A 23 y/o female medical student, on vacation in Florida presents with a painful red rash. The rash is located in several different patterns. There is a rectangular pattern on her left thigh, and also 2 linear streaks on her right leg and mildly on her left leg. It initially was just red and painful, but progressed to very painful blisters. Pain was to the extent that she was unable to wear pants, as the pain was unbearable if anything touched her left thigh lesion. She also felt the lesions were possibly spreading as she noted a spot behind her left ear, on her forehead, and on her abdomen a day or two after the rash started. The rash was not pruritic. The rash on the thigh had a red area that was spreading beyond the initially involved rectangular area. No unusual bites or new exposures. No new soap, perfume or clothes.
There were no constitutional symptoms, no fever, vomiting, etc. She had traveled from Detroit, Michigan to West Palm Beach, Florida for winter break, and had spent some time the first few days on the beach doing yoga. She didn’t recall any bites from anything.
PMH, SH, FH were found unremarkable. Physical exam is normal except for skin findings.
See pictures below:
1. What key question did I not ask?
I never asked about limes. This patient had phytophotodermatitis (‘Phyto’ meaning plant, ‘Photo’ meaning light, and ‘dermatitis’ is inflammation of the skin). (1) This is a cutaneous inflammatory contact dermatitis, which results from ultraviolet exposure after contact with certain chemicals. One of these chemicals is found in limes. Limes contain furocoumarins, which are harmless, but when exposed to UV light, they become very irritating to the skin. It is often described as looking like paint dripping down the arm or leg. Some references refer to this as ‘Margarita dermatitis’. Blistering is a common finding in this type of painful contact dermatitis.
These chemicals are also found in fragrances, some fruits, and even some grasses. Additionally, other plants such as carrots, parsnips, dill, fennel, celery and anise have been known to cause this reaction (2), and even figs can cause this. (3, this reference has great pictures). Research has suggested that the interaction of sunlight and these chemicals generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. (4)
2. Is this condition very commonly associated with cellulitis?
Overall, more than 10% of patients labeled as having cellulitis do not have cellulitis. (5). Misdiagnosis can result in over use of antibiotics, with the consequent complications. The most common mimic of cellulitis is stasis dermatitis. Patients with stasis dermatitis present with ill-defined, bilateral, pitting edema with erythema, hyperpigmentation, and sometimes superficial desquamation. In stasis dermatitis, the underlying problem is chronic venous insufficiency, which results in interstitial edema, extravasation of red blood cells, and ultimately the appearance of cellulitis. (5) Although a secondary cellulitis of a contact dermatitis can occur, it is not very common. (5) It was likely overkill to prescribe Keflex.
3. How can it be easily prevented?
Prevention of phytophotodermatitis is from 3 techniques: do not contact limes (or other sources of this reaction) if you are sensitive to this condition, if you do contact them, rinse skin thoroughly before sun exposure, or stay in side and avoid sunlight, or wear sunblock (at least SPF 30).
4. Are there any long lasting effects?
After healing, the skin will often remain hyper pigmented. This post inflammatory hyperpigmentation can last for months. (6) Although hyperpigmentation is common, actual scaring is not. (6).
The pattern clearly suggested a contact dermatitis. However, even after a lengthy conversation about anything new, no obvious contact source was found. Initially I thought the increasing redness around the rectangle patch could be a secondary cellulitis and started treatment with Keflex. I also started topical steroids. The next day when I examined her, it was not getting any better and blistering continued (although patient had not started topical steroids). I called a friend of mine (an excellent Dermatologist) who then asked about limes. When I queried the patient, she looked astonished and explained that she had been cutting up limes every day to put in her drinks while near the beach, flavor other foods, and had consumed more than 1 lime a day. The patient had even been taking lime wedges down to the pool to flavor her drinks, which provided a likely time for the exposure to lime juice and UV-sunlight. The linear streak marks on the right thigh are characteristic of phytophotodermatitis, likely due to fingers transferring the juice to the skin. So, now the diagnosis was made, we started the topical steroids and a 3-day course of oral steroids (the patient had to start her med school classes in 3 days and was very concerned about wearing pants over her skin lesion as it was so painful). The dermatologist also suggested dilute white vinegar (mix 1 cup cold water with 1 table spoon white vinegar) and place on rash for 15 min, repeating 4 times a day. Patient was prescribed Clobetasol Propionate cream (0.05%) to apply topically 4 times per day. Over the next 2-3 days, substantial improvement occurred. Pigmentation changes remain, but are improving.
This case of phytophotodermatitis involved only a small surface area of the body. In some cases, when the surface area involved is larger, patients may need to be transferred to a burn center. Additionally, Phytophotodermatitis in small children can sometimes be misinterpreted as physical abuse due to the appearance of hand marks or finger prints that result from the transfer of the fruit juice onto the skin.
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1. Sarhane KA, Ibrahim A, Fagan SP, Goverman J. Phytophotodermatitis. J Plastic Surgery, eplasty 2013;13;ic57. Accessed at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3772689/
2. Goon ATJ and Goh CL. Plant Dermatitis: Asiann perspective. Indd Jour Deerm 2011 Nov-Dec;56(6):707-710. Accessed at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276901/
3. Moreira AID, Leite I, Guedes R, Baptista A, Ferreira EO. Phytophotodermatitis ñ An occupational and recreational skin disease. Rev Assoc Med Bras 2010 May-Jun;56(3):269-70. Accessed at: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-42302010000300008&lng=en&nrm=iso&tlng=en
4. Almeida HL Jr, Sotto MN, Castro LA, and Rocha NM> Transmission electron microscopy of the preclinical phase of experimental phytophotodermatis. Clinics (Sao Paulo) 2008 Jun;63(3):371-4. Accessed at: http://www.ncbi.nlm.nih.gov/pubmed/18568248
5. Keller EC, Tomecki KJ, Alraies MC. Distinguishing cellulitis from its mimics. Cleve Clin Med 2012 Aug;79(8):547-52. Accesssed at: http://www.ccjm.org/content/79/8/547.long
6. Baugh WP, Elston D. Phytophotodermatitis. Medscape, Jan 25, 2012. Accessed at: http://emedicine.medscape.com/article/1119566-overview