24
Management
XI. Anaphylaxis in Mastocytosis, Monoclonal Mast Cell
Activating Syndrome (MMAS), and Mast Cell Activating
Syndrome (MCAS)
Î Systemic mastocytosis and mast cell activating disorders can be
responsible for episodes of anaphylaxis that appear to be idiopathic in
nature. When there is a suspicion of one of these disorders, a baseline
serum tryptase should be done and one can also order a blood test
to screen for KIT 816V mutations, and if the diagnosis needs to be
corroborated based on these tests, a bone marrow can be done. In a
mast cell activating disorder, the bone marrow will show some findings
consistent with systemic mastocytosis but the diagnosis will not meet
all of the criteria required (Table 15).
Î SS 74: Recognize that patients with systemic mastocytosis (SM) or
MMAS are at increased risk for anaphylaxis. (S-B)
Î SS 75: Obtain a bone marrow biopsy specimen from patients
fulfilling the criteria for possible mast cell disease and perform
immunohistochemical staining with antibody directed to mast cell
tryptase, recognizing that demonstration of coexpressed CD2 and
CD25 in CD117 (KIT)-positive mast cells by flow cytometry of bone
marrow aspirates or immunohistochemical analysis of bone marrow
biopsy specimens provides the most sensitive and specific support for
the diagnosis of SM. (R-B)
Î SS 76: Treat anaphylaxis in a patient with SM, MMAS, or MCAS in
the same manner as anaphylaxis in a patient experiencing an SR to a
known allergenic substance. (S-D)
Î SS 77: Evaluate a patient with idiopathic anaphylaxis or insect
sting-induced anaphylaxis for SM if the patient has cutaneous
mastocytosis, unexplained organomegaly, an unexplained cytopenia
or thrombocytopenia, recurrent severe episodes of anaphylaxis, or an
elevated serum tryptase level obtained during a period when no SR is
recognized. (S-D)
Î SS 78: Provide patients with SM, MMAS, and MCAS with AIE to use in
the event of anaphylaxis. (S-D)
