Persistent toxic reactions in a toddler with a negative blood cantharidin toxicology test

Zhu yan Duan ¹ Qu Yanning ¹ Rui Tang ² Meng yi Sheng ¹ Liang liang Wang ¹ Jiao Li ² Linying Guo ^1* Si Zheng ^2*

• ¹ Department of Critical Care Medicine, Children's Hospital of Capital Institute of Pediatrics, Beijing, Beijing Municipality, China
• ² Institute of Medical Information, Chinese Academy of Medical Sciences and Peking Union Medical College, Dongcheng, China

Cantharidin is a potent natural toxin and has been used in traditional Chinese medicine to treat cancers and various ailments such as rabies or psoriasis. However, improper use of cantharidin can easily lead to poisoning. Despite there is an increasing amount of literature on the toxic mechanisms of cantharidin, there is still limited knowledge about the disease progression, toxic reactions and toxic blood concentrations in children with cantharidin poisoning. Caregivers of children suffering from cantharidin poisoning might fail to provide an accurate exposure dose when the children exhibit symptoms of intoxication. Moreover, the detection results on routine blood drug screens may be negative, thus delaying the clinical diagnosis and treatment. This study describes a case of cantharidin poisoning in a 2-year-old boy who ingested a traditional Chinese herbal remedy for dog bites. The toddler exhibited severe symptoms related with digestive and urinary systems. Though cantharidin was no longer detectable in the blood 20 hours after admission, the poisoning symptoms persisted for approximately 5 days, and ultrasound showed that there was still sediment in the bladder two weeks after discharge. This case highlights the need for clinicians to consider the widespread tissue distribution of cantharidin, which may lead to prolonged toxic reactions.