Appendix Anatomy and Anomalies Quiz

Appendiceal Anomalies

• First appendix position is normal; second appendix can arise at various colon sites.
• Type C anomaly involves complete duplication of the caecum, each with its own appendix.

Absence and Atresia

• Congenital absence of the appendix is rare and may be related to other abnormalities, like diaphragmatic hernia.
• Atresia can occur in the entire ileocaecal region.

Appendiceal Septa

• Formation of incomplete or complete septa within the appendiceal lumen, primarily seen in children and young adults.
• Factors contributing to septa: congenital abnormalities, post-inflammatory mucosal fusion, and ischaemia due to thrombosed vessels.

Diverticular Disease of the Appendix

• Congenital: involves a muscular wall structure.
• Acquired conditions, like cystic fibrosis, lack a muscular wall.

Fibrous Obliteration of Appendiceal Lumen

• Characterized by the presence of spindle cells within collagenous and myxoid background.
• The distal tip of the appendix is typically affected.

Acute Appendicitis

• Most common in adolescents and young adults but can occur in any age group, slightly more frequent in males.
• Preoperative diagnosis can be challenging.

Causes of Acute Appendicitis

• Obstruction leading to bacterial infection from sources such as faecoliths, foreign bodies, lymphoid hyperplasia, tumors, or mucin accumulation (including cystic fibrosis).
• Infection can be parasitic (e.g., amoebiasis, Cryptosporidium), bacterial (e.g., Yersinia), viral (e.g., EBV), or fungal (e.g., Candida).
• Involvement of inflammatory bowel disease and stump appendicitis is noted.

Pathogenesis of Acute Appendicitis

• Initiated by increased intraluminal pressure compromising venous outflow, leading to ischaemic injury.
• Results in bacterial proliferation and washing inflammatory responses, including neutrophilic infiltration.

Morphology in Early Acute Appendicitis

• Congestion of subserosal vessels and a perivascular neutrophilic infiltrate.
• Transition of serosa from glistening to dull, granular, and erythematous.
• Diagnosis requires neutrophilic infiltration of the muscularis propria with potential focal ulceration.

Later Stages of Appendicitis

• Formation of abscesses may occur (acute suppurative appendicitis), leading to hemorrhagic ulceration and potential gangrenous necrosis.
• Risk of rupture and subsequent suppurative peritonitis.

Clinical Features of Appendicitis

• Often asymptomatic; challenging diagnosis in young children and the elderly due to atypical presentations and other abdominal emergency causes.

Symptoms of Appendicitis

• Periumbilical pain migrating to the right lower quadrant, accompanied by nausea, vomiting, low-grade fever, and a mildly elevated white cell count.

Mucinous Cystadenoma

• Most common benign mucinous neoplasm replacing appendiceal mucosa.
• Luminal dilation may lead to perforation and mucus accumulation in the peritoneal cavity, typically without malignant cells.

Mucinous Cystadenocarcinoma

• Less common malignant neoplasm characterized by mucin-filled cystic dilatation indistinguishable from benign counterparts.
• Penetration of the appendiceal wall by invasive cells can lead to pseudomyxoma peritoneii and peritoneal dissemination.

Peritoneum Overview

• Composed of a single layer of mesothelial cells and connective tissue lining the peritoneal cavity, housing abdominal viscera.

Inflammatory Diseases of the Peritoneum

• Peritonitis can arise from bacterial invasion or chemical irritation due to various causes, including bile leakage and perforation of abdominal organs.

Infections in Peritonitis

• Bacterial peritonitis commonly follows perforation events, with typical sources including acute appendicitis and cholecystitis.
• Spontaneous bacterial peritonitis occurs without an obvious source, often seen in cirrhotic patients with ascites.

Morphological Changes in Peritonitis

• Initial infection leads to dull serosal surfaces and the accumulation of serous to creamy purulent fluid with neutrophils and fibrinopurulent debris.

Sclerosing Retroperitonitis

• Also known as idiopathic retroperitoneal fibrosis or Ormond disease, characterized by dense fibrosis and ureter compression.

Benign Lesions in the Abdomen

• Cysts can form in the abdominal cavity, potentially leading to palpable masses and various complications.

Test your knowledge on the anatomy of the appendix, including its normal position and rare abnormalities such as absence and atresia. This quiz will cover important concepts like appendiceal septa and complete duplication of the caecum.