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  • 14 Plants and Creatures ofDermatologic Significance Jennifer B. Perone, MDC o n t e n t s14.1 Plant Dermatoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46114.2 Dermatologic Diseases Caused by Creatures . . . 46614.3 Lice, Spiders, Bugs, and Other Creatures . . . . . . . 46914.4 Ticks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47514.5 Mites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47614.6 Exotic Pets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47814.7 Skin Eruptions Caused by Marine Life . . . . . . . . . . 47914.8 Medications Derived from Plants and Creatures . . . 481 Plants and Creatures of Dermatologic Significance459
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  • 14.1 PLANT DERMATOSESContact Urticaria Contact urticaria occurs after direct contact, and can be immunologic (IgE) or non-immuno-logic (toxin-mediated).1 It is a transient eruption characterized by wheals, erythema, and prurituswith burning or stinging caused by direct contact with proteins. Type I hypersensitivity, or IgE mediated reactions, require previ- u TIPous sensitization. Vasoactive mediators are released and lead to local, a topics and food-handlers are A often susceptible to contactor systemic (called contact urticaria syndrome) involvement usu- urticaria 2ally within 30 minutes. Urticants include vegetables, fruits, and manyother plants. Celery (Apium graveolens) is more likely than othercauses to lead to a systemic reaction or anaphylaxis.3Frequent causes of immunologic eruptions such as uTIPlatex proteins (Hevea brasiliensis) may cross react ammunologic (IgE mediated) requires prior sensitization Iwith other plants.4 Processing or cooking of foods aNonimmunologic occurs without prior exposurereduces their allergenicity.5 Nonimmunologic urticaria occurs without previous sensitization in any host. Plants such asstinging nettles (Urtica dioica, Urticaceae family) lead to the release of histamine from mastcells. Toxin urticaria is usually short-lived.6 Sharp hairs on the plants contain toxins (histamine,serotonin and acetylcholine), which are released into the skin causing rapid edema, pruritus andburning.7 One human (and many equine) deaths have been reported from Australian sting-ing nettles (Dendrocnide spp.).8 Other common causes are Euphorbiaceas (spurge nettle) andHydrophyllaceae (water-leaf family) found in the tropical Americas.Irritant Dermatitis Irritant dermatitis can be caused by several mechanisms including mechanical and chemi-cal factors. There is a direct toxic effect of the irritant on the skin without involvement of animmune response. Environmental factors such as humidity and temperature, and host factorssuch as atopy, fissures, sweating and dryness impact the severity of the irritant effect. Clinically,the response is varied ranging from erythema to bullae and even necrosis. Pathologic appearanceparallels the clinical appearance from spongiosis, vesicles and karyorrexis or necrosis.9 Mechanical irritant dermatitis can be caused by direct effects of thorns and barbs. Small glo-chids (barbed hairs or bristles) or large thorns (on cacti for example) can become imbedded intothe skin causing injury and resultant dermatitis. Secondary infection can be caused by microor-ganism inoculation (see Table 14-1). Table 14-1. Microorganism Inoculation (adapted from 8 ) Vector Organism Spines Clostridium tetani Blackthorns Staphylococcus aureus Grasses, sphagnum moss, rose thorns Sporothrix schenckii Blackberries Mycobacterium kansasii Cactus spines M. marinum Spiky tropical vegetation M. ulcerans Plants and Creatures of Dermatologic Significance461
  • Many plant families contain chemicals that cause chemical irritant dermatitis. One of the most common irritants is calcium oxalate; however, a wide range of chemicals exist within plants.10 Calcium oxalate itself is an irritant, and is synergistic with other chemicals, thereby increasing their irritancy. Pineapples contain bromelin, a proteolytic enzyme, which is granted access to dermal vessels by calcium oxalate induced fissures.11 The most common cause of irritant dermatitis in florists is from oxalate alkaloids in the sap of daffodils (Narcissus spp.) present in the stems and bulbs leading to daffodil itch.12 (Figure 14-1) Other plants such as hyacinth and tulips can cause a similar dermatitis, usually manifested by xerosis, erythema and fissures on the fingertips, hands and arms. Patients may try an at-home remedy for onychomycosis by applying garlic cloves to the nails but this may cause irritant dermatitis from thiocyanates in the garlic. (Figure 14-2, 14-3, Table 2) Figure 14-1. Narcissus Spp. Photo courtesy of Britton, NL and Brown A 1913 USDA-NRCS PLANTS Database Figure 14-2. Buttercup (Ranunculaceae) Figure 14-3. Pointsettia (Euphorbiaceae) Photo courtesy of Jennifer Anderson USDA-NRCS PLANTS Database 4622011/2012 Dermatology In-Review l Committed to Your Future
  • Table 14-2. Causes of Plant Irritant Dermatitis (adapted from ) 7 Family or Binomial Name Common Name Irritant Euphorbiaceae Spurges, crotons, poinsettas, Phorbol esters, latex machineel tree Ranunculaceae Buttercup Ranunculin Solanaceae Chili pepper Capsaicin Opuntia vulgaris Prickly pear Alliaceae Garlic Thiocyanates Narcissus spp. Daffodil Calcium oxalate Brassicaceae Mustard, radish Thiocyanates Ananas comosus Pineapple Bromelin, calcium oxalate Lilaceae Hyacinth Calcium oxalateAllergic Contact Dermatitis When the skin mounts a specific immune response to an u TIPallergen, the result is an allergic contact dermatitis (ACD). aSkin mounts specific immune response to an allergenLangerhans cells in the epidermis present the antigen to primed aType IV cell-mediated delayed CD4+ T lymphocytes and there is a resultant local dermati- hypersensitivitytis or a type IV, cell-mediated delayed hypersensitivity reac-tion. Histopathologically, an acute spongiotic dermatitis that may have vesicles containingLangerhans cells and a predominantly lymphohistiocytic infiltrate is seen.13 A variable number ofeosinophils may be seen. Many plants are causes of allergic contact dermatitis. Some of the most common include car-riers of the rhus antigen pentadecacatechol (found in poison ivy, oak and sumac) and sesquiter-pene lactones in the Compositae family.14 (Figures 14-4, 14-5, 14-6; Table 3) Rhus antigen causesan acute, often streaky or linear reaction with an erythematous and edematous possibly vesiculardermatitis. In contrast, tuliposide A (in Alstroemeria) causes a hyperkeratotic or lichenified plaquein the area of contact, usually the finger. (Figure 14-7) Sensitization to sesquiterpene lactones mayoccur after use of compositae-containing products and cosmetics such as tea-tree oil.15 (Figures14-8, 14-9) Figure 14-4. Poison Ivy Figure 14-5. Poison Oak Photo courtesy of Robert H. Mohlenbrock Photo courtesy of Robert H. Mohlenbrock USDA-NRCS PLANTS Database/USDA SCS. 1991 USDA-NRCS PLANTS Database/USDA SCS. 1991 Plants and Creatures of Dermatologic Significance463
  • Figure 14-6. Poison Sumac Figure 14-7. Alstromeria