see also:

• necrotizing fasciitis
• acute scrotal pain or swelling
• ano-rectal pain
• perianal abscess
• gas gangrene / Clostridial myonecrosis
• Clostridium sp.

• a form of necrotizing fasciitis arising in the perineum or external genitalia - often starting in the scrotum
• first described by Baurienne in 1764
• named after a French venereologist, Jean Alfred Fournier, following five cases he presented in clinical lectures in 1883
• has a relatively high mortality rate with rates quoted from 7% to 30%

• mainly older men with approx 1 in 60,000 men affected per annum and men 40x more likely than women
• males 50 to 79 years old had the highest rate at 3.3 per 100,000 per annum
• can also affect children

• usually due to a synergistic polymicrobial mixed aerobic and anaerobic infection often involving Clostridium perfringens and may also involve invasive Group A Strept (GAS)
• common entry points for the bacteria include:
  • urinary tract infections
  • perianal or vulvar abscesses
  • surgical wounds
  • trauma (eg. scratches, piercings, or injuries during sex)
  • colorectal issues such as fistulas or diverticulitis
  • injections in the region
  • dermatologic / hygiene issues
• ~25% have no clear trigger

• one third of patients were alcoholic, diabetic, and malnourished
• another ten percent were immunosuppressed through chemotherapy, steroids, HIV / AIDS, or malignancy
• 20-70% have diabetes
• obesity
• liver disease
• kidney disease
• substance use
• it is a rare side effect of gliflozins / SGLT2 inhibitors (canagliflozin, dapagliflozin, and empagliflozin) which increase the excretion of glucose in the urine

• begins as a subcutaneous infection which distinguishes it from cellulitis
• usually rapidly progressive over hours of pain and swelling of scrotum (vulval area in women) or perineum
• pain usually extends beyond the area of erythema
• fever, generalised weakness are often associated
• up to half of cases have subcutaneous air which may be palpated as crepitus
• as it progresses, sepsis / septicaemia develops and it may become foul smelling with areas of purpura and then black necrotic patches in the overlying skin

• usually a clinical diagnosis
• Xrays, ultrasound may show subcutaneous air
• CT scan may show source and extent of spread

• urgent Mx as per sepsis / septicaemia but with emergent surgical referral for potential debridement of necrotic tissue