- As my co-authors and I say in our book, "Asthma Allergies Children: A Parent's Guide," a good history solves the mystery. Those who have read it are familiar with our unbounded admiration for the work of Sir Arthur Conan Doyle, creator of Sherlock Holmes, who was "A Dr. before he was a Sir." Holmes' keen eye for evidence was inspired by Doyle's med school instructor, Dr. Joseph Bell
. Most allergists are firmly in that dogged tradition of inquiry to find evidence that will lead to better outcomes. Allergies are tricky. Associating cause and effect is often difficult. I take a great deal of effort to track the triggers to an allergic reaction because it is right for the patient; you stand a chance of avoiding repetition. You might say, those who don't know history are doomed to repeat it. It also makes the practice of this specialty interesting, year in and year out.
I have had many Dr. Joseph Bells in my career, doctors who taught me to think below the surface of a problem, not just treat the symptoms. Readers of Hamptons.com will appreciate this story, which concerns two of them.
My father, known to generations of Long Island children as Dr. Lennie
, once pulled a drowning man out of the Amagansett surf in the 1960s. As the man regained his strength, he looked at my father's face and said, "I assume you're not using makeup, so I must advise you not to use that suntan lotion." It was Dr. Alex Fisher
, author of the deﬁnitive text on contact dermatitis. He gave my father an autographed copy of his book. Dr. Fisher had noticed a bumpy rash on my father's face. It is simple to assume that such a rash is due to a contactant, i.e., an allergen exposed by contact, but many times one needs to be a sleuth to discover which one. Dr. Fisher assumed correctly that Dr. Lennie was not using makeup, and so he concluded, correctly so, that his suntan lotion must be the problem.
That book - "Contact Dermatitis" - has been an indispensable resource and inspiration for me throughout my career.
Sometimes it's not so simple. Thus it was when a new patient came to my office last fall, complaining of a "strange body-wide rash." With dermatitis, patients may choose to go to a general practitioner or a dermatologist, who may give them prednisone, which will take care of the symptoms. But allergists generally try to solve the mystery. People can get "contact dermatitis" from things as disparate as nickel in jewelry to make-up. Other rashes can come from things like food. With something as widespread as this rash, I thought it unlikely the cause was jewelry or make-up, which results in local reactions and can be treated with topical medications.
We went back day-by-day to the beginning of the outbreak trying to figure out where she had been, what she had eaten, and what she had touched. It turns out that she is a volunteer at the world famous Brooklyn Botanic Garden, and she had attended a dinner there at which each guest was given a plant. She had, in fact, scratched herself on it. I gave her prednisone, which did its work, and on a follow-up visit she brought along the offending plant. Unsurprisingly, she left it with me. I subsequently received the following reply to an inquiry she had made to the president of the Botanic Garden, who passed it along to one of the scientists:
From Dr. Kerry Barringer, curator of the herbarium at Brooklyn Botanic Garden:
It turns out that the sap in the leaves of many Agave species can cause a nasty dermatitis in some people. I can't find any specific reports for Agave attenuata, but many other species are known sources.
The culprit seems to be calcium oxalate crystals in the sap. These needle-like crystals can pierce the skin and act as irritants. The rash can blister and usually lasts for one to two weeks. Some people report recurrent itching for up to a year after exposure. Calcium oxalate crystals occur in many monocots and are known to cause dermatitis in people handling plants as diverse as Philodendrons and tulip bulbs.
There are also waxes, oils, and soap-like compounds that have also been tagged as potential allergens. Sometimes these can occur on the leaf surface and cause a reaction if someone gets scratched or poked by a spine.
With most plant allergies, sensitivity varies greatly among individuals. As you know, Agave attenuata is widely grown and is not generally considered to be problem, but everyone reacts differently.
A general reference on Irritant contact dermatitis, www.medscape.com/viewarticle/706404_5
An article on contact dermatitis from Agave americana, www.ncbi.nlm.nih.gov/pubmed/11109152
Dr. Kelly, MD is a facial plastic surgeon certified by the American Board of Facial Plastic and Reconstructive Surgery. Dr. Kelley currently practices with ENT Allergy Associates. www.peconic-faces.com