What is mesoappendicitis?

Mesoappendicitis: Definition and Clinical Significance

Mesoappendicitis refers to inflammation of the mesoappendix, which is the fatty tissue containing blood vessels and lymphatics that supplies the appendix. This condition typically occurs in conjunction with appendicitis but can sometimes be the primary site of inflammation.

Anatomy and Pathophysiology

The mesoappendix is a fold of peritoneum that forms the suspensory ligament of the appendix. It contains:

• Appendicular artery (branch of ileocolic artery)
• Lymphatic vessels
• Adipose tissue
• Neural elements

Inflammation of the mesoappendix can occur through several mechanisms:

• Direct extension from appendicitis
• Primary inflammation due to localized infection
• Abscess formation within the mesoappendix
• Spread of bacteria through mesoappendiceal vessels

Clinical Significance

Mesoappendicitis has several important clinical implications:

1. Potential source of sepsis: Inflammation and abscess formation within the mesoappendix can lead to septic shock as bacteria can enter the bloodstream through mesoappendiceal vessels 1.

2. Tumor involvement: In cases of appendiceal neoplasms, the mesoappendix is commonly involved. Studies have shown that approximately 38% of patients with appendiceal tumors have direct or indirect tumor tissue within the mesoappendix 2.

3. Surgical considerations: During appendectomy, proper management of the mesoappendix is crucial for:

   • Adequate hemostasis
   • Complete removal of inflamed tissue
   • Preventing tumor spread in cases of neoplasms

Surgical Management

According to the World Society of Emergency Surgery (WSES) guidelines, there are several techniques for mesoappendix dissection during appendectomy 3:

• Monopolar electrocoagulation
• Bipolar energy devices
• Metal clips
• Endoloops
• LigaSure
• Harmonic Scalpel

The WSES recommends monopolar electrocoagulation and bipolar energy as the most cost-effective techniques for mesoappendix dissection, though other energy devices can be used based on surgeon preference and available resources 3.

Differential Diagnosis

Mesoappendicitis should be distinguished from other conditions affecting the mesentery:

1. Mesenteric adenitis: Characterized by enlarged lymph nodes in the right lower quadrant mesentery, often mimicking appendicitis. CT findings show clustered, enlarged mesenteric lymph nodes with a normal appendix 4.

2. Mesenteric panniculitis: A rare inflammatory disorder affecting the mesentery of the small bowel, appendix, and mesoappendix, characterized by nonspecific fibrous inflammation 5.

Clinical Implications and Management

When managing patients with suspected appendicitis:

1. Diagnostic approach: CT imaging can help identify inflammation extending to the mesoappendix.

2. Surgical approach: Laparoscopic appendectomy is strongly recommended over open appendectomy for both uncomplicated and complicated appendicitis 6.

3. Mesoappendix management: During appendectomy, complete removal of the mesoappendix is important, especially in patients ≥40 years old, due to the risk of appendicular neoplasms (3-17% in this population) 6.

4. Antimicrobial therapy: All patients diagnosed with appendicitis should receive appropriate antimicrobial therapy effective against facultative and aerobic gram-negative organisms and anaerobic organisms 3.

Conclusion

Mesoappendicitis is an important component of appendiceal pathology that can contribute to systemic complications and requires appropriate surgical management. Complete removal of the mesoappendix during appendectomy is recommended, particularly in older patients, to ensure adequate treatment and to rule out neoplastic involvement.