Thank you for your inquiry.
I think it is important to understand that in adults, as many as 60 percent of cases of anaphylaxis have no known cause (1). So, the fact that a cause has not been detected by comprehensive testing does not rule out an exogenous exposure as the cause of anaphylaxis. It may not be an “allergy per se,” but can well be an external trigger that acts through another mechanism. However, there is a well known entity entitled “undifferentiated somatoform anaphylaxis.” Reports have appeared in the literature over the last few decades. We have seen several patients who have somatoform reactions which mimic anaphylactic events as described in the Choy, et al. abstract which is copied for you below. Establishing this diagnosis of course mandates that all other causes have been ruled out.
On the other hand, although neurogenic triggers for anaphylaxis have been reported intermittently in the literature, the relationship between stress and true anaphylactic events remains unestablished at this time and controversial.
Thank you again for your inquiry and we hope this response is helpful to you.
1. Webb L and Lieberman P. Anaphylaxis: A Review of 601 Cases. Annals of Allergy, Asthma, and Immunology, July 2006; 97(1):39-43.
Undifferentiated somatoform idiopathic anaphylaxis: Nonorganic symptoms mimicking idiopathic anaphylaxis
Journal of Allergy and Clinical Immunology
Volume 96, Issue 6, December 1995, Pages 893–900
Choy, et al.
Background: Northwestern University's Division of Allergy and Immunology has had experience with the diagnosis and treatment of more than 350 patients with idiopathic anaphylaxis (IA). In 1992 we reported a group of patients with IA whose presentations mimicked IA, but IA and other organic causes were later excluded. Psychologic factors were suspected as the underlying problem. These patients were classified as IA-variant. Management of these cases was extremely difficult. There was significant morbidity and high and unnecessary costs.
Objective: We aim to distinguish the nature of this disease and to highlight the evaluation and treatment of this group of patients.
Methods: Their cases are reviewed and reported.
Results: Common features included (1) presenting symptoms mimicking IA, (2) no objective findings that correlated with 1, (3) no response to the therapeutic regimen for IA, (4) meeting the Diagnostic and Statistical Manual of Mental Disorders criteria for undifferentiated somatoform disorder, and (5) significant wasted health care expenditure.
Conclusions: This group of patients were better defined as having undifferentiated somatoform-IA. An algorithm was proposed to expedite the diagnosis of the disease so that with early recognition of the disease, unwarranted repetitive consultations, tests, and inappropriate therapy can be avoided. (J ALLERGY CLIN IMMUNOL 1995;96:893-900).
Phil Lieberman, M.D.