Authors: Jason Tang, Medical Student, University of New South Wales; Dr Monisha Gupta, Dermatologist, Liverpool Hospital, and Senior Conjoint Lecturer, University of New South Wales. DermNet NZ Editor in Chief, A/Prof Amanda Oakley, November 2017.
Bindii is the Australian name for a prickly annual weed. It is low growing plant that is widely established on lawns and in flower beds. The name is used to refer to several species, particularly Soliva pterosperma and Soliva sessilis. Other names for bindii are bindi, bindyi, Jo-Jo, bindi-eye, and, in New Zealand, Onehunga weed, prickle weed and burrweed.
The bindii weed originated in South America, and has since naturalised in Australia, New Zealand, Portugal, Spain, and southern USA.
Bindii dermatitis is a form of irritant contact dermatitis due to injury by the seed of the bindii weed.
Bindii dermatitis may affect anyone. It most often affects boys 5 to 18 years of age, possibly because of their active lifestyle involving outdoor sports.
The risk of dermatitis may be increased if there is a family history of bindii dermatitis.
Bindii dermatitis most often occurs in late spring and early summer and is less frequent during winter when the bindii weed becomes dormant.
The spine of the bindii seed penetrates the skin causing a sharp prick. Over the next few days, the skin around the spine becomes inflamed forming discrete red papules with a central puncture site.
The severity of the dermatitis depends on:
Some patients may develop an immediate wheal reaction when pricked by the bindii weed; this can resolve without progressing to dermatitis.
Bindii dermatitis is a clinical diagnosis made through taking a thorough medical history and examination. There is no specific test.
Histology of a skin biopsy of bindii dermatitis shows spongiosis, mixed dermal infiltrate and foreign body giant cells. There may be marked oedema of the papillary dermis and draining sinuses. Evidence of plant material may be present.
Visible prickles should be manually removed.
Bindii dermatitis can be prevented by avoiding contact with the bindii weed.
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