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Journal of the American Academy of Physician Assistants:
doi: 10.1097/01.JAA.0000442705.41341.3a
Dermatology Digest

What is this streaky rash?

Shah, Naura PA-C; Khachemoune, Amor MD, FAAD, FACMS

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Naura Shah practices at Premier Dermatology in Ashburn, Va. Amor Khachemoune is program director of the procedural dermatology fellowship at SUNY Downstate, N.Y., a dermatopathologist and Mohs Micrographic Surgeon at Premier Dermatology, and on the dermatology service at the Veterans Affairs Medical Center and SUNY Downstate. The authors have disclosed no potential conflicts of interest, financial or otherwise.

Michael D. Overcash, MPAS, PA-C, department editor

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CASE

A 38-year-old woman was seen in our clinic 1 week after traveling to Hilton Head, S.C., for a wedding. The patient complained of an initial burning sensation on her legs followed by mild blistering on the second night during her stay. The acute symptoms prompted her to go to a local urgent care facility where she received supportive care. After the acute symptoms subsided within 24 hours, she reported a nonpruritic brownish discoloration on her legs, which prompted her current visit. A physical examination demonstrated well-demarcated hyperpigmented linear streaks on the anterior aspect of the bilateral lower legs (Figure 1). The patient initially did not recall any contributing factors that could have caused the reaction.

Figure 1
Figure 1
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THE MOST LIKELY DIAGNOSIS IS

* porphyria cutanea tarda

* allergic contact dermatitis

* phytophotodermatitis

* fixed drug eruption.

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DISCUSSION

The correct diagnosis is phytophotodermatitis, a nonimmunologic phototoxic reaction caused when skin contacts plants that contain psoralen and is then exposed to UV light. These compounds are at their highest concentrations during the spring and summer, which increases the likelihood of exposure.1,2 Common inducers of this sun-related dermatologic reaction include celery, wild parsnip, parsley, lemons, and limes. Although phytophotodermatitis can occur worldwide, it typically occurs in individuals who go outdoors near wildlife and wooded areas that contain the offending plants. People who work in professions that directly handle citrus plants are at increased risk. The overall incidence in the United States is unknown, and any ethnicity can be affected.3,4 The sap of fig trees (Ficus carica) and seeds of Psoralea corylifolia also can induce phytophotodermatitis.3 A distinguishing feature is that phytophotodermatitis only appears on body areas that have had direct contact with the offending agent's chemicals and direct sun exposure.

Also known as “margarita dermatitis” or “lime dermatitis,” phytophotodermatitis is most likely to be seen in bartenders, chefs, and people who regularly handle citrus fruits. A “dripping” pattern may be seen in patients who present with phytophotodermatitis—wherever the citrus juices have dripped onto the skin and have had subsequent sun exposure, distinct cutaneous skin eruptions can result.

The clinical presentation may vary, but patients may present with a burning sensation as well as bizarre and linear erythematous vesicular plaques on affected areas; these symptoms typically develop within 12 to 36 hours.5 The most commonly affected areas are the dorsa of the hands, wrists, forearms, and lower legs. As the lesions heal, postinflammatory hyperpigmentation can follow, which may take months to resolve.6 Pruritus is not a common manifestation, per case reports.

After further questioning, additional history was obtained from the patient. She recalled that she had spilled a margarita on herself during the prewedding celebrations, hence confirming our clinical diagnosis.

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DIFFERENTIAL DIAGNOSIS

Porphyria cutanea tarda is characterized by vesicles and bullae rather than being an acute reaction to UV light such as phytophotodermatitis; cutaneous skin eruptions occur due to minor skin trauma and repetitive sun exposure. This condition may be genetic or acquired and specifically involves decreased uroporphyrinogen decarboxylase, an enzyme involved with heme synthesis.7,8 Although blisters are the most common manifestation, they are not specific to the condition. Hyperpigmentation may occur in diffuse patterns, compared with the bizarre linear streaking seen in phytophotodermatitis.

Allergic contact dermatitis can present in a similar fashion to phytophotodermatitis, with erythema, papules, and vesicles. Allergic contact dermatitis is distinguished by being confined to the site of exposure of an allergen; acute cases usually present in a linear distribution and are associated with intense pruritus and may include features such as erythema, vesicles, and bullae.9 To avoid misdiagnosis, take a full medical history and ask patients when and how the skin reaction occurred, then conduct a thorough skin examination.

Fixed drug eruptions tend to present as well-defined and ovoid violaceous plaques that may have associated pruritus, pain, or burning sensations as well as being confined to the same sites each time the offending agent is administered.10 Postinflammatory hyperpigmentation can follow, such as in phytophotodermatitis, but patients with fixed drug eruptions will not have a bizarre streaking pattern as in phytophotodermatitis.

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PREVENTION AND TREATMENT

Providers must reassure patients with phytophotodermatitis that symptoms will resolve on their own. Advise patients to wash their hands and any skin that comes into contact with psoralen-containing plants. After the acute eruption, suggested skin care includes topical anesthetics and first-aid creams, if needed, as well as washing the affected areas with mild soap and water, applying cool compresses, and wearing sunscreen when outside. Finally, provide patient education about residual hyperpigmentation management. Hyperpigmentation associated with phytophotodermatitis will typically resolve on its own within several weeks to months. However, patients should minimize exposure to sunlight and photosensitizing agents after the initial acute reaction.11

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REFERENCES

1. Cather JC, Macknet MR, Menter MA. Hyperpigmented macules and streaks. Proc (Bayl Univ Med Cent). 2000;13(4):405–406.

2. Stoner JG, Rasmussen JE. Plant dermatitis. J Am Acad Dermatol. 1983;9(1):1–15.

3. Derraik JG, Rademaker M. Phytophotodermatitis caused by contact with a fig tree (Ficus carica). N Z Med J. 2007;120(1261):U2720.

4. Kung AC, Stephens MB, Darling T. Phytophotodermatitis: bulla formation and hyperpigmentation during spring break. Mil Med. 2009;174(6):657–661.

5. Goskowicz MO, Friedlander SF, Eichenfield LF. Endemic “lime” disease: phytophotodermatitis in San Diego County. Pediatrics. 1994;93(5):828–830.

6. Webb JM, Brooke P. Blistering of the hands and forearms. Phytophotodermatitis. Arch Dermatol. 1995;131(7):834–835, 857–858.

7. Vieira FM, Nakhle MC, Abrantes-Lomes CP, et al. Precipitating factors of porphyria cutanea tarda in Brazil with emphasis on hemachromatosis gene (HFE) mutations. Study of 60 patients. An Bras Dermatol. 2013;88(4):530–540.

8. Sassa S. Modern diagnosis and management of the porphyrias. Br J Haematol. 2006;135(3):281–292.

9. Usatine RP, Riojas M. Diagnosis and management of contact dermatitis. Am Fam Physician. 2010;82(3):249–255.

10. Breathnach SM. Drug reactions. In: Burns T, Breathnach S, Cox N, Griffiths C, eds. Rook's Textbook of Dermatology. 8th ed. Oxford: Blackwell Science; 2010:28–177.

11. Rademaker M, Derraik JG. Phytophotodermatitis caused by Ficus pumila. Contact Dermatitis. 2012;67(1):53–56.

© 2014 American Academy of Physician Assistants.

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