Distinguishing Features of MCAS and SLE

Clinical Presentation

The American Academy of Allergy, Asthma, and Immunology states that MCAS presents with acute, episodic, multi-system attacks resembling anaphylaxis that resolve between episodes, whereas SLE causes chronic, persistent inflammatory symptoms with organ damage that accumulates over time 1, 2, 3
MCAS requires recurrent episodic symptoms—not continuous ones, as stated by the American Academy of Allergy, Asthma, and Immunology 3
MCAS attacks are characterized by discrete episodes lasting minutes to hours, with symptom-free intervals between episodes 1, 2

MCAS requires concurrent involvement of at least 2 organ systems during acute episodes, including cardiovascular, dermatatologic, respiratory, and gastrointestinal systems 1, 2, 3
The American College of Allergy, Asthma, and Immunology recommends considering MCAS in patients with episodic symptoms involving multiple organ systems 1, 2

MCAS diagnosis requires documented acute increases in mast cell mediators during symptomatic episodes, including serum tryptase, urine N-methylhistamine, urine 11β-PGF2α, and urine LTE4 1, 2, 3
The American Academy of Allergy, Asthma, and Immunology states that baseline levels of mast cell mediators should normalize between episodes 3

MCAS diagnosis requires clinical response to mast cell-targeted therapies, including H1 and H2 antihistamines, leukotriene receptor antagonists, COX inhibitors, and mast cell stabilizers 1, 2, 3
The American College of Allergy, Asthma, and Immunology recommends using epinephrine for acute anaphylactic episodes in MCAS patients 5, 4