Blue Star flower: New source of contact dermatitis

Newport Beach, Calif. - Based on two cases, Japanese dermatologist Hideo Nakayama, M.D. has identified the Blue Star flower (Oxypetalum caeruleum) as a new sensitizer for contact dermatitis.

"It's important for dermatologists to be aware of the flower, because they may encounter the same disease in their daily clinical activities," Dr. Nakayama says.

Sensitization to Blue Star (more commonly described as "Tweedia") was previously unknown. The appearance of dermatitis on two patients in the floral trade led Dr. Nakayama to suspect the source might be an occupational allergen.

Case histories Patient No. 1 was a 26-year-old female. Patient No. 2 was a 34-year-old male. Both had histories of atopic dermatitis dating to early childhood; however, their conditions had been well controlled prior to entering the floral trade.

Onset of dermatitis was three months prior for the female and seven years prior for the male. The male had been treated with corticosteroid ointments by another dermatologist whenever he suffered a relapse. Eventually, his condition worsened to such an extent that he visited Dr. Nakayama's clinic in Tokyo.

Lab work CBC and liver function tests were normal. Serum IgE levels were 47 IU/mLfor the female patient and 1,200 IU/mL for the male.

To identify the sensitizer, Dr. Nakayama determined what materials patients were handling on a routine basis. He then selected suspect plants and performed patch tests. For Blue Star, he used a white fluid that oozed from the cut stalk.

The fluid produced strong positive allergic reactions that lasted nearly two weeks without inducing a reaction in three controls. Dermatitis resolved two weeks after contact was eliminated. The problem did not recur.

"The causative allergen in Blue Star has not been clarified, even though the fluid was fractionated by column chromatography and patch tested," Dr. Nakayama says.

He adds, "The allergen appears to be easily oxidized or degraded during the process of extraction and fractionation."

Oxypetalum caeruleum Indigenous to South America, Tweedia has unique sky-blue, star-like flowers. According to Dr. Nakayama, it is widely used by Japanese florists.

Allan Armitage, professor of horticulture at the University of Georgia in Athens, is an international authority on cut flowers. He says, "Tweedia is available in the United States, but not widely used by florists because the plant isn't terribly well known."

He does point out, however, that home gardeners are beginning to appreciate and use the flower.

The threat of contact dermatitis does not concern Mr. Armitage. He explains that several well-known plants, such as poinsettia and primrose, can cause dermatitis if handled repeatedly. He speculates that only frequent handlers will develop an allergic response to Tweedia.

Christine Haller, former board member of the Association of Specialty Cut Flower Growers, notes that growers are likely to have the greatest exposure.

"They cut plants in the field when the staff is freshest, then process flowers by pulling off foliage and putting on rubber bands," she says.

Wholesalers could also have repeated contact, when they recut the stem to keep the flowers fresh or arrange Tweedia in mixed bouquets. Florists and consumers are also likely to cut stems and remove leaves.