Phytophotodermatitis

Phytophotodermatitis

Jonathan L. Held

Phytophotodermatitis Phytophotodermatitis is a skin eruption resulting from the interaction of the sun’s radiant energy and photosensitizing compounds found in various plants. Common offenders are celery, limes and certain oranges, as well as natural grasses. The acute phase of the skin eruption is characterized by edema and erythema. In the chronic phase, hyperpigmentation may develop at the contact site. Contact with plants and plant extracts containing photosensitizing compounds may result in a phototoxic dermatitis when the contact is followed by exposure to the ultraviolet rays of the sun. In the United States, phytophotodermatitis most often follows exposure to plants belonging to the Compositae, Umbelliferae and Rutaceae families.(1) These and other plants contain furocoumarins, which are photoactive compounds.

Examples of furocoumarin-containing fruits and vegetables include limes, lemons, celery and parsley. Because of frequent exposure to these items, grocery workers have been known to develop photodermatitis.(2,3) Phytophotodermatitis has also been reported in individuals who sunbathed in fields of grasses that contain furocoumarins.(4)

As in all forms of contact dermatitis, the acute skin changes of phytophotodermatitis are erythema and blistering, with the distribution of lesions reflecting the pattern of contact. The eruption appears about 48 hours after exposure. The major chronic manifestation of phytophotodermatitis is hyperpigmentation.

Berloque (locket) dermatitis, also called perfume dermatitis, is a variant of phytophotodermatitis. This cutaneous eruption, which usually consists of erythema and marked hyperpigmentation, develops in individuals who have applied fragrances containing oil of bergamot to their skin prior to sun exposure.(5) (Oil of bergamot is a fragrance essence derived from the rind of the bergamot orange.) Often the eruption initially appears as brown hyperpigmentation, without the preceding acute phase of inflammatory erythema. In such cases, localization of the hyperpigmentation to the neck or other sites of perfume application is frequently the only clue to the correct diagnosis.

This article presents a case in which a berloque type of eruption occurred as a result of a phototoxic reaction with another citrus fruit derivative. In this case, the distribution of the eruption misled both the patient and the clinician.

Illustrative Case

While vacationing in Mexico, a 23-year-old woman noticed an insect bite on her leg. The following day, because of pruritus and tenderness at the site of the bite, she applied a local remedy consisting of freshly squeezed lime juice. When she returned to the United States two days later, she noticed asymptomatic brown streaks arising in an annular pattern around the site of the insect bite and extending down her leg.

She was seen by her physician, who referred her to a dermatology clinic for evaluation of an arthropod bite reaction. The letter of referral specifically questioned whether the eruption could be an atypical presentation of Lyme disease (erythema chronica migrans).

CASE DISCUSSION

The situation in the illustrative case emphasizes the importance of obtaining a complete history of topical treatment when evaluating a skin eruption. The history of contact with lime juice, combined with the characteristic morphology of hyperpigmented streaks in the distribution of exposure to the offending photosensitizer, should have enabled the physician to make the proper diagnosis of phytophotodermatitis.

The referring physician in this case suspected Lyme disease because of the recent arthropod bite and some suggestion of annularity to the pigmentation. Actually, the hyperpigmented, streaky eruption was quite different from the red, round, ring-like patch or plaque with central clearing and peripheral expansion that is characteristic of classic Lyme disease. (The latter is a tick- or deerfly-borne spirochetosis unrelated to plant or solar exposure per se.) Ironically, the proper diagnosis in this case could be called “lime disease.”

Similar eruptions have occurred in travelers to various Club Med resorts, where a game is played that involves pushing limes over the skin of scantily clad sunbathers.(6) A characteristic feature of citrus fruit photodermatitis is the streaky, linear distribution caused by the dripping juice.

Mechanisms

Exposure to a furocoumarin-containing substance does not cause a skin eruption in the absence of exposure to ultraviolet light. Furthermore, phototoxic dermatitis is not an allergic phenomenon. On exposure to appropriate radiant energy, a photochemical reaction occurs that is independent of the host’s immunologic status. This process is distinct from photoallergic reactions such as drug-related photosensitivity syndromes, which require previous sensitization and an anamnestic response on reexposure to the offending antigens.(7)

It should be kept in mind, however, that certain systemic medications, such as sulfonamides and phenothiazines, may cause both phototoxic and photoallergic reactions. When phototoxicity results from systemic medications, the skin usually erupts in a sunburn-like erythema, but the striking hyperpigmentation demonstrated by the patient in the illustrative case usually does not occur.

Since nonimmunologic mechanisms are responsible for phototoxic dermatitis, almost everyone exposed to the offending agents might be expected to show a reaction on exposure to sunlight. However, there appears to be great variability in individual susceptibility to photodermatitis. Much of this variability can be explained by individual differences in stratum corneum thickness, number of hair follicles,(8) and amount and location of melanin in the skin.(9) The ability of the photosensitizer to be absorbed percutaneously is also an important variable and depends greatly on the vehicle in which the photosensitizer is applied.(10)

The exact mechanisms of phototoxic dermatitis vary with the offending agent and are still being studied. Currently accepted mechanisms have been reviewed by Harber and Bickers.(8)

Treatment

The eruption of phytophotodermatitis may be accompanied by burning pain and blisters. The acute symptoms usually persist for several days and may be alleviated by therapy with topical corticosteroids. The hyperpigmentation that often develops at the contact site, even without obvious dermatitis, may persist for months. Topical corticosteroids should not be used to treat the hyperpigmentation.

Final Comment

Phytophotodermatitis is a skin eruption that arises following the combination of a photosensitizing compound and ultraviolet light. While an acute phototoxic reaction characterized by erythema and blistering may occur, this is often not the case. In the absence of erythema and blistering, a detailed history of citrus fruit exposure and occupational or recreational exposure to plants may assist in the diagnosis. REFERENCES (1)Fisher AA, Mitchell JC. Dermatitis due to plants and spices. In: Fisher AA. Contact dermatitis. 3d ed. Philadelphia: Lea & Febiger, 1986:434. (2)Seligman PJ, Mathias CG, O’Malley MA, et al., Phytophotodermatitis from celery among grocery store workers. Arch Dermatol 1987;123:1478-82. (3)Berkley SF, Hightower AW, Beier RC, et al. Dermatitis in grocery workers associated with high natural concentrations of furanocoumarins in celery. Ann Intern Med 1986;105:351-5. (4)Oppenheim M. Dermatite bulleuse striee consecutive aux bains de soleil dans les pres dermatitis bullosa striata pratensis. Ann Dermatol Syphil 1932;3:1-7. (5)Harber LC, Harris H, Leider M, Baer RL. Berloque (berlock) dermatitis. Arch Dermatol 1964;90:572. (6)White W. Club Med dermatitis [Letter]. N Engl J Med 1986;314:319-20. (7)Epstein JH. Phototoxicity and photoallergy in man. J Am Acad Dermatol 1983;8:141-7. (8)Harber LC, Bickers DR. Phytophotodermatitis. In: Photosensitivity diseases: principles of diagnosis and treatment. 2d ed. Philadelphia: Saunders, 1989;11-26. (9)Crow KD, Alexander E, Buck WH, et al. Photosensitivity due to pitch. Br J Dermatol 1961;73:220-32. (10)Kaidbey KH, Kligman AM. Topical photosensitizers. Influence of vehicles on penetration. Arch Dermatol 1974;110:868-70.

PHOTO : Phytophotodermatitis (berloque type), resulting from a phototoxic associated with the use

PHOTO : of a perfume containing oil of bergamot.

PHOTO : Pseudoannular, streaky hyperpigmentation of phytophotodermatitis associated with the

PHOTO : topical use of lime juice.

PHOTO : More distant view of patient demonstrating the streaky, linear hyperpigmentation caused by

PHOTO : lime juice running down the leg.

COPYRIGHT 1989 American Academy of Family Physicians

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