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THE NEW ZEALAND
MEDICAL JOURNAL
Vol 120 No 1259 ISSN 1175 8716
NZMJ 10 August 2007, Vol 120 No 1259 Page 1 of 5
URL: http://www.nzma.org.nz/journal/120-1259/2658/ © NZMA
Phytophotodermatitis caused by contact with a fig tree
(Ficus carica)
José G B Derraik, Marius Rademaker
Abstract
Two arborists presented acutely with blistering eruptions affecting their forearms,
hands, and fingers. The previous day, both men had pruned branches from a large fig
tree, Ficus carica, which had sustained damaged during a storm. The following
morning, both complained of a burning discomfort which rapidly evolved into
erythema and bullae on skin that had been in direct contact with the tree branches.
These symptoms gradually resolved over 4 to 6 weeks. Although phytophotodermatitis
from Ficus carica has been reported, it is often poorly recognised and there is a need
to raise awareness amongst arborists, orchardists, forestry workers, gardeners, and
health professionals.
Plant dermatitis (phytodermatitis) is caused by a reaction in the skin following contact
with certain plants or plant parts. They can be irritant such as cactus spine injuries,
urticarial (e.g. from stinging nettles), allergic from plants such as Primula obconica or
Toxicodendron succedaneum, or they can be phytophototoxic in nature.
1
Phytophotodermatitis is generally a toxic reaction due to direct skin exposure to
certain plants or plant parts, followed by exposure to ultraviolet (UV) light. The most
common plants to cause phytophotodermatitis belong to the Apiaceae (Umbelliferae)
family.
1
Other plant families that can cause phytophotodermatitis include Rutaceae,
Moraceae, and Fabaceae.
Case report
Two male arborists were cleaning up storm damaged limbs from a large fig tree, Ficus
carica, which was heavily laden with fruit (e.g. Figures 1 and 2). The work took place
in Auckland between 10:30 am and noon, on a dry, relatively clear summer day (80%
relative humidity, temperature 24°C, total UV exposure in 1.5 hours 3.58 mJ).
Both workers were dressed in short-sleeved shirts or singlets. During the removal of
the storm damage, they wrapped their arms (predominantly their right arms) around
the fig tree branches when dragging them to the wood chipper.
Some 9 hours later, the first arborist noted a burning sensation on his right arm, which
he attributed to sunburn. However, over the next 12 hours, the skin on this arm became
swollen, erythematous, and was sore to touch. Within 24 hours of contact with fig tree
parts, bullae appeared on the forearm, wrist, and back of the hand
NZMJ 10 August 2007, Vol 120 No 1259 Page 2 of 5
URL: http://www.nzma.org.nz/journal/120-1259/2658/ © NZMA
Figure 1. The fig tree, Ficus carica
(Photo courtesy of Petr Kocna)
Figure 2. The leaves and fruit of
Ficus carica (Photo courtesy of Petr Kocna)
Figure 3. Second arborist’s forearm approximately 36 hours (A), 48 hours (B), 72 hours (C), 12
days (D), and 35 days (E) after contact with Ficus carica tree branches and exposure to sunlight.
(Photos courtesy of Alex White and Gerald Collett)
(A) (B) (C) (D) (E)
Note: In the photos a ‘ring’ can be observed in the wrist region where an armband presumably prevented exposure to
sunlight and the consequent occurrence of phototoxic reaction.
These symptoms on the first arborist persisted for over 2 weeks despite the use of
alternative remedies, including a mixture of lavender oil and Aloe vera gel. As the
acute erythema settled, post-inflammatory pigmentation developed, which slowly
resolved over a month.
The second worker also experienced a burning sensation on his right forearm some 9
hours after working with the fig tree. Blistering of skin was noticed approximately 31
hours after contact with the fig tree (Figure 3), at which point the arborist covered the
blisters and bullae with manuka honey. His condition progressively worsened with
swelling and formation of large bullae on the affected arm (Figure 3). Circa 51 hours
after contact with the plant, he attended the accident and emergency (A&E)
NZMJ 10 August 2007, Vol 120 No 1259 Page 3 of 5
URL: http://www.nzma.org.nz/journal/120-1259/2658/ © NZMA
department at the local hospital. Initially the pain and blistering were restricted to the
arm which had been wrapped around the fig branches—but subsequently he developed
pain and swelling on the left arm, chest, and legs which had also been in contact with
the fig tree. The discomfort progressed such that he was unable to work for
approximately 10 days.
He responded slowly to topical corticosteroids and oral non-steroidal anti-
inflammatories. The symptoms gradually resolved over 4 to 6 weeks (Figure 3).
Discussion
The history and clinical appearances was pathognomonic of a phytophotodermatitis
which, in these two cases, was secondary to contact with the fig tree.
Phytophotodermatitis is the interaction of plant compounds, most often psoralens,
with sunlight on human skin; this results in an acute dermatitis.
1
It is usually a
phototoxic reaction, as opposed to a photoallergic reaction. As a result, no prior
sensitisation is necessary and anybody can be affected.
2
Other types of
phytodermatitis include urticarial dermatitis, irritant contact dermatitis, and allergic
contact dermatitis.
The eruption of phytophotodermatitis usually begins 24 hours after exposure and
peaks at 48–72 hours. Phytophototoxicity may be amplified by both humidity and
perspiration. It typically manifests as a burning erythema that may subsequently
blister, and post-inflammatory hyperpigmentation lasting weeks to months may ensue.
In some patients, the preceding inflammatory reaction may be mild and go
unrecognised by the patient.
Phytophotodermatitis occurs most commonly in the spring and summer when
furocoumarins are at their highest concentration in plants, and when UV levels are
also at their peak. The incidence of phytophotodermatitis is unknown, but will vary
according to the risk of exposure to psoralens. Because furocoumarins are found in a
wide range of wild and domestic plants (Table 1), a variety of patient groups may
become exposed.
Table 1. Examples of plants known to cause phytophotodermatitis, and the main sensitising
compounds associated with them
Family Species Common Names Main Compounds
Apiaceae Ammi majus
Apium graveolens
Heracleum sphondylium
Heracleum mantegazzianum
Pastinaca sativa
Bishop's weed, large bullwort
Celery
Cow parsnip, common hogweed
Giant hogweed
Parsnip
5-MOP, 8-MOP, imperatorin
Psoralens, 5-MOP, 8-MOP
5-MOP, 8-MOP, imperatorin, phellopterin
5-MOP, 8-MOP, imperatorin,
5-MOP, 8-MOP, imperatorin, isopimpinellin
Fabaceae Psoralea corylifolia Babchi, scurf pea Psoralens
Moracea Ficus carica Fig Psoralens, 5-MOP
Rutaceae Citrus bergamia
Citrus maxima
Dictamnus albus
Bergamot
Pomelo, pummelo, shaddock
Gas plant
5-MOP
5-MOP
5-MOP, 8-MOP
5-MOP = 5-methoxypsoralen, 8-MOP = 8-methoxypsoralen.
The two cases presented were at very high risk of developing phytophotodermatitis
because of their prolonged and significant contact, high summer levels of
NZMJ 10 August 2007, Vol 120 No 1259 Page 4 of 5
URL: http://www.nzma.org.nz/journal/120-1259/2658/ © NZMA
furocoumarins in the plant, peak summer UV levels, exposed skin, warm temperature,
and perspiration.
Whilst photoallergic reactions are a cell-mediated immune response in which the
antigen is the light-activated photosensitising agent, phototoxic reactions result from
direct damage to tissue caused by light activation of the photosensitiser.
The main photosensitisers in plants are furocoumarins and consist of psoralens (5-
methoxypsoralens, 8-methoxypsoralens), angelicin, bergaptol, and xanthotal (Table
1).
1–3
The photochemical excitation of these furocoumarins is induced by UV radiation,
usually within the UVA wavelengths of 320–400 nm (peak activity is around 335
nm).
13
Two types of toxic reactions occur: one oxygen-independent, where the UV-activated
furocoumarins bind to RNA and nuclear DNA; and the other: an oxygen-dependent
reaction where the induced compounds cause cell membrane damage and oedema.
1,3–6
These reactions consequently lead to cell death (sunburnt cells and apoptotic
keratinocytes).
Ficus carica, which is believed to have originated in western Asia, was brought to the
Mediterranean as early as 5000 BC. In New Zealand, it is commonly cultivated as a
fruit tree in home gardens and appears to be widespread in the North Island
(particularly in northern regions); it can also be found in some areas of the South
Island, particularly in those areas that experience long, hot summers (Melanie
Newfield, personal communication, 2007).
Ficus carica belongs to the Mulberry family (Moraceae). The leaves and unripened
fruit of figs contain the furocoumarins, psoralen, and bergapten, as well as the
coumarins, umbelliferone, 4',5'-dihydropsoralen, and marmesin. The furocoumarins
are lipid-soluble and can penetrate the epidermis with ease.
7–10
There are a number of other Ficus species which may cross react with F. carica
including Weeping fig (F. benjamina), Cluster fig (F. racemosa), and Sycamore Fig
(F. sycomorus).
Eating figs does not cause photosensitisation, unless the juice is smeared onto the face.
However, anaphylaxis has been reported after eating figs; in some of these cases, this
may represent a cross-reaction with natural rubber latex.
11–12
Although phytophotodermatitis from Ficus carica has been previously reported, it is
often poorly recognised. As the cases reported here illustrate, contact with fig and
other plant sources of furocoumarins can cause severe local reactions.
It is important that awareness is raised amongst the general public—especially those
people whose occupations lead to a greater likelihood of exposure: arborists,
orchardists, forestry workers, and gardeners.
Author information: José G B Derraik, Senior Adviser (Human Health), MAF
Biosecurity New Zealand (NZ), Ministry of Agriculture and Forestry, Wellington;
Marius Rademaker, Hon Associate Professor, Department of Dermatology, Waikato
Hospital, Hamilton
NZMJ 10 August 2007, Vol 120 No 1259 Page 5 of 5
URL: http://www.nzma.org.nz/journal/120-1259/2658/ © NZMA
Acknowledgements: We are grateful to Gerald Collett, Alex White, and Ian Barnett
(Treecare Services Ltd, Auckland) for providing us with the precise details of the case
as well as the very useful photographs, which made this case report possible. We also
thank Petr Kocna for allowing us to include his photographs in this article, and
Melanie Newfield (MAF Biosecurity NZ) for relevant information. Climate data were
kindly supplied by National Institute of Water and Atmospheric Research (NIWA).
Correspondence: Dr José G B Derraik, MAF
Biosecurity NZ, Ministry of Agriculture
and Forestry, PO Box 2526, Wellington. Fax: (04) 894 0733; email:
jose.derraik@maf.govt.nz
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This case report was corrected on 7 September 2007 to reflect the Erratum at
http://www.nzma.org.nz/journal/120-1261/2720
