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Introduction | Anaphylaxis | IA | Mast cells | Misconceptions

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Misconceptions: Frequently asked questions

What’s a “pseudo allergic reaction”?

[Cartoon of doctor saying: It says he died of a pseudo allergic reaction... Does that mean he's not really dead?] Original cartoon by Candace Van Auken.

Note: I don’t get this question from people who have idiopathic anaphylaxis (IA) — instead I have heard it from people who don’t know much about the disease. Somehow, they’ve gotten the idea that a “pseudo allergic reaction” is something like a false or fake or feigned reaction — or is at least much less serious than a supposedly “real” instance of anaphylaxis.

Answer: In reading articles about IA, you may see references to a “pseudo allergic reaction.” For example: Dr. Roy Patterson, 1997 [Patterson R, ed. Idiopathic anaphylaxis. Providence, RI: OceanSide Publications; 1997; xi.], wrote, “The terms anaphylactoid or pseudo allergic reactions have since been applied to differentiate them from IgE mediated reactions.”

It’s important to understand that the reaction is not what’s “false,” but rather the causative explanation. Allergists and other doctors assume that when someone has anaphylaxis, it is caused by a reaction that is mediated by immunoglobulin E (IgE). So what they mean by “pseudo” is that the attack is not IgE-mediated. The attack is just as systemic, just as life-threatening, and just as devastating, whether it is caused by an allergic or non-allergic mechanism. (And yes, if one succumbs to anaphylaxis that is not IgE-mediated, one can become just as “dead” as if the cause were a more typical allergy.)

Years ago, researchers and doctors called IgE-mediated attacks anaphylaxis and called non-IgE-mediated attacks anaphylactoid or pseudo allergic reactions, and there were a few (for example [Greenbaum J. Allergic rash: Does it exist? Can Fam Physician 1982;28:733–5) who felt that anaphylactoid reactions were inherently less dangerous than IgE-mediated reactions. However, at the current time, even though the term anaphylaxis is defined [Sampson HA, Muñoz-Furlong A, Campbell RL, Adkinson NF, Bock SA, Branum A, et al. Second symposium on the definition and management of anaphylaxis: Summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006; 117:391–7.] as “a serious allergic reaction that is rapid in onset and may cause death,” it is applied to anaphylaxis due to any cause, and anaphylaxis is regarded as a life-threatening emergency.

A variant on this misconception has been encountered by a few members of the IA Support group. For example, one IA patient was talking with a co-worker about the co-worker’s sister’s food allergies. The co-worker commented, “It's serious — she could have anaphylaxis and die!” The IA patient noted, “Well, so could I,” whereupon the co-worker objected, “Oh, no, I'm talking about real anaphylaxis, the kind that can kill a person.”

Just to be absolutely crystal clear on this point, let me say it again: Any attack of anaphylaxis, regardless of cause, has the potential to kill someone. People with IA have died from anaphylaxis.

For example, a recent newspaper article [“Mystery surrounds grandfathers death." The Express and Star Newspaper, Wolverhampton, West Midlands, UK. 15 September 2009.] from England, “Mystery surrounds grandfathers [sic] death,” reports the inquest into the death of a 74-year-old retired worker at a local pub. If he had died quietly at home instead of in a public place, surrounded by acquaintances, his death might have been written off to heart failure. However, an inquest was held and the local coroner determined that Mr. Brooks died of an anaphylactic reaction, “the precise cause of which was not established.”

Although the man had been eating nuts before he died, another doctor reported that tests for allergies to nuts were negative, although “a link could not be ruled out.” Also, the man’s daughter reported that he “had always eaten nuts.” It is altogether possible that what killed this gentleman was his very first attack of idiopathic anaphylaxis.

Can dust mites cause anaphylaxis?

Wikipedia photograph of a dust mite: Dermatophagoides pteronyssinus

Original question: “I'm allergic to dust mites, but my allergist said that dust mites don't cause anaphylaxis. Is this true?”

Answer: I wonder if your doctor is aware of the 2003 medical journal article[Edston E, van Hage-Hamsten M. Death in anaphylaxis in a man with house dust mite allergy. Int J Legal Med. 2003 Oct;117(5):299-301], which told of a “case, which initially appeared to be due to sudden death of unknown cause. A 47-year-old farmer was found dead in his bathroom around midnight. Hospital records revealed that he had previously been diagnosed with an allergy to house dust mites. He had also had infrequent episodes of airway symptoms, nausea, hypotension and diarrhoea usually after going to bed.” This man didn’t have idiopathic anaphylaxis (IA) or mastocytosis — just a dust mite allergy.

Of course, not all mites are created equal, as one group of researchers[Wen DC, Shyur SD, Ho CM, et al. Systemic anaphylaxis after the ingestion of pancake contaminated with the storage mite Blomia freemani. Ann Allergy Asthma Immunol. 2005;95:612–4] noted, “All mites can broadly be categorized as pyroglyphid [belonging to the family Pyroglyphidae] mites, referred to as house dust mites, or nonpyroglyphid mites, referred to as storage mites.” However, anaphylaxis has been caused by exposure to both kinds. That same case report[Wen DC, Shyur SD, Ho CM, et al. Systemic anaphylaxis after the ingestion of pancake contaminated with the storage mite Blomia freemani. Ann Allergy Asthma Immunol. 2005;95:612–4] notes that “sensitivity to storage mites is an occupational hazard in farming environments and for people living in damp houses.”

And then there was a victim of the “pancake syndrome,” (Hannaway PJ, Miller JD. The pancake syndrome (oral mite anaphylaxis) by ingestion and inhalation in a 52-year-old woman in the northeastern United States. Ann Allergy Asthma Immunol 2008 100(4):397–8] who had anaphylaxis after ingesting mites that had been packaged into her pancake mix. This patient had a history of dust mite allergy.

And by the way, "pancake syndrome," isn’t just for adults. There have been a number of studies that have documented the same reaction in children as young as seven, leading researchers[Sánchez-Borges-Borges M, Capriles-Hulett A, Caballero-Fonesca F. Oral mite anaphylaxis (pancake syndrome) also observed in children. Ann Allergy Asthma Immunol. 2006;96:755–6] to conclude:

…We emphasize that OMA [oral mite anaphylaxis] may occur in young allergic individuals, and pediatricians should be advised to consider this condition when a child presents with anaphylaxis of unknown origin that occurs after eating foods prepared with wheat flour, especially pancakes.

And according to Drs. Sampson and Burks[Sampson HA, Burks AW. Chapter 65: Adverse reactions to foods, in Adkinson NF, Busse WW, Bochner BS, Holgate ST, Simons FER, Lemanske RF, eds. Middleton's Allergy: Principles and Practice. 7th ed. Philadelphia: Mosby; 2009]:

Shellfish allergens [substances that cause allergic or hypersensitive responses] are considered a major cause of food allergic reactions in adults, affecting up to 2.3% of the US adult population. This group consists of a wide variety of mollusks (snails, mussels, oysters, scallops, clams, squid, and octopus) and crustacea (lobsters, crabs, prawns, crawfish, and shrimp). Shrimp allergens have been most extensively studied. Eighteen precipitating antigens [substances that can cause immune hypersensitivity reactions] have been detected by crossed-immunoelectrophoresis [CRIE]; seven appeared to be allergens as determined by CRIE using a pool of sera from six shrimp allergic subjects. Tropomyosin, a protein found both in muscle and elsewhere, has been identified as the major allergen in shrimp. Considerable cross-reactivity among crustacea has been demonstrated by skin test and radioallergosorbent test (RAST) analyses. Invertebrate tropomyosins are highly homologous and tend to be allergenic — those from crustaceans (e.g., shrimp, crab, crawfish, and lobster), arachnids (house dust mites), insects (cockroaches), and mollusks (squid, snails) — whereas vertebrate tropomyosin tends to be non-allergenic.

What this means is that someone who has an oral allergy to eating mollusks or crustacea may have a cross-reactivity to house mites.

Also, one of the three deaths from IA that Dr. Paul A. Greenberger[Greenberger PA. Idiopathic Anaphylaxis. Immunology and Allergy Clinics of North America 2007; 27:273-93] cites was that of a patient who had a dust mite allergy. Even if dust mite reactions were only rarely associated with anaphylaxis in the typical allergy patient, that does not preclude someone with IA from having a more severe reaction. Having severe reactions is what those of us who have IA do best!

If your allergist meant that dust mites are not frequently recognized to be the cause of anaphylaxis, then I’d be more inclined to agree with him, but given that studies have shown that anaphylaxis is under-diagnosed, if anything there are probably more cases of dust mite-induced anaphylaxis out there than most doctors realize.

Plus, my very first attack of anaphylaxis came on about 15 minutes after I’d laid down to go to sleep. Back then there was no such diagnosis as IA, and the allergists I later saw assured me that my anaphylaxis had been caused by — dust mites!

Was the first person to die of anaphylaxis an Egyptian pharoah?

Photograph of bust of King Menes, a Pharoah of ancient Egypt.

No. There are factoids that capture our imagination and are spread around by people who assume that they are correct. They are sometimes called “urban legends,” and this story seems to be an academic example thereof.

Even though a number of otherwise-reputable authors (References: Brown, 1995, p. 89 [Brown, A. F. Anaphylactic shock: mechanisms and treatment. J Accid Emerg Med. Jun 1995; 12(2):89–100]; Patterson, 1997, p. xi [Patterson R, editor. Idiopathic anaphylaxis. Providence, RI: OceanSide Publications; 1997]; Wassermann, 2000, p. 3 [Wassermann SI. The allergist in the new millennium. J Allergy Clin Immunol. 2000; 105:3–8]; Ring, 2010, p. 2 [Ring J, Behrendt H, de Weck A. History and classification of anaphylaxis. Chem Immunol & Allergy. 2010; 95:1–11]) credit King Menes, reputed to be the ancient Egyptian king who founded the First Dynasty, with being the first person in recorded history to have died of an insect sting, this is incorrect.

Why? Well, first of all, King Menes is a mythical figure. It is altogether possible that he did not exist.

Secondly, there is only one source for the idea that King Menes died from a wasp or hornet sting, and that source turns out to be a modern writer whose interpretations of hieroglyphics could be said to be of highly questionable accuracy. His findings have been accepted by no other Egyptologists. Reference [Krombach JW, Kampe S, Keller CA, Wright PM. Pharaoh Menes' death after an anaphylactic reaction—the end of a myth. Allergy. Nov 2004; 59(11):1234–1235].

Does “angioneurotic” mean only neurotics have angioedema?

Original question: “My brother came across an older name for angioedema [swelling in deeper layers of skin, mucus membranes or internal organs], ‘angioneurotic edema,’ and he decided that means that only neurotic people have angioedema. Is this true?”

Photograph of Sigmund Freud

Sigmund Freud, who had nothing whatsoever to do with naming angioedema.

Answer: Not at all! Your brother’s faux etymology is actually an anachronism. To wit (as they used to say, back in the days when they said “angioneurotic”), it was 1808 when Robert Willan penned the first description of angioedema. Years later, in 1882 when a German doctor, Heinrich I. Quincke, called it “angioneurotic edema,” he was simply using the parlance of his time in an attempt to describe the phenomenon. After his description, other doctors tended to call it Quincke’s edema, thus honoring the man who they thought had first described it. Reference [Simons FER. Ancestors of Allergy. New York, NY: Global Medical Communications Ltd.; 1994; 102].

Sigmund Freud, the man who later promoted concepts like that of neurosis, was just completing his basic medical education around the time that Quincke published his observations. He was years away from the work for which he would become famous. And Quincke knew nothing of the terminology Freud would later appropriate in developing his theories of personality. Perhaps your brother should use our Anaphylaxis Timeline to brush up on the pertinent medical history.

And in case anyone asks, Robert Willan, back in 1808, was describing the reaction that another physician, Dr. Thomas M. Winterbottom, had after consuming a small portion of sweet almonds. He identified a reaction to the food as the cause of the swelling — not some twisted aspect of the man’s psyche.

Is there a connection between multiple chemical sensitivity and IA?

Original question: “When I try to explain to someone what IA is, they sometimes assume that what I am describing is multiple chemical sensitivity (MCS). Is there a connection between IA and MCS — or are they different names for the same thing?”

Photograph of woman with MCS wearing an oxygen mask by Beth/live w mcs, taken January 23, 2009.

“Oxygen Mask” photograph by Beth/live w mcs, taken January 23, 2009.

Answer: Idiopathic environmental intolerance syndrome [also known as multiple chemical sensitivity, environmental illness, universal allergy, 20th-century disease, chemical hypersensitivity syndrome, total allergy syndrome, and cerebral allergy] is a completely different condition.

The biggest single difference is that in idiopathic anaphylaxis (IA), the person reacts to whatever they react to (or to nothing in particular) by having anaphylaxis [a life-threatening, systemic allergenic (or quasi-allergenic) reaction]. The symptoms are highly specific and fall within the range of symptoms one would expect from total mast cell degranulation. Even when a person with IA has partial mast cell degranulation on a frequent — or daily — basis, they experience the same kinds of symptoms, and not taking adequate amounts of the appropriate medications will lead to full-blown attacks of anaphylaxis.

In comparison, the symptoms of IEI/MCS are much more likely to be both less life-threatening and less specific. For example, headache, fatigue, dizziness, and cognitive dysfunction. Any of these symptoms may be observed in people with IA, but also in people with many other autoimmune and chronic diseases. Further, if someone with IA has, for example, dizziness, they are more likely to have that progress to faintness and/or loss of consciousness (due to plummeting blood pressure). Again, in IA, headache is often correlated with sinus involvement or to a related condition such as migraine.

Another difference is that a person who has idiopathic environmental intolerance (IEI) has symptoms in response to exposure to environmental chemicals, most often identified by odor. While there are cases of people with IA having anaphylaxis in reaction to chemical odors (for example [Saunders Jr RL, Halpern GM, Gershwin ME. Odor associated idiopathic anaphylaxis. A case report. Allergol et Immunopathol. 1995; 23(1):35–7]), there are far more cases where they react to natural substances, to elevated levels of any particulate matter in the air, or even to the time of day.

For me, personally, my attacks seem to be as likely to be set off by the smell of burning toast or a raw onion as by the smell of freshly laid asphalt or someone’s perfume. And like most people with IA, I can be set off by things that have no noticeable scent or odor.

One thing that IEI and IA share is that some members of the medical community question the validity of each of these diagnoses. Some doctors regard IEI/MCS as a psychosomatic disorder, that is, as a disorder that does not arise from an organic disease or condition. Reference [American Academy of Allergy, Asthma and Immunology (AAAAI) Board of Directors. Idiopathic environmental intolerances. J Allergy Clin Immunol. Position statement. 1999; 103:36–40]. Meanwhile, other doctors question the diagnosis of IA because they believe that it is a form of hidden allergy. Reference [Sheffer AL. Unraveling the mystery of idiopathic anaphylaxis. NEJM. 1984; 311(19):1248–1249].

My heart goes out to people with IEI/MCS because so many doctors (for example [Cohn JR. Multiple chemical sensitivity or multi-organ dysesthesia. J Allergy Clin Immunol 1994; 93:953-4]) prefer to view it as a contemporary form of hysteria and/or neurasthenia. The fact that it affects twice as many women as men insures that the traditional medical bias will be in the direction of trivializing the condition, but what dooms it, in research terms, is the lack of a unique constellation of symptoms and/or laboratory markers for the condition.


Page last updated: May 28, 2011

All information contained in this site is one layperson's interpretation of medical journal articles, textbooks, seminars, presentations, and other materials. Nothing that is stated here should carry more weight than the informed and considered opinions of your own highly trained and qualified medical caregivers. The author of this site is not a doctor and has absolutely no authority to prescribe or diagnose.

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