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by Louis P. Theriot, M.D., F.A.A.P.
May 16, 2005
It was an early Sunday morning when I was making teaching rounds with the pediatric residents. Having just finished a 24-hour on call stint, they were a beleaguered bunch. It had been a particularly busy call for them, having had a large number of admissions and sick children to deal with. As we made our way down the list of admissions I could sense that the adrenalin in their bloodstream was waning a bit. Some of the medical students had that glossed-over look in their eyes. It would be dishonest to say that on more than one occasion I noticed a couple of the house staff doing the proverbial airplanes.
We were down to the last admission they needed to present so that we could discuss the case. I saved this one for last because he is very interesting--a real puzzle that has everyone stumped, said the senior resident nodding to the intern to present the history. Billy, an 11-year-old male, is in relatively good health. He has some allergies, attention deficit syndrome, and large tonsils and adenoids causing occasional snoring and possibly sleep apnea at night. He was not an obese individual, but actually looked quite fit.
Apparently the day before coming to our hospital Billys mom noticed that he had a bluish/grayish hue to his face and hands. She became worried even though he said he felt fine. As this did not seem normal she took him to a local community hospital. They, too, were impressed with the bluish color of his hands and face.
This sent up red flags for urgent conditions such as carbon monoxide poisoning. The emergency room sent off stat labs that included a carboxyhemoglobin and methemaglobin. Both were normal as well as the usual labs of CBC and chemistry panel. They also did an arterial blood gas to see if his oxygen concentration was low. This, too, was textbook perfect. Then EKG and chest x-rays were performed and both were normal. Because of the history of large adenoids, a CT scan of his neck was taken and the result was normal as well. Given all of these normal values in a boy with blue face and hands he was transferred to our intensive care unit for further evaluation.
He was certainly in no distress upon arrival to the ICU. Having had such a thorough work-up at the outside hospital it seemed unwarranted to repeat all the labs that were known to be normal. They did repeat the blood gas. Once again it was normal in all respects. He was then transferred to our service. After the interns lengthy presentation several of the weary interns and medical students were hanging on by just a thread. You could sense them thinking, If I could just put my head down on this table for two seconds...
Following the presentation of the history with all the normal labs and studies obtained, I could think of NO medical condition that would cause this. Distribution of the discoloration was most interesting. It was as if Bill had handled something with his hands, transferring it to his face. Then it came to me. I remembered dealing with a few similar cases over the years. I asked the intern if Bill had handled lemons lately. She looked at me with incredulous disbelief, blinked her eyes, and paused to think. Had she really heard me ask that, or had she fallen asleep and this was all a bad dream? I continued, You know, had he made lemonade or something recently? The intern shrugged to the senior resident as if to say, I give up! YOU take this one. By now the whole team seemed to wake up and shuffled in their seats. Since this was our last new patient to discuss I suggested that we proceed now and see all of the patients.
We wanted to see Billy first since he was such a puzzle. Making our way down to his room I was shown his chest x-ray and EKG. They were very normal. As we walked in the room Bill was sitting up in bed, cross-legged, playing a video game intently. Our team approached the bed and I introduced myself explaining that we were making rounds.
Billy was a healthy looking boy with a grayish hue to his forehead, cheeks and hands. But he was in no distress whatsoever. In fact, he was so focused on his game he stuck out his hand to shake mine without taking eyes off the screen. I asked, Bill, have you handled any lemons lately? Without a pause or looking away from the screen he stated, Yeah, on Thursday. I was able to find out that Bills family has a large lemon tree in the yard full of fruit. On Thursday, two days before he came to the ER, he and friends spent a good part of the afternoon throwing lemons at each other, pitching them to be hit with a bat. Then they spent a considerable amount of time picking up the pieces of rind since mom was none too happy about their little venture. Sure enough, Bill had a condition called phytophotodermatitis.
Phytophotodermatitis (PPD) refers to a phototoxic reaction consisting of erythema, or redness of the skin, and, in some cases, blistering of the skin. This is followed by a delayed hyperpigmentation. This is NOT an immunologic reaction. Therefore, it can occur in virtually anyone and no prior sensitization is required. The chemical agents responsible for PPD are the Furocoumarins that are believed to be related to a plants natural defenses against fungal attacks. There are two major types of these chemicals: a linear form (psoralen) and an angular form (angelical). It is the psoralen group that is most associated with PPD. These chemicals are found in a wide variety of plants. The more common ones include Bishops weed, cow parsnip, celery, limes, figs, gas plants and Bergamot limes.
When these chemicals get onto the skin and are exposed to natural sunlight a series of reactions take place. First dermatitis is caused, then a delayed melanogenesis whereby the number of melanocytes, or cells which produce pigment, may increase threefold. This results in hyperpigmentation that is seen with PPD. There have been extensive studies and it is know that the spectrum of sunlight reaching the Earth ranges from 270-5000 nm. It is in the 320-380 nm range where most of the PPD occurs.
This phenomena has been recorded in ancient literature from Egypt as far back as 2000 B.C. It was used to treat vitiligo, a skin condition resulting in patches of skin that have no pigment, thereby leaving white patchy areas. Patients were instructed to rub leaves from Bishops weed that grew wild on the banks of the Nile onto the areas of vitiligo. Then they were to lie in the sun. In Europe this condition was referred to as Berlocks dermatitis. It comes from the French word breloque that means charm or trinket to describe the pendant-shaped lesions found on the face, hands and neck.
Certain activities that may increase ones risk of developing PPD are: cultivating celery, parsley or parsnips; pruning figs; making lemonade or handling limes (the majority of the psoralens are in the rind, not the pulp); clearing certain weeds with a weed-whacker which can lead to a buckshot spray of hyperpigmented areas; wearing a lei that contains the flower mokahina, which is grown on Kauai.
PPD is a self-limited and self-resolving condition rarely requiring any treatment. In the early phase of dermatitis, if there is significant itching or blistering, one could use a topical steroid for symptomatic relief. Some authors suggest that the steroids may actually modify the extent of the hyperpigmentation that occurs. It has also been suggested that nonsteroidal-anti-inflammatories may be helpful in the treatment of the symptoms. Regardless, PPD will resolve completely in time.
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