Appendiceal Pathology

On this page

Acute Appendicitis - Inflamed & Irate

  • Etiology: Luminal obstruction. Common causes: fecalith (adults), lymphoid hyperplasia (children), carcinoid, parasites.
  • Pathogenesis Flow:
  • Clinical Features:
    • Pain: Periumbilical (visceral) → RIF (somatic, McBurney's point).
    • Systemic: Anorexia, Nausea/Vomiting, low-grade Fever.
    • Signs: Localized RIF tenderness, Rebound tenderness, Guarding. Special signs: Rovsing's, Psoas, Obturator.
  • Diagnosis:
    • Alvarado Score (📌 MANTRELS) aids: Score ≥7 high probability.
      • (M:Migration, A:Anorexia, N:N/V, T:Tenderness RIF, R:Rebound, E:↑Temp(>37.3°C), L:Leukocytosis(>10,000/μL), S:Shift to left(>75%))
    • Labs: ↑WBC (neutrophilic leukocytosis), ↑CRP.
    • Imaging: USG (appendix >6mm diameter, non-compressible, wall thickening, target sign); CT (most accurate: fat stranding, complications).
  • Pathology (Gross & Micro):
    • Gross: Swollen, erythematous, dull serosa; fibrinopurulent exudate.
    • Micro:

      ⭐ Neutrophilic infiltration of the muscularis propria is the pathognomonic histological hallmark.

      • Edema, vascular congestion, mucosal ulceration, transmural inflammation and necrosis. Acute appendicitis histopathology: neutrophils
  • Complications: Perforation, peritonitis (localized/generalized), appendiceal abscess/phlegmon, pylephlebitis.

Appendiceal Neoplasms - Sneaky Surprises

  • Often incidental; may mimic appendicitis or present as mass/PMP.
  • Neuroendocrine Tumors (NETs/Carcinoids)
    • Most common; often at appendix tip.
    • Size critical: <1cm excellent prognosis; <2cm & no mesoappendiceal invasion usually benign course.
    • Markers: Chromogranin A, Synaptophysin.
  • Mucinous Neoplasms
    • Spectrum: LAMN → HAMN → Mucinous Adenocarcinoma.
    • Low-Grade Appendiceal Mucinous Neoplasm (LAMN):
      • Bland cells, pushing border; risk of Pseudomyxoma Peritonei (PMP) if ruptured.
    • High-Grade Appendiceal Mucinous Neoplasm (HAMN): More atypical cells, higher risk.
    • Mucinous Adenocarcinoma: Invasive, desmoplastic, poorer prognosis.
  • Goblet Cell Adenocarcinoma (GCA)
    • Aggressive; mixed glandular & neuroendocrine features. 📌 "Goblet cells gone rogue: a dangerous duo."
  • Pseudomyxoma Peritonei (PMP)
    • "Jelly belly" from mucinous ascites, often due to ruptured appendiceal mucinous neoplasm (esp. LAMN).
  • Non-Mucinous Adenocarcinoma
    • Colonic-type adenocarcinoma; generally poorer prognosis than NETs.

⭐ Appendiceal NETs <2cm without mesoappendiceal invasion are often cured by appendectomy alone. Appendiceal neuroendocrine tumor histopathology

Mucocele & Other Lesions - Appendix Oddities

  • Mucocele: Grossly dilated appendix, mucin-filled.
    • Types:
      • Simple Mucocele: Obstruction (e.g., fecalith).
      • Mucinous Hyperplasia: No atypia.
      • Mucinous Cystadenoma: Benign, low-grade atypia.
      • Mucinous Cystadenocarcinoma: Malignant, invasive.
    • Risk: Rupture → Pseudomyxoma Peritonei (PMP) - gelatinous peritoneal material.

      ⭐ PMP: Gelatinous ascites from ruptured appendiceal mucinous neoplasms (LAMN/cystadenocarcinoma).

  • Neuroendocrine Tumors (NETs/Carcinoids):
    • Most common appendiceal tumor, often at tip.
    • Often incidental. Good prognosis if < 2 cm, non-angioinvasive, no meso-extension.
    • Markers: Chromogranin A, Synaptophysin. Appendiceal Mucocele: Gross and Histology
  • Adenocarcinoma:
    • Rare, aggressive, colonic type.
  • Lymphoma:
    • Rare, usually Non-Hodgkin Lymphoma (NHL).
  • Diverticulosis/Diverticulitis:
    • Acquired outpouchings; inflammation can mimic appendicitis.

High‑Yield Points - ⚡ Biggest Takeaways

  • Acute appendicitis, the most common cause of acute surgical abdomen, is typically due to luminal obstruction (e.g., fecalith, lymphoid hyperplasia).
  • Key signs include periumbilical pain migrating to the RIF (Right Iliac Fossa) and McBurney's point tenderness.
  • Major complications are perforation, leading to peritonitis, and appendiceal abscess formation.
  • Neuroendocrine tumors (NETs/Carcinoids) are the most common appendiceal neoplasms, usually found incidentally at the tip.
  • Appendiceal mucocele (dilatation by mucin) can be benign or malignant; rupture of a mucinous neoplasm can cause pseudomyxoma peritonei (PMP).

Practice Questions: Appendiceal Pathology

Test your understanding with these related questions

During abdominal surgery under local anesthesia, the patient suddenly felt pain due to

1 of 5

Flashcards: Appendiceal Pathology

1/10

Acute gastritis may arise with severe _____ due to hypovolemia, which causes mucosal ischemia

TAP TO REVEAL ANSWER

Acute gastritis may arise with severe _____ due to hypovolemia, which causes mucosal ischemia

burns

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial