Low-magnification light microscopy of an appendix reveals a wall thickened by dense acute and chronic inflammatory infiltrate involving mucosa, submucosa, and portions of the muscularis. The lumen is variably compressed by edema and hemorrhage. Within the inflamed appendiceal wall, several Entamoeba histolytica trophozoites are evident in the center of the field; these trophozoites display pale cytoplasm and a small, dark nucleus, frequently containing ingested red blood cells, and are best appreciated on subsequent higher‑power images. The surrounding tissue shows neutrophilic and mononuclear inflammation, crypt destruction, and focal ulceration, consistent with amoebic appendicitis. Adjacent serosa may exhibit reactive edema. This histopathologic pattern supports a diagnosis of amoebic (Entamoeba histolytica) infection rather than typical bacterial appendicitis, with diagnostic significance for targeted anti-parasitic therapy (e.g., metronidazole) followed by luminal agents. Clinically, the finding correlates with acute abdomen symptoms, travel/ endemic exposure, and stool studies or serology. In differential considerations include bacterial gangrenous appendicitis, ischemic changes, and other intestinal parasites; normal variants are not present in this specimen. This image is a teaching example for surgical pathology, infectious disease correlation, and gastrointestinal parasitology education. Keywords: amoebic appendicitis, Entamoeba histolytica, parasitic appendicitis, histology, H&E, appendix, trophozoites. Educational resource for clinicians.

Imaging modality: light microscopy of hematoxylin and eosin stained appendix tissue, providing histopathologic confirmation of acute appendicitis. The specimen shows a cross-sectional or longitudinal histologic section of the appendix with transmural neutrophilic inflammation, most prominent in the muscularis propria, consistent with acute inflammatory process. Neutrophils are scattered in the mucosa and submucosa and form dense aggregates within the muscularis layer, with occasional microabscesses and disrupted tissue architecture. The lamina propria and mucosal glands are variably inflamed, and there is edema of the surrounding connective tissue with increased vascularity. The background stroma is pink and eosinophilic, with numerous dark-pigmented neutrophils and rare lymphocytes. The overall pattern supports acute appendicitis and correlates with clinical symptoms such as right lower quadrant pain, fever, leukocytosis. Pathologic significance: transmural neutrophilic infiltration denotes active infection of the appendix and raises concern for perforation if the process extends. Clinically, this image provides definitive diagnosis, guides surgical management, and informs postoperative antibiotic therapy. Differential considerations include early Crohn's disease involving the appendix, appendiceal diverticulitis, and secondary infectious or inflammatory processes. This image is relevant for medical education, pathology training, and research into inflammatory appendiceal disease. Clinical utility includes aiding diagnosis in equivocal cases and supporting teaching files for histology and surgical pathology.

Clinical photograph of an acutely inflamed vermiform appendix immediately following surgical excision (appendectomy). The specimen is approximately 8 cm in length and demonstrates classic morphological features of acute appendicitis. The serosal surface is intensely erythematous and congested with a reddish-pink hue. Notable pathological findings include diffuse edema resulting in a swollen, non-uniform diameter, and the presence of fibrinopurulent exudate across the irregular, moist surface. The distal portion appears more bulbous and distended. Small focal petechial hemorrhages (blood spots) are visible along the organ's length. The specimen is positioned against sterile surgical gauze and held by surgical instruments, illustrating the macroscopic appearance of suppurative appendicitis and periappendicitis for educational purposes in general surgery and pathology.

Gross pathology photograph of a surgically excised vermiform appendix demonstrating acute inflammatory changes. The serosal surface is markedly hyperemic with pronounced vascular congestion. A fibrinopurulent exudate coats the external surface in several locations, imparting a pale, shaggy sheen against the inflamed, deep-red background. The organ is edematous and friable, with thickened wall and irregular contours at the tip; luminal patency is not evident from this exterior view. These macroscopic appearances correspond to the classic gross features of acute appendicitis: mucosal edema, mural inflammation, and serosal exudation that may herald further complication if not treated. The specimen displays variable color due to surface moisture, focal ecchymosis, and vascular markings consistent with inflammatory hyperemia. The image is helpful for gross-pathology education, surgical-pathology correlation, and radiology-pathology teaching, illustrating how inflammatory exudates appear on the serosal surface and how appendix morphology changes in acute inflammation. Potential clinical implications include the need for prompt appendectomy to prevent progression to perforation or periappendiceal abscess. This visual also supports differential considerations such as phlegmonous appendicitis and atypical presentations, reinforcing the role of gross assessment in guiding subsequent histopathologic evaluation and clinical management. The image is valuable for student bedside teaching and pathology gallery resources. Consistently used worldwide.

This composite figure displays diagnostic imaging of the abdomen across three panels, illustrating the progression from acute appendicitis to postsurgical status. Panel A shows an ultrasound of the right lower quadrant (RLQ) featuring a blind-ending, non-compressible, tubular structure with a 'target' appearance in the transverse plane, measuring approximately 9 mm in diameter, indicative of acute appendicitis. Panel B is an axial CT scan of the pelvis with intravenous contrast following an appendectomy and terminal ileum resection. It demonstrates postsurgical changes in the right anterior abdominal wall, mild subcutaneous emphysema (air), and high-density, non-enhancing fluid collections in the cul-de-sac and prevesical space, suggesting a phlegmon or postsurgical fluid. Panel C presents a follow-up postsurgical ultrasound of the RLQ, highlighting localized free fluid and hyperechoic inflammatory changes in the mesenteric fat. These images collectively provide a clinical educational overview of radiological features associated with complicated appendicitis and typical postoperative radiological findings.

This dual-panel image demonstrates diagnostic imaging of acute obstructive appendicitis in a pediatric patient. Panel (a) is a grayscale ultrasound of the right lower quadrant, showing the abdominal wall layers and a deep, abnormal curved tubular structure. This structure features thickened, echogenic walls and internal speckling, with measurement calipers marking the diameter and length of the inflamed appendix. Panel (b) is an axial non-contrast computed tomography (CT) scan of the pelvis. It shows a cross-section of an enlarged appendix in the right lower quadrant containing multiple hyperdense (bright white) foci consistent with appendicoliths or fecaliths. The CT also highlights the surrounding soft tissue anatomy, pelvic bones (ilium, sacrum), and adjacent intestinal loops. Together, these modalities illustrate key radiological findings for appendiceal obstruction, including luminal distension, wall thickening, and the presence of obstructive high-density material.

This composite figure demonstrates the diagnostic imaging of acute appendicitis via Point-of-Care Ultrasound (POCUS) and Computed Tomography (CT). Image A is a high-frequency linear probe ultrasound showing a cross-section of a thickened, non-compressible appendix. Key features include a hypoechoic, edematous muscularis propria (indicated by a yellow arrow) and an intraluminal hyperechoic appendicolith/faecolith (white arrow) exhibiting prominent posterior acoustic shadowing (arrowheads). A localized anechoic fluid collection (marked 'F') surrounds the inflamed appendix, consistent with periappendiceal fluid or a phlegmon. Image B is an axial CT scan of the abdomen and pelvis with intravenous contrast, confirming the ultrasound findings in the right iliac fossa. It shows a dilated appendix with wall enhancement and an associated hyperdense faecolith (white arrow) situated anterior to the psoas muscle. This comparison illustrates the utility of POCUS in identifying classic sonographic signs of appendicitis—wall thickening, fecaliths with shadowing, and periappendiceal fluid—and its correlation with definitive CT imaging in a clinical setting of fever and right lower quadrant pain.