What’s Your Diagnosis?®

A Hyperpigmented Right Forearm Alexander K.C. Leung, MD, and Benjamin Barankin, MD

History An 18-year-old female returned from Mexico and was con- cerned about the on her right forearm. Two weeks earlier, juice was accidentally squirted on her forearm during a barbecue on a sunny beach in the Bahamas. By the following morning, a burning sensation and were noted in the affected forearm. Ten days later, the ery- thematous area became hyperpigmented.

PHYSICAL EXAMINATION Physical examination revealed 2 well-demarcated hyperpig- mented patches on the flexor aspect of the right forearm and the medial aspect of the right elbow, respectively.

What’s Your Diagnosis? A. Irritant contact B. Polymorphous light eruption C. Porphyria cutanea tarda D. Bullous pemphigoid E. Phytophotodermatitis

people are outdoor more often with are commonly implicated.4 The most Answer: less protective clothing, and when ul- common plant families high in furocou- Phytophotodermatitis traviolet exposure is greatest.3,4 Perspi- marin content and capable of provoking ration, high humidity, and heat increase phototoxic reactions are (eg, Phytophotodermatitis refers to a non- the absorption of furocoumarins, limes, lemons, oranges, tangerines), fol- immunologic photosensitive dermal re- thereby increasing the intensity of pho- lowed by Umbelliferae (eg, , action induced by the contact to or, totoxic reactions. Phytophotodermatitis , , carrot), Moraceae (eg, very rarely, oral intake of a photosensi- is observed more frequently in indi- figs), and Leguminosae (eg, legume, pea, tive substance found in certain plants viduals who spend a lot of time par- bean).3-5 The wavelengths of followed by exposure to sunlight.1 Rob- ticipating in outdoor activities.4 There light that most effectively produce phy- ert Klaber in 1942 coined the term is no predilection for race, sex, or age, tophotodermatitis lie within the ultravi- phytophotodermatitis to describe the but the condition is most easily recog- olet-A 320 nm to 400 nm range, and phenomenon.2 Some people have since nized in fair-skinned individuals.3 have peak activity at 335 nm.4 referred to it as “Club Med” dermatitis. After the furocoumarins are exposed Etiopathogenesis to ultraviolet radiation, they form pho- Epidemiology Phytophotodermatitis results from the totoxic compounds that cause direct The exact incidence is not known as interaction of solar radiation and photo- damage to the DNA of epidermal cells. information on this condition is limit- sensitizing compounds in various plants. Two types of phototoxic reactions are ed to case reports. Phytophotodermati- Furocoumarins—such as , recognized. Type 1 is oxygen indepen- tis is most commonly seen in the sum- 5-methoxypsoralens (), 8-me- dent, in which the ultraviolet-activated mer when furocoumarins are at the thoxypsoralens (xanthotoxin), angelicin, furocoumarins bind to RNA and nu- highest concentrations in plants, when pimpinellin, limettin, and bergaptol— clear DNA.6,7 This results in interstrand

www.consultant360.com • July 2014 • consultant 557 What’s Your Diagnosis?® cross-linking with inhibition of DNA Diagnosis treatment. Cool compresses and topical synthesis. Type 2 is oxygen-dependent, The diagnosis is a clinical one. Key el- corticosteroids may be used to reduce where ultraviolet-activated furocouma- ements are taking a history of exposure local . NSAIDs can be used rins cause damage to epidermal, dermal, to a plant followed by sunlight exposure for pain relief. More severe cases may re- and endothelial cell membrane in addi- and familiarity in recognizing the clini- quire meticulous burn wound care. tion to intracellular enzymes, RNA, cal appearance of the lesion (typically No treatment is necessary for the and DNA.6-8 These reactions lead to linear). A skin biopsy should be consid- subsequent hyperpigmentation as it usu- apoptosis of keratinocytes, which mani- ered if the diagnosis is in doubt. ally fades over time. The use of over the fest clinically as erythema, , and Photopatch testing is not recom- counter topical 4% hydroquinone or a bulla formation.8 Subsequent hyperpig- mended because a positive response can prescription modified Kligman’s formu- mentation is caused by type 1 reaction be very severe.9 Referral to a dermatolo- lation will hasten resolution of the hy- and results from increased melanocyte gist should be considered if there is diag- perpigmentation. n mitosis and dendricity, melanocyte hy- nostic uncertainty. pertrophy, increased tyrosinase activity, Alexander K.C. Leung, MD, is a increase in number of melanosomes in Differential Diagnosis clinical professor of pediatrics at the Univer- melanocytes, and migration of melano- Differential diagnoses include irritant sity of Calgary and pediatric consultant at cytes from the epidermis to the der- , allergic contact der- the Alberta Children’s Hospital in Calgary, mis.3,6-8 Less commonly, hypopigmenta- matitis, polymorphous light eruption, Alberta, Canada. tion may result and is attributable to , chemical or thermal burn, apoptosis of melanocytes.7 herpes simplex, herpes zoster, child Benjamin Barankin, MD, is the medi- abuse, factitious dermatitis, atopic der- cal director and founder of the Toronto Derma- matitis, porphyria cutanea tarda, and Histopathology tology Centre in Toronto, Ontario, Canada. Histopathologic examination of a bullous pemphigoid.5,10 classic lesion in the acute stage shows References: spongiosis, vacuolization, and keratino- Complications 1.  Ozkol HU, Akdeniz N, Ozkol H, et al. Devel- cyte necrosis.4 Later on, intra- and sub- Rarely, the hyperpigmentation may opment of phytophotodermatitis in two epidermal blistering may be seen. be permanent and scarring may occur. cases related to Plantago lanceolata. Cut Ocu Toxicol. 2012;31(1):58-60. Clinical Manifestations Prognosis 2.  Klaber R. Phytophotodermatitis. Br J Der- matol. 1942;54:193-211. A phototoxic inflammatory eruption The prognosis is good. The hyperpig- 3.  Kung AC, Stephens MB, Darling T. Phyto- typically occurs 24 hours after the ex- mentation or usually : bulla formation and hyper- posure of the skin to a furocoumarin lasts for several months to a year. Reso- pigmentation during spring break. Mil Med. and sunlight, with a peak at 30 to 120 lution of the hyperpigmentation can be 2009;174(6):657-661. minutes.1,6 Clinically, this is manifested hastened with proper sun protection 4.  Zhang R, Zhu W. Phytophotodermatitis due to Chinese herbal medicine decoction. Indi- 7 as bizarre configurations of erythema and bleaching creams. an J Dermatol. 2011;56(3):329-331. with a sharply demarcated border con- 5.  Abali AE, Aka M, Aydogan C, Haberal M. fined to the area that has come in con- Prevention Burns or phytophotodermatitis, abuse or ne- tact with the offending plant agent and If contact with relevant plant or glect: confusing aspects of skin lesions consequent sun exposure. A burning known photosensitive compounds is caused by the superstitious use of fig leaves. J Burn Care Res. 2012;33(6):e309-e312. sensation and pain are prominent. Vesi- suspected, the exposed skin should be 6.  Rademaker M, Derraik JGB. Phytophotoder- cles and bullae may develop after 24 thoroughly washed with water and a matitis caused by pumila. Contact hours and peak at 72 hours, and often mild soap. Usually, there is a time lapse Dermatitis. 2012;67(1):47-57. accompanied by subsequent desquama- of approximately 30 to 120 minutes for 7.  Sarhane KA, Ibrahim A, Fagan SP, Gover- tion and denudation.6 Pruritus does not the furocoumarins to be absorbed into man J. Phytophotodermatitis. Eplasty. 2013; 13:ic57. 10 seem to be common. the skin. To avoid further exposure to 8.  Wagner AM, Wu JJ, Hansen RC, et al. Bul- Hyperpigmentation often develops sunlight, the affected skin should be lous phytophotodermatitis associated with 1 to 2 weeks later and can appear in covered for the next 48 to 72 hours. high natural concentrations of furocouma- bizarre streaks or drop-like patterns Regular use of broad-spectrum sun- rins in limes. Am J Contact Dermatitis. where the furocoumarin contacts the screens may help to prevent or diminish 2002;13(1):10-14. 9.  Zhang RZ, Zhu WY. Phytophotodermatitis 6 sun-exposed skin. Less commonly, the cutaneous effects of phytophotoder- due to wild carrot decoction. Indian J Der- hypopigmentation may result.4 Phy- matitis. matol Venereol Leprol. 2011;77(6):731. tophotodermatitis is most commonly 10. Carlsen K, Weismann K. Phytophotodermati- seen on uncovered sites exposed Management tis in 19 children admitted to hospital and to sunlight and plants such as arms In the acute stage, treatment is mainly their differential diagnoses: child abuse and herpes simplex virus infection. J Am Acad and legs. symptomatic. Mild cases may not require Dermatol. 2007;57(5 suppl):S88-S91.

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