Comprehensive review of typical and atypical pathology of the appendix on CT: cases with clinical implications

"Rule out appendicitis": a Canadian emergency radiology perspective on medicolegal risks, imaging pitfalls, and strategies to improve care

We provide a unique Canadian perspective on the medicolegal risks associated with imaging acute appendicitis, incorporating data requested from the Canadian Medical Protective Association (CMPA) on closed medicolegal cases over the past decade. We include a review of current clinical and imaging guidelines in the diagnosis and management of this common emergency room presentation. A case-based approach is implemented in this article to explore ways to mitigate potential errors in the diagnosis of acute appendicitis.

[Multi-Detector CT Findings of Typical and Atypical Appendicitis: A Pictorial Essay]

Multi-detector CT (MDCT) is a highly accurate diagnostic tool that is commonly used to evaluate appendicitis and its complications. The diagnosis of appendicitis based on MDCT findings can be difficult and challenging when the observed findings are inconsistent with the typical features. Atypical appendicitis includes a wide spectrum of features, such as variable positions of the appendix and cecum, complications, and unusual pathological findings of secondary appendicitis that mimic or induce appendicitis. Our pictorial essay describes the diverse spectrum of atypical appendicitis and appendicitis-like conditions in terms of location abnormalities, complications, and uncommon pathologies, including related tumors, reactive appendicitis, appendiceal diverticulitis, and IgG4-related disease. Through this essay, the readers can become more familiar with MDCT findings of atypical appendicitis.

Update on acute appendicitis: Typical and untypical findings

Acute appendicitis is the most common indication for emergency abdominal surgery throughout the world and a common reason for consultation in emergency departments. In recent decades, diagnostic imaging has played a fundamental role in identifying acute appendicitis, helping to reduce the rate of blind laparotomies and hospital costs. Given the results of clinical trials supporting the use of antibiotic therapy over surgical treatment, radiologists need to know the diagnostic criteria for complicated acute appendicitis to be able to recommend the best treatment option. This review aims not only to define the diagnostic criteria for appendicitis in different imaging modalities (ultrasonography, computed tomography, and magnetic resonance imaging), but also to explain the diagnostic protocols, atypical presentations, and other conditions that can mimic appendicitis.

Review of appendicitis: routine, complicated, and mimics

Appendicitis is one of the most common sources of abdominal pain in the emergency setting and is generally considered a straightforward diagnosis. However, atypical appearances, non-visualization, and inconclusive features can make these cases more complicated. The objectives of this article are to review the differential diagnoses for right lower quadrant pain, discuss the imaging characteristics of simple appendicitis on computed tomography (CT), and provide guidance for equivocal cases, complicated appendicitis, and appendicitis mimics. This review will also discuss the identification and management of neoplasms of the appendix.

Appendiceal wall thickness and Alvarado score are predictive of acute appendicitis in the patients with equivocal computed tomography findings

Around 8-13% of the patients who underwent CT scan for diagnosis of appendicitis had equivocal CT results. About one-third of these patients had acute appendicitis and this caused diagnostic challenge to the clinicians. This study was conducted to identify clinical and imaging features that were predictive of acute appendicitis in patients who had equivocal CT findings. During January 2015 to June 2021, we retrospectively included 103 consecutive CT scans of adult patients (22 men and 81 women; mean age, 39.1 ± 17.5 years) who had equivocal CT findings of acute appendicitis. Two readers, blinded to the clinical data, independently assessed CT images for the relevant CT findings of appendicitis. Any disagreement between the readers was solved by consensus. The clinical parameters and CT findings were analyzed and compared between the patients who had appendicitis and patients who did not have appendicitis. Thirty-one (30.1%) patients had appendicitis, all of which were non-complicated. The appendiceal wall thickness of ≥ 2 mm and the Alvarado score of ≥ 7 were independent predictors of appendicitis with adjusted odds ratios (ORs) of 2.76 (95% CI, 1.09-7.02) and 1.47 (95% CI, 1.12-1.94), respectively. The maximal appendiceal diameter was higher in the appendicitis group (7.2 ± 1.2 mm vs. 6.5 ± 1.0 mm), but not predictive of appendicitis. The rest of the clinical parameters and CT findings, including mucosal hyperenhancement, periappendiceal fat reticulation, thickening of peritoneal reflection, appendicolith, focal cecal thickening, and content in appendiceal lumen showed no significant difference between two groups. The appendiceal wall thickness and the Alvarado score were able to predict appendicitis in patients who had equivocal CT findings.

Xanthogranulomatous appendicitis: A comprehensive literature review

BACKGROUND

Xanthogranulomatous inflammation is characterized histologically by a collection of lipid-laden macrophages admixed with lymphocytes, plasma cells, neutrophils, and often multinucleated giant cells with or without cholesterol clefts.

AIM

To review the medical literature on xanthogranulomatous appendicitis (XGA).

METHODS

We present a patient with XGA and review published articles on XGA accessed via the PubMed, MEDLINE, Google Scholar, and Google databases. Keywords used were “appendix vermiformis,” “appendectomy,” “acute appendicitis,” and “XGA.” The search included articles published before May 2020, and the publication language was not restricted. The search included letters to the editor, case reports, review articles, original articles, and meeting presentations. Articles or abstracts containing adequate information about age, sex, clinical presentation, white blood cells, initial diagnosis, surgical approach, histopathological and immunohistochemical features of appendectomy specimens were included in the study.

RESULTS

A total of 29 articles involving 38 patients with XGA, were retrospectively analyzed. Twenty (52.6%) of the 38 patients, aged 3 to 78 years (median: 34; IQR: 31) were female, and the remaining 18 (47.4%) were male. Twenty-five patients were diagnosed with acute appendicitis, ruptured appendicitis, or subacute appendicitis, and the remaining 13 patients underwent surgery for tumoral lesions of the ileocecal region. Twenty-two of the patients underwent urgent or semi-urgent surgery, and the remaining 16 patients underwent interval appendectomy.

CONCLUSION

Xanthogranulomatous inflammation rarely affects the appendix vermiformis. It is associated with significant diagnostic and therapeutic dilemmas due to its variable presentation. It is often associated with interval appendectomies, and a significant number of patients require bowel resection due to the common presentation of a tumoral lesion. XGA is usually identified retrospectively on surgical pathology and has no unique features in preoperative diagnostic studies.

Preoperative computed tomography is poor in detecting tumors of the appendix among patients with acute appendicitis: A cohort study of 5,224 appendectomies

BACKGROUND

Neoplastic processes are among the known etiologies for acute appendicitis. While conservative treatment with antibiotics alone has been proposed as a treatment for uncomplicated appendicitis, the presence of tumors should be excluded when offering patients this option. The aim of this study was to assess the accuracy of computed tomography (CT) in detecting appendiceal tumors.

METHOD

Consecutive patients operated on for acute appendicitis between January 2007 and October 3, 2018, in our university hospital were included. Whenever appendiceal tumor was histopathologically confirmed, CT interpretations and surgical reports were carefully reviewed. All CT scans were reanalyzed by consultant body radiologists. Discrepancies between the preliminary and final radiological interpretations were noted.

RESULTS

A total of 5,224 patients underwent appendectomy, of whom 4,766 had histopathologically confirmed acute appendicitis. Eighty-four patients (median, 61 (13-89) years; 54% female) were diagnosed with appendiceal tumor. Fifty-two patients (62%) had uncomplicated appendicitis. Although incidence of tumors was associated with older age, tumors were found in all ages. The share of tumors increased from 1.7% to 3.0%/year during the study. The most common tumors were neuroendocrine tumors (n = 33), low-grade appendiceal mucinous neoplasms (n = 14), and adenocarcinomas (n = 11). Sixty-one patients (73%) underwent preoperative CT. Computed tomography interpretation during on-call hours suspected tumor in only one case (3.4%) with invasive tumor, and in five cases (16%) with noninvasive tumor.

CONCLUSION

Appendiceal tumors are possible findings in appendix specimens, and most patients had uncomplicated acute appendicitis. In light of findings we conclude that CT cannot be used to exclude neoplastic etiology underlying acute appendicitis.

LEVEL OF EVIDENCE

Diagnostic, level IV.

Unfinished Business: A Systematic Review of Stump Appendicitis

BACKGROUND

Stump appendicitis is defined as interval inflammation of any residual appendicular tissue, after an appendicectomy. We present a systematic review of case series and case reports on stump appendicitis, emphasising on risk factors, diagnosis and surgical management.

METHODS

The English literature (1945-2018) was reviewed, using PubMed, Embase and GoogleScholar, combining the terms "appendix", "appendicitis", "stump", "residual", "recurrent" and "retained". In total, 127 studies were included, describing 164 patients (males 59%, mean age 36 ± 17 years).

RESULTS

Index surgery was open in 59% and laparoscopic in 38%. It was described as "difficult" or "complicated" in 31%. 20% of patients reported episodes of recurrent abdominal pain during the time interval between index and stump appendicitis (range 2 weeks to 60 years, median 2 years). Right lower quadrant pain was the most frequent complain (88%), leukocytosis was found in 56%, whereas 92% of patients underwent imaging testing, which was diagnostic or highly suspicious in 67.5%. Mean delay between beginning of symptoms and surgery was 2.4 ± 2.3 days. The operative approach was open in 61% and laparoscopic in 35% of cases. The operation was characterised as "difficult" or "complicated" in 45%. In the majority (88%), a completion stump appendicectomy was performed, with 11% requiring more extensive procedures. Mean length of resected stump was 3.1 ± 1.6 cm (range 0.5-10 cm).

CONCLUSIONS

Stump appendicitis may occur following both open and laparoscopic approach, when the residual stump is > 0.5 cm. Its clinical significance lies in the delayed diagnosis, leading to higher incidence of complications and the need for more extensive surgery.

Comparison of Appendectomy for Perforated Appendicitis With and Without Abscess: A National Surgical Quality Improvement Program Analysis

BACKGROUND

Outcomes of appendectomy stratified by type of complicated appendicitis (CA) features are poorly researched, and the evidence to guide operative versus nonoperative management for CA is lacking. This study aimed to determine laparoscopic-to-open conversion risk, postoperative abscess risk, unplanned readmission risk, and length of hospital stay (LOS) associated with appendectomy in patients with perforated appendicitis without abscess (PA) and perforated appendicitis with abscess (PAWA) compared with a control cohort of nonperforated appendicitis (NPA).

METHODS

The 2016-2017 National Surgical Quality Improvement Program Appendectomy-targeted database identified 12,537 (76.1%) patients with NPA, 2142 (13.0%) patients with PA, and 1799 (10.9%) patients with PAWA. Chi-squared analysis and analysis of variance were used to compare categorical and continuous variables. Binary logistic and linear regression models were used to compare risk-adjusted outcomes.

RESULTS

Compared with NPA, PA and PAWA had higher rates of conversion (0.8% versus 4.9% and 6.5%, respectively; P < 0.001), postoperative abscess requiring intervention (0.6% versus 4.8% and 7.0%, respectively; P < 0.001), readmission (2.8% versus 7.7% and 7.6%, respectively; P < 0.001), and longer median LOS (1 day versus 2 days and 2 days, respectively; P < 0.001). PA and PAWA were associated with increased odds of postoperative abscess (odds ratio [OR]: 7.18, 95% confidence interval [CI]: 5.2-9.8 and OR: 9.94, 95% CI: 7.3-13.5, respectively), readmission (OR: 2.70, 95% CI: 2.1-3.3 and OR: 2.66, 95% CI: 2.2-3.3, respectively), and conversion (OR: 5.51, 95% CI: 4.0-7.5 and OR: 7.43, 95% CI: 5.5-10.1, respectively). PA was associated with an increased LOS of 1.7 days and PAWA with 1.9 days of LOS (95% CI: 1.5-1.8 and 1.7-2.1, respectively).

CONCLUSIONS

Individual features of CA were independently associated with outcomes. Further research is needed to determine if surgical management is superior to nonoperative management for CA.

Reliability of standardized reporting system of acute appendicitis in adults at low-dose 320-rows CT

Aim

To assess the reliability of a standardized reporting system of acute appendicitis at low-dose 320-rows CT.

Subjects and Methods

Retrospective analysis CT of 78 patients with pathologically proven acute appendicitis. The study was performed at a low-dose 320-rows CT. The image analysis was performed by 2 radiologists according to a standardized reporting system of acute appendicitis.

Results

There was an excellent overall of the inter-observer agreement of both observers for the standardized reporting system of acute appendicitis (K = 0.89, 95 % CI = 0.87-0.92, P = 0.001). There was good inter-observer agreement for visualization of the appendix (K = 0.78, P = 0.001), the tip diameter (K = 0.75, P = 0.001), and a single wall thickness of appendix (K = 0.77, P = 0.001). There was excellent inter-observer agreement for outer to outer wall diameter (K = 0.82, P = 0.001), mucosal hyper-enhancement (K = 0.80, P = 0.001), appendicolith (K = 0.86, P = 0.001), gas in the appendix (K = 0.82, P = 0.001), surrounding fat stranding (K = 0.81, P = 0.001), focal cecal thickening (K = 0.85, P = 0.001), peri-appendiceal air (K = 0.87, P = 0.001), peri-appendicular fluid collection, phlegmon, or abscess (K = 0.82, P = 0.001), and right ovary cyst (K = 0.83, P = 0.001).

Conclusion

we concluded that excellent reliability of a standardized reporting system of acute appendicitis in the adults using low-dose 320-rows CT.

Identifying emergency pathology on abdominopelvic CT for non-radiologists

Abdominal and pelvic computed tomography (CT) scans can be complex to interpret but sometimes significant abnormalities are relatively easy to recognize. In emergencies it is beneficial if physicians and surgeons can identify significant pathology that may immediately change patient management. Early image interpretation will allow clinicians to alert radiologists to provide prompt urgent reports, facilitate early referral to other specialities or expedite emergency surgery. This article provides non-radiologists with a systematic approach to identifying emergency pathology on abdominal and pelvic CT scans. It reviews the relevant cross-sectional anatomy and discusses the CT appearances of bowel perforation, bowel obstruction, bowel ischaemia (gangrene), bleeding, appendicitis and hydronephrosis using illustrative examples from the authors' clinical practice. Underlying causes for these conditions and the importance of interpreting the radiological appearances in conjunction with the patient's clinical condition and history are discussed. The authors hope that by using the POGBAH acronym and a systematic approach readers will be able to identify emergency pathology on abdominal and pelvic CT which may improve patient care.