View source for Brown recluse spider bite

==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)
*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==
[[File:MPX2157 synpic16260.png|thumb|Brown recluse spider bite, day 3.]]
[[File:MPX2157 synpic16261.png|thumb|Brown recluse spider bite, day 4.]]
[[File:MPX2157 synpic16262.png|thumb|Brown recluse spider bite, day 5.]]
[[File:MPX2157 synpic16263.png|thumb|Brown recluse spider bite, day 6.]]
[[File:MPX2157 synpic16264.png|thumb|Brown recluse spider bite, day 9.]]
[[File:MPX2157 synpic16265.png|thumb|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)
**Occur predominantly in children 24-72hr after the bite
**[[Nausea/vomiting]]
**[[Fever]], [[arthralgia]] 
**[[DIC]]
**[[Rhabdo]]
**[[Renal failure]]

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

==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==
*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==
*[[Spider bites]]

==External Links==

==References==
<references/>

[[Category:Environmental]]
[[Category:Dermatology]]