Cytotoxic spider bites – cases of mistaken identity
Background: In South Africa, the medically important cytotoxic spiders include the Cheiracanthium (sac) and Loxosceles (violin) species. The diagnosis of necrotic arachnidism is difficult because bites are often unwitnessed and lesions nonspecific. Furthermore, many patients will claim that spider bites are the cause of their skin lesions.
Methods: Prospectively collected cases that were originally reported as spider bites were followed to describe the clinical progression of these lesions until a definitive diagnosis was established.
Results: Six cases of suspected cytotoxic spider bites were identified. One of these cases was confirmed as a sac spider bite resulting mainly in pain and redness, whereas an alternative diagnosis was established in the other five cases, including folliculitis, varicose eczema, adverse reaction to medications and an atypical ischaemic ulcer.
Conclusions: Many spider species are found around the house, but few will be responsible for bites and significant clinical effects. The progression of skin lesions should be monitored to differentiate between a wound caused by the bite of cytotoxic spiders and skin lesions due to other aetiology. Physicians should be educated in cytotoxic spider bites to improve the diagnostic yield and therapeutic management plan of suspected spider bites.