What is the relationship between Mast Cell Activation Syndrome (MCAS) and acute appendicitis?

From the Guidelines

Mast cell activation syndrome (MCAS) patients undergoing acute appendicitis surgery should receive premedication with H1 blockers, H2 blockers, and corticosteroids, and the surgical team should be prepared for potential mast cell reactions with emergency medications readily available. This approach is necessary because surgical stress and medications can trigger mast cell degranulation in MCAS patients, releasing histamine and other inflammatory mediators that can cause symptoms ranging from flushing and hives to life-threatening anaphylaxis 1.

Key Considerations

• Patients with MCAS should inform their surgical team about their condition before appendectomy, as they have higher risks for anaphylactic reactions during surgery 1.
• Premedication is recommended, typically including H1 blockers (diphenhydramine 25-50mg), H2 blockers (famotidine 20mg), and corticosteroids (prednisone 40-60mg) administered 1-2 hours before surgery.
• During the procedure, the anesthesiologist should avoid known MCAS triggers like certain anesthetics, antibiotics, and NSAIDs, with preference for medications the patient has previously tolerated.
• Patients should continue their regular MCAS medications up to surgery and bring rescue medications (epinephrine auto-injector) to the hospital.
• Post-surgery, careful pain management is essential, often using acetaminophen rather than NSAIDs, and gradual tapering of any corticosteroids used.

Management of Acute Appendicitis

• The diagnosis and treatment of acute appendicitis should follow the updated guidelines, which recommend a single preoperative dose of broad-spectrum antibiotics in patients with acute appendicitis undergoing appendectomy 1.
• Non-operative management with antibiotics and percutaneous drainage may be considered for complicated appendicitis with peri-appendicular abscess, in settings where laparoscopic expertise is not available.
• Laparoscopic surgery is a safe and feasible first-line treatment for appendiceal abscess, being associated with fewer readmissions and fewer additional interventions than conservative treatment, with a comparable hospital stay.

Emergency Preparedness

• The surgical team should be prepared for potential mast cell reactions with emergency medications readily available, including epinephrine auto-injectors and other medications to manage anaphylaxis 1.
• In the event of anaphylaxis or other mast cell activation event, a full allergic workup should be initiated, including skin tests or detection of specific IgE antibodies and measurement of serum tryptase level.

From the Research

Mast Cell Activation Syndrome and Acute Appendicitis

• There is no direct evidence in the provided studies that links mast cell activation syndrome (MCAS) with acute appendicitis 2, 3, 4, 5, 6.
• However, it is known that MCAS can cause a range of gastrointestinal symptoms, including abdominal cramping, nausea, vomiting, and diarrhea 3, 6.
• These symptoms can be similar to those experienced by patients with acute appendicitis, which may lead to delays in diagnosis or misdiagnosis 3.
• The diagnosis of MCAS is based on a combination of clinical symptoms, laboratory tests, and response to treatment 2, 4, 5, 6.
• Patients with MCAS may experience systemic symptoms, including those affecting the gastrointestinal system, and may require a multidisciplinary approach to management 2, 3, 5.
• Further research is needed to understand the potential relationship between MCAS and acute appendicitis, as well as to develop effective diagnostic and treatment strategies for patients with MCAS who present with gastrointestinal symptoms 2, 3, 4, 5, 6.

Diagnostic Criteria for MCAS

• The diagnosis of MCAS is defined by three criteria:
  • Typical clinical signs and symptoms of acute, recurrent (episodic), and systemic mast cell activation (MCA) 4.
  • Increase in tryptase level to >20% + 2 ng/mL within 1-4 hours after onset of the acute crisis 4.
  • Response of MCA symptoms to antimediator therapy 4.
• Laboratory tests, such as serum tryptase levels and urinary or serum markers of mast cell activation, can support the diagnosis of MCAS 2, 4, 5, 6.

Management of MCAS

• The management of MCAS requires a personalized approach, taking into account the patient's underlying conditions, comorbidities, and symptoms 2, 3, 5.
• Treatment may involve antimediator therapy, mast cell stabilizers, and other medications to modulate mast cell activation and alleviate symptoms 2, 3, 4, 5, 6.