)-5 are involved in a hypersensitivity type I reaction. Eosinophil infiltration is common in the allergic target organ and is dependent on IL-5. In the presence of an allergic component, it is expected that the eosinophil count and IL-5 local and systemic concentrations become elevated. To address this hypothesis, we designed a prospective study that included 65 patients with acute appendicitis (grouped as acute phlegmonous or gangrenous according to the histological definition) and 18 patients with the clinical diagnosis of acute appendicitis, but with normal histological findings (control group) were enrolled. Eosinophil blood counts and appendicular wall eosinophil infiltration were determined. IL-5 levels in blood and appendicular lavage fluid were evaluated. Appendicular lavage fluid was collected by a new methodology developed and standardized by our group. Appendicular wall eosinophil infiltration was higher in acute phlegmonous appendicitis than in gangrenous appendicitis (p = 0.000). IL-5 blood levels were similar in both pathologic and control groups (p > 0.05). In the appendicular lavage fluid, the higher levels of IL-5 were observed in the phlegmonous appendicitis group (p = 0.056). We found a positive correlation between the appendicular wall eosinophilic infiltration and the IL-5 concentrations, in both the blood and the appendicular lavage fluid, supporting the IL-5 reliance in eosinophil local infiltration. We observed the highest presence of eosinophils at phlegmonous appendicitis walls. In conclusion, the present data are compatible with a hypersensitivity type I allergic reaction in the target organ, the appendix, during the phlegmonous phase of appendicitis.

Diagnostic accuracy of computed tomography in adults with suspected acute appendicitis at the emergency department in a private tertiary hospital in Tanzania.

INTRODUCTION: The increasing incidence of acute appendicitis in sub-Saharan Africa emphasizes the need for accurate and reliable diagnostic tools. However, the variability in the diagnostic performance of computed tomography for suspected acute appendicitis coupled with comparatively higher negative appendectomy rates in this setting highlight a possible concern regarding the diagnostic accuracy. This study evaluated the diagnostic accuracy of a computed tomography scan for suspected acute appendicitis at the emergency department in Tanzania. METHODS: A retrospective diagnostic accuracy study was conducted from July to October 2020. All patients above 14 years of age who presented at the emergency department with right iliac fossa abdominal pain of fewer than ten days and underwent computed tomography for suspected acute appendicitis were evaluated, and the Alvarado score was computed. Histological diagnosis and clinical follow-up of 14 days were considered the reference standard. Ethical clearance was sought from the Aga Khan University Ethical review committee. RESULTS: 176 patients were included in this study. The sensitivity, specificity, and diagnostic accuracy were 100% (95% CI 91.8-100), 96.9% (95% CI 92.2-99.1), and 96.9% (95% CI 93.1-98.3), respectively. The mean Alvarado score in those without acute appendicitis was 4 (95% CI 3.7-4.3) compared to a mean score of 6.6 (95% CI 6.0-7.2) amongst those with acute appendicitis. The area under the receiver operator characteristics curve of computed tomography was 98.4%, and that of the Alvarado score was 84.1%. CONCLUSIONS: The diagnostic performance of computed tomography in this study is similar to that established elsewhere. However, the Alvarado score is not routinely used for the initial screening of suspected acute appendicitis patients. A threshold of Alvarado score of 4 as a guide to conduct computed tomography for suspected acute appendicitis would have decreased computed tomography use by 50%, and missed 4 cases. Implementation studies that address Alvarado score use should be conducted.

Interval Appendectomy Specimens.

CONTEXT.­: Patients with perforated appendicitis are often managed with antibiotic therapy followed by a delayed appendectomy. Histologic features of such specimens have been incompletely described, especially in the recent literature. OBJECTIVE.­: To describe the histomorphology of interval appendicitis with a focus on features that could mimic important conditions, such as infections, Crohn disease, and mucinous neoplasms. DESIGN.­: Histologic evaluation of 100 interval appendectomy specimens with clinical and radiologic correlation. RESULTS.­: A total of 54 of the 100 patients (54%) had radiologic evidence of appendiceal perforation, and 97% were treated with intravenous and/or oral antibiotic therapy prior to appendectomy. Percutaneous drains were placed in 34 cases (34%). Common histologic findings included mural eosinophilic infiltration (54%), periappendiceal fibrosis (54%), and xanthogranulomatous inflammation (31%). Periappendiceal fibrosis was frequent among patients with radiologic evidence of perforation. Nine cases (9%) featured pulse granulomata associated with fecal material. Epithelioid granulomata were detected in 6% of cases and were confined to mucosal lymphoid follicles in all cases. Only 4 of these were accompanied by mural lymphoid aggregates that raised the possibility of Crohn disease. Changes mimicking mucinous neoplasms were more common: 14% of cases (14 of 100) displayed goblet cell hyperplasia, 15% (15 of 100) contained diverticula, and 16% (16 of 100) showed mural or periappendiceal mucin pools. CONCLUSIONS.­: Although interval appendectomy specimens occasionally contain inflammatory infiltrates that mimic infections and/or Crohn disease, changes that can be confused with mucinous neoplasms are more frequently encountered.

PECULIARITIES OF MORPHOETIOPATHOGENESIS OF ACUTE APPENDICITIS AND CONSEQUENCES AFTER APPENDECTOMY.

OBJECTIVE: The aim: To study the features of morphoethiopathogenesis of acute appendicitis and the consequences after appendectomy. PATIENTS AND METHODS: Materials and methods: 10 preparations of human appendix were studied, from which 5 appendixes were normal in people who died in adulthood and old age and 5 processes were taken intraoperatively during appendectomy. Morphometric characteristics of the tissue structures of the preparations were compared with the systematic review data, the literature search by the following keywords: morphoethiopathy", "vermiform process", "lymphoepithelial formations", "digestive system", "lymphoid nodule", "Peyer's patches", "mucous membrane". RESULTS: Results: Pathogenesis of acute appendicitis - it is a consistent, staged process that is completely subject to the laws of exudative inflammation in response to microbial aggression. Removal of the appendicular process should be approached carefully and based on possible immunological consequences. Removal of the appendix as an immunocompetent organ Unreasonable removal of pathohistological unchanged appendix has medical consequences (can lead to consequences such as colon cancer) and not only. CONCLUSION: Conclusions: Our results suggest that the vermiform appendix retains its active function throughout human life. The study provides an overview with current knowledge about the etiology, pathogenesis and possible consequences of appendectomy as the main method of treatment of acute appendicitis. The search for ways to prevent appendicitis can be successful only by finding out the causes and factors that in some individuals cause the inability of the appendix to resist bacterial invasion. Appendix is necessary to fully support the immune responses of the digestive tract, but it belongs to the category of those organs, the loss of which during forced surgery does not cause significant damage to the body.