A dangerous allergic reaction called anaphylaxis, where blood pressure drops suddenly, was rarely a sign of systemic mastocytosis (SM) in Southeast Asian patients, according to a recent study published in the Journal of Asthma and Allergy.
A severe allergic reaction in adults — especially one that causes fainting, a dangerous drop in blood pressure and no skin rash — is now seen as a warning sign that a person may have a hidden mast cell disorder like SM. However, most of what doctors know about the link between severe allergic reactions and mastocytosis comes from studies done in Europe, mostly in patients who had serious reactions to insect stings. Until now, no studies from Southeast Asia had looked at how often this condition is found in patients sent to a doctor for suspected mast cell problems.
In this study, doctors looked at 24 patients over five years at a hospital in Bangkok, Thailand. In the group that came in with anaphylaxis, only one out of 14 patients — about 7% — had SM.
The remaining 10 patients suspected of having mast cell problems had gone to the hospital for other reasons, such as unexplained low blood cell counts, an enlarged spleen, abnormal bone marrow, persistent skin rashes that looked like mastocytosis, or long-lasting stomach problems or tiredness. In this group, all 10 patients had mastocytosis: six had SM and four had a milder form called cutaneous mastocytosis, which affects only the skin.
Compared to patients without mastocytosis, patients with mastocytosis tended to be older, mostly male and had higher levels of a protein called tryptase in their blood.
Based on these findings, the study’s authors said doctors should not automatically do expensive bone marrow tests on everyone with allergic reactions. Instead, they should use special scoring tools to pick the patients most likely to have mastocytosis.
Read more about SM signs and symptoms
All 24 patients also had special DNA testing done to look for gene changes linked to SM. The pattern of gene changes seen in SM patients — including KIT D816V along with frequent changes in TET2, DNMT3A and SRSF2 — looks very similar to patterns seen in SM patients from Western countries. This suggests that “KIT-targeted therapies are biologically applicable in Thai patients,” the study’s authors said.
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