RT Book, Section
A1 Zafren, Ken
A1 Thurman, R. Jason
A1 Jones, Ian D.
A2 Knoop, Kevin J.
A2 Stack, Lawrence B.
A2 Storrow, Alan B.
A2 Thurman, R. Jason
SR Print(0)
ID 1181050966
T1 Brown Recluse Spider Envenomation
T2 The Atlas of Emergency Medicine, 5e
YR 2021
FD 2021
PB McGraw-Hill
PP New York, NY
SN 9781260134940
LK accessmedicine.mhmedical.com/content.aspx?aid=1181050966
RD 2024/04/19
AB The  brown  recluse  spider  (Loxosceles  reclusa)  is  the  prototypical  member  of  the  genus  Loxosceles,  which  as  a  group  can  produce  necrotic  arachnidism  following  envenomation.  These  small  spiders  (approximately  1  cm  in  body  length  and  3  cm  in  leg  length)  have  a  worldwide  distribution  and  are  identified  by  fiddle-shaped  markings  on  their  anterodorsal  cephalothorax.  Initial  envenomation  may  be  painful,  although  patients  often  report  no  recollection  of  being  bitten.  Initial  stinging  gives  way  to  aching  and  pruritus.  The  wound  then  may  become  edematous,  with  an  erythematous  halo  surrounding  a  violaceous  center.  The  erythematous  margin  often  spreads  in  a  pattern  influenced  by  gravity,  leaving  the  necrotic  center  near  the  superior  aspect  of  the  lesion.  Bullae  may  erupt,  and—over  a  period  of  2  to  5  weeks—the  eschar  sloughs,  leaving  a  deep,  poorly  healing  ulcer.  In  approximately  10%  of  cases,  systemic  symptoms  (loxoscelism)  are  present.  Systemic  features  of  brown  recluse  envenomation  may  include  fever,  nausea,  vomiting,  headache,  morbilliform  rash,  arthralgias,  and,  in  severe  cases,  hemolytic  anemia,  coagulopathy,  renal  failure,  and  even  death.  Children  are  at  higher  risk  of  systemic  disease.