2. Ecthyma gangrenosum
• Cutaneous infection most commonly associated with
Pseudomonas bacteremia
• Pts who are critically ill and immunocompromised
• Characteristic lesions of ecthyma gangrenosum are
hemorrhagic pustules that evolve into necrotic ulcers
• Painless, round, red patches in the skin which rapidly become
pustular with surrounding redness
• Gangrenous ulcer with a black/gray scab surrounded by a red
halo
• Mainly affects the anogenital area and armpits
5. Workup
• Gram stain of fluid from the central
haemorrhagic pustule or blister can rapidly
indicate the diagnosis
• Blood cultures prior to antibiotics
• Skin biopsy:
– Histopathology shows vascular necrosis with few
inflammatory cells but many surrounding bacteria
– Gram negative rods seen surrounding necrotic
vessels
9. Workup
• No specific serologic testing available
• Histopathologic findings not specific, but may
be suggestive of the diagnosis in right clinical
context
– Tissue neutrophilia without significant
leukocytoclastic vasculitis
• Must exclude other mimicking conditions
– Infection, vascular insult, malignancy
10. Treatment
• Systemic immunosuppressive medication is
mainstay
• Topical and local therapy as indicated
• Treatment of causative systemic illness as
indicated
– IBD, arthritis, malignancy
11. Acute Febrile Neutrophilic
Dermatosis
• Commonly known as Sweet Syndrome
• Characterized by acute onset of fever, neutrophilia,
with erythematous, tender skin lesions
• All manifestations resolve rapidly with initiation of
systemic corticosteroids
• Multiple types
– Classical: associated with upper
respiratory/gastrointestinal infections, IBD, pregnancy
– Malignancy-associated: undiagnosed hematologic
malignancy or suggestive of recurrence of known
hematologic malignancy
– Drug-induced: typically due to G-CSF
15. Erysipelas
• Superficial cutaneous cellulitis with marked dermal
lymphatic vessel involvement
• Classically caused by Group A streptococci
– Can be caused by Staphylococci, Group C/G strep
• Differences between erysipelas and classic cellulitis
– Sharply defined borders
– Erythema classically bright red
– Skin can be described as peau d’orange
• Distribution
– 70-80% of cases involve lower extremities
– Up to 10% involve face
• Classically start unilaterally but tend to cross nasal bridge and involve
face symmetrically
18. Treatment
• Depends on severity and presumed causative organism
• Choice of antibiotic should reflect local resistance
patterns
• Outpatient
– Penicillinase-resistant PCN/oral cephalosporin for
suspected non-MRSA
– TMP/SMX, clindamycin, doxycycline, fluoroquinolone for
suspected MRSA
• Inpatient
– IV forms of outpatient abx for suspected non-MRSA
– IV vancomycin for suspected MRSA
