Pathology · Year 2 · from Pathology

Case 1: Acute Appendicitis - Classic Suppurative Inflammation

Patient Demographics

• Age: 22 years old
• Sex: Male
• Occupation: College student

Chief Complaint

"Sharp pain in my lower right abdomen for 12 hours"

History of Present Illness

A 22-year-old male presents to the emergency department with a 12-hour history of abdominal pain. The pain began as a dull ache around the umbilicus and has since migrated to the right lower quadrant, becoming progressively sharper and more intense. He reports nausea with one episode of vomiting and loss of appetite. He has not had any bowel movements since the pain began. He denies recent travel, sick contacts, or dietary indiscretions. He has no significant past medical or surgical history.

Physical Examination

• Vital Signs: BP 128/82 mmHg, HR 98 bpm, RR 18/min, Temp 38.4°C (101.1°F), SpO2 99% on room air
• General: Young male lying still, appears uncomfortable, guarding abdomen
• Abdomen:
• Inspection: Flat, no distension
• Auscultation: Decreased bowel sounds
• Palpation: Maximal tenderness at McBurney's point (right lower quadrant), positive rebound tenderness, positive Rovsing's sign (palpation of left lower quadrant causes pain in right lower quadrant)
• Positive psoas sign (pain with right hip extension)
• Rectal exam: Tenderness on the right side

Diagnostic Workup

Laboratory Studies:

Urinalysis: Normal (no WBCs, RBCs, or nitrites)

Imaging:

• CT Abdomen/Pelvis with contrast:
• Dilated appendix (12 mm diameter) with wall thickening
• Periappendiceal fat stranding
• No free air or abscess formation
• Small amount of free fluid in pelvis

Surgical Pathology (post-appendectomy):

• Gross: Swollen, erythematous appendix with fibrinopurulent exudate on serosal surface
• Microscopy:
• Transmural neutrophilic infiltration
• Mucosal ulceration and necrosis
• Fibrinopurulent exudate in lumen
• Congested blood vessels with marginating neutrophils
• Fibrin thrombi in small vessels

Pathology Correlation

This case demonstrates the classic features of acute suppurative inflammation:

1. Vascular Changes:

• Vasodilation causing erythema (rubor) and warmth (calor)
• Increased vascular permeability leading to edema (tumor)
• Neutrophil margination along vessel walls

1. Cellular Response:

• Neutrophil emigration (diapedesis) through vessel walls
• Accumulation of neutrophils at site of injury
• Release of lysosomal enzymes and reactive oxygen species

1. Chemical Mediators:

• Elevated CRP (acute phase reactant from IL-6 stimulation)
• Fever from endogenous pyrogens (IL-1, IL-6, TNF-alpha)
• Left shift (increased bands) from bone marrow release

1. Pattern of Inflammation:

• Suppurative pattern with pus formation (dead neutrophils, liquefied tissue)
• Fibrinous exudate on serosal surface

Clinical Image

Gross pathology of acute appendicitis showing a swollen, inflamed appendix with congested blood vessels and fibrinopurulent exudate on the serosal surface. The appendix demonstrates the cardinal signs of acute inflammation: redness (rubor) and swelling (tumor).

Image Source: Wikimedia Commons - "Acute Appendicitis" License: CC BY-SA 3.0 URL: https://commons.wikimedia.org/wiki/File:Acute_Appendicitis.jpg

Diagnosis

Acute Suppurative Appendicitis

Treatment

1. NPO status and IV fluid resuscitation
2. IV antibiotics (ceftriaxone and metronidazole)
3. Laparoscopic appendectomy performed within 12 hours
4. Post-operative recovery with advancement of diet
5. Discharged on post-operative day 1

Teaching Points

1. Acute inflammation follows a stereotyped sequence: vascular changes, cellular infiltration, chemical mediator release
2. Neutrophils are the hallmark cells of acute inflammation, arriving within 6-24 hours
3. The left shift (increased band forms) reflects accelerated bone marrow release of immature neutrophils
4. CRP and procalcitonin are acute phase reactants useful for monitoring inflammation
5. Suppurative inflammation produces pus containing dead neutrophils and represents the body's attempt to contain pyogenic bacteria
6. Classic presentation of appendicitis demonstrates periumbilical-to-RLQ migration due to visceral then parietal peritoneal inflammation

All cases for this lecture as Markdown