Skin-nontumor / Clinical dermatology
Infectious disorders
Anthrax

Author: Cecilia Rosales, M.D. (see Authors page)

Revised: 20 May 2016, last major update July 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Skin AND anthrax

Definition / General
  • Coal in Greek; refers to black coloration of skin eschar
Etiology
  • An uncommon, cutaneous infection due to endospores of Bacillus anthracis, a common soil organism, which typically causes illnesses in animals
Clinical Features
  • Causes cutaneous, pulmonary or gastrointestinal symptoms
  • Cutaneous anthrax is marked by a boil-like lesion that eventually forms an ulcer with a black center
  • Culture: nonhemolytic, nonmotile and ground-glass colonies that retain their shape when manipulated
  • Grows readily on sheep red blood cell agar (no special conditions needed)
  • Gram stain: gram positive, spore-forming rods
Case Reports
Treatment
  • The cutaneous form of anthrax responds well to several antibiotics
  • With treatment, complete recovery from cutaneous anthrax is usual
  • Antibiotics reduce mortality from 20% to less than 1%
Micro Description
  • Eschar shows coagulative necrosis of superificial epidermis and dermis, with prominent edema of underlying viable dermis, frequent focal hemorrhages, intense, reactive-appearing mononuclear inflammatory infiltrates around small vessels and some adnexae
  • Neutrophils only around necrotizing sebaceous glands
  • Sharp demarcation between superficial, necrotic and deeper edematous viable tissue (at periphery); occasional islands of regenerating epidermis under necrotic layer of eschar
  • Vessels with degenerated endothelial cells and focal thrombi
  • No abscess
  • No granulation tissue
Micro Images

Images hosted on other servers:

Figure 1: coagulative necrosis of superficial epidermis and dermis, edema of underlying viable dermis, frequent focal hemorrhage, intense mononuclear inflammation around small vessels and some adnexa
Figure 2: sharp demarcation between superficial necrotic and deeper edematous viable tissue, with occasional islands of regenerating epidermis present under necrotic eschar
Figure 3: mononuclear infiltrate



Bacteria

Additional References