Pediatric Appendicitis

Etiology: occurs over 24-36 hours: hyperplasia of lymphoid follicles / parasites / neuroendocrine (carcinoid) tumor -> distension of appendix -> ischemic mucosal damage -> bacterial overgrown and wall invasion -> transmural inflammation -> perforation
AXR: appendicolith in 15%, may have distal small bowel obstruction
US Normal appendix: compressible blind ending tubular structure originating from base of cecum that does not have peristalsis, transverse diameter is < 6 mm, no wall thickening, central echogenic line which is acoustic reflection from collapsed luminal interface, 80% draped over iliac vessels
— Note: terminal ileum can mimic appendix but has hypoechoic folds and has peristalsis
US Acute appendicitis: noncompressible blind ending tubular structure with transverse diameter > 6 mm, appendiceal wall thickness > 3 mm, hyperemia on color doppler US, periappediceal hypoechoic halo from wall edema, periappendiceal hyperechogenicty of periappendiceal fat in mesentery from periappendiceal edema, appendicolith
— Note: diameter should not be only criteria, some say appendiceal transverse diameter of 6-8 mm is indeterminate for acute appendicitis and that appendiceal transverse diameter of > 8 mm is diagnostic of acute appendicitis
US Perforated appendicitis: appendix may not be seen or may be decompressed with diameter < 6 mm, phlegmon with poorly defined bowel loops in right lower quadrant with increased echogenicity, mass of mixed echogenicity, focal bowel wall thickening, intraperitoneal fluid, loculated fluid, frank abscess
CT Acute appendicitis: diameter > 8 mm (diameter 6-8 mm is indeterminate), enhancing, appendicolith in 30%, periappendiceal fat stranding, periappendiceal fluid / abscess are signs of perforation
MR Normal appendix: less than 7 mm, no periappendiceal changes, paucity of fat can make visualization difficult so lack of inflammatory changes implies a normal exam
MR Acute appendicitis: diameter > 7 mm, periappendiceal inflammation, focus of diminished signal intensity represents and appendicolith
Clinical:
— Simple appendicitis: periumbilical pain that localizes to right lower quadrant with fever and vomiting is seen in < 50% of patients, 33% of patients have nonspecific symptoms
— Perforated appendicitis: pain relief then more generalized pain and fever and generalized peritonitis

Radiology Cases of Appendicitis

Radiology Cases of Normal Appendix

CT of normal appendix — Axial CT with intravenous and oral contrast of the abdomen shows a non-dilated tubular structure originating from the cecum filled with oral contrast and lying on top of the right psoas muscle with no inflammatory changes around it.

Radiology Cases of Acute Appendicitis With Appendicolith

AXR of appendicolith — AXR AP shows an oval-shaped calcification in the right lower quadrant just above the right iliac crest at the level of the L4 vertebral body.

AXR of appendicoliths — AXR supine shows two round radiopaque objects projecting over the right side of the middle and lower sacrum.

US of acute appendicitis with appendicolith — Sagittal US of the right lower quadrant (above) shows a dilated, non-compressible, blind ending tubular structure measuring 10 mm in diameter with an echogenic focus at its tip causing posterior shadowing. Transverse US of the cecum (below) shows it to be thickened in appearance.

CT of acute appendicitis — Axial CT with contrast of the abdomen shows in the right lower quadrant an extremely large, fluid-filled, tubular structure containing several punctate calcifications within it and having some inflammatory changes surrounding it.

Radiology Cases of Acute Appendicitis

US of acute appendicitis — Transverse US of the right lower quadrant (above) shows a dilated, blind ending, non-compressible tubular structure (between the calipers) that is draped across the right psoas muscle and whose tip lies just above the right iliac vessels. Sagittal US of the right lower quadrant (below) showed the tubular structure to have a diameter of 9 mm

US of acute appendicitis — Sagittal US of the right lower quadrant shows a noncompressible blind ending J-shaped tubular structure (in the upper half of the image) with a transverse diameter of 8 mm with periappendiceal hyperechogenicty of the periappendiceal fat.

Radiology Cases of Acute Appendicitis in Morgagni Hernia

CXR of Morgagni Hernia that contained acute appendicitis — CXR PA shows the right heart border to be obscured and the lateral shows loops of bowel rising above the diaphragm anterior to the heart.

Radiology Cases of Acute Appendicitis and Carcinoid Tumor of the Appendix

CT of carcinoid tumor of the appendix — Axial CT with contrast of the abdomen (above) shows on top of the right psoas muscle and right iliac vessels in the right lower quadrant a dilated, fluid-filled tubular structure containing a calcification . Coronal CT (below) shows two calcifications within the tubular structure which is just medial to the cecum and surrounded by inflammatory changes.

Radiology Cases of Perforated Appendicitis

AXR of small bowel obstruction due to perforated appendicitis — AXR supine (left) shows multiple dilated loops of small bowel that have air fluid levels on the AXR upright (right). There is also a suggestion of a soft tissue mass in the right lower quadrant which is displacing the bowel loops medially.

CT of perforated appendicitis — AP radiograph of the right femur was unremarkable. Coronal STIR MRI of the right hip and femur was unremarkable aside from incidental bright pelvic free fluid noted just above the bladder. Coronal 2D reconstruction from a CT with IV and oral contrast of the abdomen shows a large complex fluid collection containing air and a central calcification in the right lower quadrant which was lying next to the psoas muscle.

Radiology Cases of Perforated Appendicitis With Appendicolith

US and CT of acute appendicitis with perforation with an appendicolith and a pelvic abscess — Sagittal US of the right lower quadrant (above left) shows a dilated, non-compressible, blind ending tubular structure between the calipers while a transverse US of the right lower quadrant (above right) shows echogenic fat surrounding an oval echogenic structure in the center of the image that has posterior shadowing. Axial CT with intravenous and oral contrast of the abdomen (below) shows a large cystic and septated mass in the center of and to the right of the pelvis that has an oval calcification in it anteriorly.

Surgery Cases of Appendicitis

Surgical image of acute appendicitis — Surgical image shows the appendix to be grossly inflamed with exudate, but not to be perforated.

Gross Pathology Cases of Appendicitis

Pathologic image of acute appendicitis with appendicoliths — Pathological image with the appendix opened longitudinally shows it to be grossly inflamed with two appendicoliths within the lumen of the appendix.

Histopathology Cases of Appendicitis

Histopathology image of acute appendicitis — Histopathological image of lower power, H&E stained section shows transmural inflammation with mucosal ulceration and serosal reaction with acute inflammatory exudate.

Histopathology image of acute appendicitis — Histopathological image of higher power H&E stained section shows the prominence of neutrophils.