Brown recluse spider bite: Difference between revisions

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==Background==
==Background==
[[File:Loxosceles reclusa range.png|thumb|Brown recluse range (yellow area)]]
[[File:Brown Recluse.jpg|thumb|Brown recluse]]
*Brown violin shape on cephalothorax (fiddleback)
*Brown violin shape on cephalothorax (fiddleback)
*In Southern midwestern US
*In Southern midwestern US
* ''Loxosceles'' family
*''Loxosceles'' family


===Mechanism===
===Mechanism===
*Venom contains variety of cytotoxic enzymes causing necrotic wound
*Venom contains variety of cytotoxic enzymes, principally Hyaluronidase and Sphingomyelinase-D, which cause a necrotic wound
**Hyaluronidase: facilitates the penetration of the venom into tissue but does not induce lesion development
**Sphingomyelinase-D:  causes necrosis and lesion formation by initiating the release of pro-inflammatory mediators (thromboxanes, leukotrienes, prostaglandins, and neutrophils)


==Clinical Features==
==Clinical Features==
#Bite is initially painless
[[File:MPX2157 synpic16260.png|thumb|Brown recluse spider bite, day 3.]]
#Mild reaction
[[File:MPX2157 synpic16261.png|thumb|Brown recluse spider bite, day 4.]]
##Most common
[[File:MPX2157 synpic16262.png|thumb|Brown recluse spider bite, day 5.]]
##Mild erythematous lesion that later becomes firm and heals without scar
[[File:MPX2157 synpic16263.png|thumb|Brown recluse spider bite, day 6.]]
#Severe reaction
[[File:MPX2157 synpic16264.png|thumb|Brown recluse spider bite, day 9.]]
##Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling  
[[File:MPX2157 synpic16265.png|thumb|Brown recluse spider bite, day 10.]]
##Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
*Bite is initially painless
##By day 3 or 4 hemorrhagic area may become ecchymotic
*Mild reaction (most common)
###Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
**Mild erythematous lesion that later becomes firm and heals without scar
##By end of first week ecchymotic area may become necrotic w/ eschar formation
*Severe reaction
#Systemic effects
**Begins with mild-severe pain several hours after bite accompanied by erythema and swelling  
##Rare
**Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
##Occur predominantly in children 24-72hr after the bite
**By day 3 or 4, hemorrhagic area may become ecchymotic
###Include nausea/vomiting, fever, arthralgias, DIC, rhabdo, renal failure
***Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
**By end of first week, ecchymotic area may become necrotic with eschar formation
*Systemic effects (rare)
**Occur predominantly in children 24-72hr after the bite
**[[Nausea/vomiting]]
**[[Fever]], [[arthralgia]]
**[[DIC]]
**[[Rhabdo]]
**[[Renal failure]]


==Differential Diagnosis==
==Differential Diagnosis==
{{Bites and stings DDX}}
{{Bites and stings DDX}}


==Workup==
==Evaluation==
*Definitive diagnosis is achieved only when the biting spider is positively identified
*Labs
**May be remarkable for [[hemolytic anemia|hemolysis]], hemoglobinuria, and [[hematuria]]
**[[Coagulopathy]] may be present (elevated fibrin split products, decreased fibrinogen concentrations, and a positive [[D-dimer]])
**Increased PT and PTT


==Management==
==Management==
#Local wound care
*Local wound care and [[tetanus prophylaxis]]
#Abx are indicated only if signs of infection exist; secondary infections are uncommon
*[[Antibiotics]] are indicated only if signs of infection exist; secondary infections are uncommon
#Although some texts recommend Dapsone, it has been shown to be of limited benefit and is associated with hemolysis in G6PD patients and als methemoglobinemia
*Although some texts recommend [[dapsone]], it has been shown to be of limited benefit and is associated with hemolysis (in G6PD patients) and [[methemoglobinemia]]


==Disposition==
==Disposition==
*Typically discharge home


==See Also==
==See Also==
*[[Bites and Stings]]
*[[Spider bites]]


==External Links==
==External Links==


==Sources==
==References==
<references/>
<references/>


[[Category:Environ]]
[[Category:Environmental]]
[[Category:Derm]]
[[Category:Dermatology]]

Latest revision as of 13:26, 29 May 2022

Background

Brown recluse range (yellow area)
Brown recluse
  • Brown violin shape on cephalothorax (fiddleback)
  • In Southern midwestern US
  • Loxosceles family

Mechanism

  • Venom contains variety of cytotoxic enzymes, principally Hyaluronidase and Sphingomyelinase-D, which cause a necrotic wound
    • Hyaluronidase: facilitates the penetration of the venom into tissue but does not induce lesion development
    • Sphingomyelinase-D: causes necrosis and lesion formation by initiating the release of pro-inflammatory mediators (thromboxanes, leukotrienes, prostaglandins, and neutrophils)

Clinical Features

Brown recluse spider bite, day 3.
Brown recluse spider bite, day 4.
Brown recluse spider bite, day 5.
Brown recluse spider bite, day 6.
Brown recluse spider bite, day 9.
Brown recluse spider bite, day 10.
  • Bite is initially painless
  • Mild reaction (most common)
    • Mild erythematous lesion that later becomes firm and heals without scar
  • Severe reaction
    • Begins with mild-severe pain several hours after bite accompanied by erythema and swelling
    • Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
    • By day 3 or 4, hemorrhagic area may become ecchymotic
      • Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
    • By end of first week, ecchymotic area may become necrotic with eschar formation
  • Systemic effects (rare)

Differential Diagnosis

Envenomations, bites and stings

Evaluation

  • Definitive diagnosis is achieved only when the biting spider is positively identified
  • Labs
    • May be remarkable for hemolysis, hemoglobinuria, and hematuria
    • Coagulopathy may be present (elevated fibrin split products, decreased fibrinogen concentrations, and a positive D-dimer)
    • Increased PT and PTT

Management

  • Local wound care and tetanus prophylaxis
  • Antibiotics are indicated only if signs of infection exist; secondary infections are uncommon
  • Although some texts recommend dapsone, it has been shown to be of limited benefit and is associated with hemolysis (in G6PD patients) and methemoglobinemia

Disposition

  • Typically discharge home

See Also

External Links

References

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