[Cutaneous loxoscelism with edematous predominance]

Area of Science:

• Toxicology
• Dermatology
• Arachnology

Background:

• Loxoscelism, caused by Loxosceles spider venom, presents clinically as cutaneous (CL) or viscerocutaneous (VCL) forms.
• In Chile, Loxosceles laeta spiders commonly cause loxoscelism, with CL and VCL occurring in 83.3% and 16.7% of cases, respectively.
• A subset of CL, known as cutaneous loxoscelism with edematous predominance (CLEP), is characterized by significant edema, particularly on the face, with minimal or no necrosis.

Observation:

• This study analyzes 10 cases of CLEP (4 males, 6 females; ages 6-68) in Chile, predominantly occurring in warmer months.
• Patients presented 4-24 hours post-bite with stinging, pain, and progressive edema, sometimes involving the entire face, neck, and thorax.
• Clinical manifestations included intense, painful, rose-colored edema, occasionally accompanied by small blisters or livedoid plaques that resolved without scarring.

Findings:

• CLEP accounts for approximately 4% of loxoscelism cases and exhibits a benign prognosis.
• Parenteral administration of chlorprophenpyridamine maleate (antihistamine) resulted in significant pain and edema reduction within 4-10 days.
• The study suggests that the pronounced edema in CLEP might mitigate the necrotic effects of L. laeta venom.

Implications:

• CLEP represents a distinct clinical presentation of Loxosceles envenomation with a favorable outcome.
• Prompt antihistamine therapy is effective in managing CLEP symptoms, reducing pain and edema.
• Differential diagnosis in Chile should consider insect bites, bee stings, Chagas disease, and angioneurotic edema.