Observations on the idioblasts of Dieffenbachia

Epipremnum aureum Keratopathy: Case Report and Review of the Literature

OBJECTIVES

To report a novel case of Epipremnum aureum toxicity masquerading as bilateral infectious keratitis and review the literature on ocular manifestations of Epipremnum exposure.

METHODS

Case report and literature review.

RESULTS

A 70-year-old man with a history of photorefractive keratectomy presented with a 3-day history of bilateral eye pain. The patient reported exposure to plant debris while performing yard work and also water exposure while cleaning his coral fish tanks. Clinical examination revealed bilateral epitheliopathy progressing to frank epithelial defects with underlying stromal necrosis 6 days after exposure. Empiric topical antibiotic drops were initiated, but multiple cultures, corneal biopsy, and confocal microscopy were all negative for an infectious agent. Over a 2-week period, the epithelial defects worsened and a suspicion for a toxic etiology was raised. The patient later recalled rubbing his eyes after exposure to Epipremnum aureum (Golden Pothos/Devils Ivy) sap. He was thus treated conservatively with artificial tears, topical corticosteroids, and amniotic membrane. After 3 months, the epithelial defects resolved, but with corneal scarring, prominently in the left eye and underwent penetrating keratoplasty. Five years after presentation, best-corrected visual acuity with hard contact lenses was 20/25 in the right eye and 20/20 in the left eye.

CONCLUSION

Epipremnum aureum toxicity is a rare cause of keratitis. It can mimic acanthamoeba keratitis or anesthetic abuse and should be considered in cases of culture negative nonhealing corneal ulcerations. Eliciting a history of plant sap exposure can facilitate appropriate supportive care for this toxic keratitis.

Oral Mucosal Irritating Plant Ingestion in Hong Kong: Epidemiology and Its Clinical Presentation

Objective

To study the local epidemiology and clinical presentation after ingestion of oral mucosal irritating plants.

Methodology

Cases presenting with immediate oral mucosal irritation after plant product ingestion from July 2005 to June 2009 were retrieved from the Hong Kong Poison Information Centre's clinical database. Their clinical features and management were reviewed.

Results

Thirty cases were retrieved and analysed, including 14 males and 16 females. Poisoning occurred all year round with no seasonal predilection. Vomiting and dysphagia were the two most common symptoms other than immediate oral mucosal irritation. Half of the cases could be managed with symptomatic treatment and discharged after a few hours of observation. Six patients presented with angioedema and were managed initially with the use of intravenous steroid, antihistamine and with or without adrenaline. Urgent airway assessment with laryngoscope was performed in 3 patients. No patient required endotracheal intubation.

Conclusion

Oral mucosal irritating plant ingestion is not uncommon in Hong Kong. Its clinical feature can mimic angioedema on presentation. Immediate and localized oral mucosal symptoms after plant product ingestion are the key to diagnosis.

Severe destruction of the upper respiratory structures after brief exposure to a dieffenbachia plant

Dieffenbachia is a common domestic plant. Oral contact with the plant generally causes slight effects, but when chewed it may result in painful oropharyngeal edema. Even though the mechanism through which this plant causes toxicity is not known, calcium oxalate crystals (rhaphides) and protease in the idioblast of the plant are considered to be the causes. Our aim was to show the lethal effects of a common domestic plant named Dieffenbachia.A 70-year-old male patient applied to our clinic with aphasia, dysphagia, sialorrhea, wounds on the lips and tongue, and swelling on the face. There was edema on his tongue, soft palate, uvula, anterior pharyngeal plica, epiglottis and aryepiglottic fold, and ulceration on the right side of his tongue, the right cheek mucosa, right-lower gingival, soft palate, tongue base, epiglottis anterior surface, and free edge.Dieffenbachia toxicity presents both minimal and serious problems, which can be life threatening, as in our case. Toxic cases resulting in serious clinical pictures due to Dieffenbachia are rare.

Outbreak of Food-borne Illness Associated with Plant Material Containing Raphides

BACKGROUND

Many botanicals, particularly ornamental house-plants, contain crystals of calcium oxalate called raphides. Raphides have known toxic effects when chewed, including painful edema, vesicle formation, and dysphagia. We report a food-borne illness outbreak associated with ingestion of raphides.

METHODS

On February 24, 2003, the Chicago Department of Public Health was notified of multiple cases of oral burning and facial edema associated with lunch in an office cafeteria on February 21. The investigation included a case-control study, interviews with kitchen staff, an environmental inspection, and laboratory analysis of leftover foods.

RESULTS

Ten cases were identified, including one admitted to the Intensive Care Unit for potential airway obstruction secondary to severe edema, and another seen by Emergency Department staff for oral edema and pain. Ten of 10 case-patients reported oral stinging and burning, and 8 of 10 reported dysphagia. Four of 10 case-patients continued to have symptoms 2 weeks later. Food from the cafeteria's international buffet was consumed by 10 of 10 case-patients and by 1 of 22 control subjects (odds ratio=undefined); each of the 10 case-patients reported consumption of a Chinese vegetable entrée from the international buffet and had no other foods in common. Plant material from the Chinese vegetable entrée contained raphides.

CONCLUSION

This outbreak was associated with consumption of raphides resembling those from common botanicals. Clinicians and public health practitioners should be aware of raphide-containing plants as a potential cause of food-borne illness.

Plant poisoning

Each year over 100,000 exposures to toxic plants are reported to poison centers throughout the United States. Most of these exposures are of minimal toxicity largely because of the fact that they involve pediatric ingestions, which are of low quantity. The more serious poisonings usually involve adults who have either mistaken a plant as edible or have deliberately ingested the plant to derive perceived medicinal or toxic properties. The plants within this manuscript have been chosen because they have been documented to cause fatalities or account for emergency medicine visits. In this discussion, plants are grouped by their toxins rather than on the basis of their taxonomy.

Calcium oxalate in plants: formation and function

Calcium oxalate (CaOx) crystals are distributed among all taxonomic levels of photosynthetic organisms from small algae to angiosperms and giant gymnosperms. Accumulation of crystals by these organisms can be substantial. Major functions of CaOx crystal formation in plants include high-capacity calcium (Ca) regulation and protection against herbivory. Ultrastructural and developmental analyses have demonstrated that this biomineralization process is not a simple random physical-chemical precipitation of endogenously synthesized oxalic acid and environmentally derived Ca. Instead, crystals are formed in specific shapes and sizes. Genetic regulation of CaOx formation is indicated by constancy of crystal morphology within species, cell specialization, and the remarkable coordination of crystal growth and cell expansion. Using a variety of approaches, researchers have begun to unravel the exquisite control mechanisms exerted by cells specialized for CaOx formation that include the machinery for uptake and accumulation of Ca, oxalic acid biosynthetic pathways, and regulation of crystal growth.

Acute airway compromise after brief exposure to a Dieffenbachia plant

Dieffenbachia is a common domestic plant. Oral contact with the plant usually is associated with minimal consequences. However, chewing on the stem or the leaf of the Dieffenbachia can result in painful oropharyngeal edema and the inability to speak or handle secretions. Airway compromise has been reported only in a pediatric ingestion. We report a case of an adult who bit into the stem of the plant thinking it was sugar cane. He instantly spit out the remaining stem and despite this brief exposure, oropharyngeal edema developed refractory to medicinal therapy, requiring surgical airway management. The exact mechanism of edema is not known; therefore, methods of treatment are variable. We recommend caution when presented with a patient exposed to Dieffenbachia. Even the patient who initially seems stable may have an airway that will quickly deteriorate.

Distribution of calcium oxalate crystals in the secondary phloem of conifers: a constitutive defense mechanism?

•   Calcium oxalate (CaOx) crystals were studied in the secondary phloem of 46 conifer species from six families to characterize their distribution relative to defense. •   Scanning electron microscopy, and polarized light microscopy of stem tissue allowed analysis of the quantity, location, morphology and size of the crystals. •   Vastly different patterns of CaOx crystal deposition were observed in stems of Pinaceae and nonPinaceae lineages. The CaOx crystals were present in all species but the highest density occurred along the nonPinaceae lineage. In Pinaceae, all species accumulated crystals intracellularly in crystalliferous parenchyma, whereas all nonPinaceae species had only extracellular crystals. A possible relationship between the number of aggressive bark beetles species and the amount of CaOx accumulation was noted where increased crystal accumulation appears to be antagonistic to beetle attack. Mapping along with this trend was the presence of phloem fibers. •   We conclude that in conifer stems the patterns and frequency of CaOx crystals function as a constitutive defense and in combination with fiber rows, provides an effective barrier against small bark-boring insects.

Injury to the oral mucous membranes caused by the common houseplant, dieffenbachia. A review

The common houseplant, dieffenbachia, causes painful edematous swelling of the oral mucous membranes when chewed. This property, which is well known to the staffs of poison control centers, can be dangerous to the unwary or to victims of practical jokes. The microscopic features of the injury are those of acute inflammation, but the nature of the plant's toxicity remains controversial. The numerous needles (raphides) of calcium oxalate, which are contained in specialized cells (idioblasts) in the plant, and proteases have both been implicated. When stimulated, the idioblasts fire the raphides with some force for a distance of two to three cell lengths. One possibility is that the local toxicity of dieffenbachia may be caused by a combination of this mechanical release of the raphides, which results in traumatic injury, and the effects of a chemical toxin carried on their surfaces and in their grooves.