Beyond acute appendicitis: imaging of additional pathologies of the pediatric appendix

The Great Gut Mimicker: A case report of MIS-C and appendicitis clinical presentation overlap in a teenage patient

BACKGROUND

Abdominal pain and other gastrointestinal symptoms are common presenting features of multisystem inflammatory syndrome in children (MIS-C) and can overlap with infectious or inflammatory abdominal conditions, making accurate diagnosis challenging.

CASE PRESENTATION

We describe the case of a 16-year-old female who presented with clinical symptoms suggestive of appendicitis and an abdominal computed tomography (CT) that revealed features concerning for appendicitis. After laparoscopic appendectomy, histopathology of the appendix demonstrated only mild serosal inflammation and was not consistent with acute appendicitis. Her overall clinical presentation was felt to be consistent with MIS-C and she subsequently improved with immunomodulatory and steroid treatment.

CONCLUSIONS

We note that MIS-C can mimic acute appendicitis. This case highlights MIS-C as a cause of abdominal imaging with features concerning for appendicitis, and MIS-C should be considered in the differential for a patient with appendicitis-like symptoms and a positive COVID-19 IgG. Lab criteria, specifically low-normal white blood cell count and thrombocytopenia, appears to be of high relevance in differing MIS-C from acute appendicitis, even when appendix radiologically is dilated.

Not only appendicitis: rare appendix disorders manifesting as surgical emergencies in children

Acute appendicitis is the most common cause of acute abdominal pathology in children. However, other rare non-inflammatory non-neoplastic disorders involving the appendix may manifest as surgical emergencies. This study aimed to describe these atypical entities and present representative cases. The database of a tertiary children's medical center was reviewed for all the patients aged 0-18 years who underwent urgent appendectomy between June 2014 and December 2019, for rare disorders of the appendix unrelated to inflammatory or neoplastic processes. Of 1367 patients who underwent appendectomy, 1345 were operated urgently or emergently. Of these, six, all males, mean age 32.6 months (range 0.7-76), underwent appendectomy for rare surgical complications that involved the appendix. These included torsion of the appendix (2), a strangulated internal hernia through an appendicular ring (1) or through a mesoappendix gap (1), an incarcerated appendix in an acute hernia sac (1), and appendiceal intussusception (1). In all cases, the role of the appendix in the pathologic process was unexpected and came as a surprise to the surgeon. During a median follow-up of 4.2 months (range 1-8 months), one patient underwent relaparotomy for small bowel obstruction 4 weeks after the original procedure.Conclusion: The appendix in children can be the source of rare pathological disorders that present as surgical emergencies. Familiarity with these entities may aid in achieving accurate preoperative diagnosis and contribute to surgical team orientation on exploratory laparotomy. However, correct diagnosis is often only established during timely surgical intervention.

Ultrasound of the pediatric appendix

Appendicitis is the most common pediatric surgical emergency. Ultrasound (US) receives the highest appropriate rating scale in children with right lower quadrant pain suspected to have appendicitis. The US exam of the appendix has improved since Puylaert pioneered the technique of graded compression in 1986. In this article, we review ultrasonography of the pediatric appendix as it pertains to the normal appendix, acute appendicitis and the different sonographic manifestations. We also briefly describe technical optimization of image acquisition, common pitfalls and differential diagnoses.

Appendiceal ganglioneuroma in neurofibromatosis type 2

Here we report the case of a 30-year-old woman with a history of neurofibromatosis type 2 (NF2) who presented with an incidentally discovered pelvic mass on an ultrasound. The identity of the mass remained indeterminate following a CT and MRI, although appendiceal pathology was suspected. An elective laparoscopy and appendectomy were performed without complication and pathology on the specimen demonstrated an appendiceal ganglioneuroma. To our knowledge, there has been no prior documented case of an appendiceal ganglioneuroma in a patient with NF2. Furthermore, the current case is the first to report the MR characteristics of appendiceal ganglioneuromas.

Measurement error in CT assessment of appendix diameter

BACKGROUND

Appendiceal diameter continues to be cited as an important criterion for diagnosis of appendicitis by computed tomography (CT).

OBJECTIVE

To assess sources of error and variability in appendiceal diameter measurements by CT.

MATERIALS AND METHODS

In this institutional review board-approved review of imaging and medical records, we reviewed CTs performed in children <18 years of age between Jan. 1 and Dec. 31, 2010. Appendiceal diameter was measured in the axial and coronal planes by two reviewers (R1, R2). One year later, 10% of cases were remeasured. For patients who had multiple CTs, serial measurements were made to assess within patient variability. Measurement differences between planes, within and between reviewers, within patients and between CT and pathological measurements were assessed using correlation coefficients and paired t-tests.

RESULTS

Six hundred thirty-one CTs performed in 519 patients (mean age: 10.9 ± 4.9 years, 50.8% female) were reviewed. Axial and coronal measurements were strongly correlated (r = 0.92-0.94, P < 0.0001) with coronal plane measurements significantly larger (P < 0.0001). Measurements were strongly correlated between reviewers (r = 0.89-0.9, P < 0.0001) but differed significantly in both planes (axial: +0.2 mm, P=0.003; coronal: +0.1 mm, P=0.007). Repeat measurements were significantly different for one reviewer only in the axial plane (0.3 mm difference, P<0.05). Within patients imaged multiple times, measured appendix diameters differed significantly in the axial plane for both reviewers (R1: 0.5 mm, P = 0.031; R2: 0.7 mm, P = 0.022).

CONCLUSION

Multiple potential sources of measurement error raise concern about the use of rigid diameter cutoffs for the diagnosis of acute appendicitis by CT.

Perforated appendicitis: an underappreciated mimic of intussusception on ultrasound

BACKGROUND

We encountered multiple cases in which the US appearance of ruptured appendicitis mimicked intussusception, resulting in diagnostic and therapeutic delay and multiple additional imaging studies.

OBJECTIVE

To explore the clinical and imaging discriminatory features between the conditions.

MATERIALS AND METHODS

Initial US images in six children (age 16 months to 8 years; 4 boys, 2 girls) were reviewed independently and by consensus by three pediatric radiologists. These findings were compared and correlated with the original reports and subsequent US, fluoroscopic, and CT images and reports.

RESULTS

All initial US studies demonstrated a multiple-ring-like appearance (target sign, most apparent on transverse views) with diagnostic consensus supportive of intussusception. In three cases, US findings were somewhat discrepant with clinical concerns. Subsequently, four of the six children had contrast enemas; two were thought to have partial or complete intussusception reduction. Three had a repeat US examination, with recognition of the correct diagnosis. None of the US examinations demonstrated definite intralesional lymph nodes or mesenteric fat, but central echogenicity caused by debris/appendicolith was misinterpreted as fat. All showed perilesional hyperechogenicity that, in retrospect, represented inflamed fat "walling off" of the perforated appendix. There were four CTs, all of which demonstrated a double-ring appearance that correlated with the US target appearance, with inner and outer rings representing the dilated appendix and walled-off appendiceal rupture, respectively. All six children had surgical confirmation of perforated appendicitis.

CONCLUSION

Contained perforated appendicitis can produce US findings closely mimicking intussusception. Clinical correlation and careful multiplanar evaluation should allow for sonographic suspicion of perforated appendicitis, which can be confirmed on CT if necessary.

MRI for clinically suspected pediatric appendicitis: case interpretation

As utilization of MRI for clinically suspected pediatric appendicitis becomes more common, there will be increased focus on case interpretation. The purpose of this pictorial essay is to share our institution's case interpretation experience. MRI findings of appendicitis include appendicoliths, tip appendicitis, intraluminal fluid-debris level, pitfalls of size measurements, and complications including abscesses. The normal appendix and inguinal appendix are also discussed.

Anatomical variants and pathologies of the vermix

The appendix may demonstrate a perplexing range of normal and abnormal appearances on imaging exams. Familiarity with the anatomy and anatomical variants of the appendix is helpful in identifying the appendix on ultrasound, computed tomography, and magnetic resonance imaging. Knowledge of the variety of pathologies afflicting the appendix and of the spectrum of imaging findings may be particularly useful to the emergency radiologist for accurate diagnosis and appropriate guidance regarding clinical and surgical management. In this pictorial essay, we review appendiceal embryology, anatomical variants such as Amyand hernias, and pathologies from appendicitis to carcinoid, mucinous, and nonmucinous epithelial neoplasms.