Dermatologic Manifestations of Necrotizing Fasciitis

Updated: Jun 06, 2022
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Necrotizing fasciitis is a severe, insidiously advancing, soft-tissue infection characterized by widespread fascial necrosis (see the image below). A number of bacteria in isolation or as a polymicrobial infection can cause this condition. [1] The organisms most closely linked to necrotizing fasciitis are group A beta-hemolytic streptococci, although the disease may also be caused by other bacteria or different streptococcal serotypes. In Texas from 2001-2002 and from 2009-2010, a rising incidence of necrotizing fasciitis of 5.9 versus 7.6 cases per 100,000 population has been documented, although hospital mortality (9.3%) was unchanged. [2] A nationwide French study identified 1537 patients with a median age of 60 years, with 23.7% dying. [3] Owing to an increasing litigious climate in many countries, necrotizing fasciitis has become the subject of numerous malpractice suites, [4] including from disability after successful outcomes from life-saving extensive surgery. [5, 6]

Left upper extremity shows necrotizing fascitis in Left upper extremity shows necrotizing fascitis in an individual who used illicit drugs. Cultures grew Streptococcus milleri and anaerobes (Prevotella species). Patient would grease, or lick, the needle before injection.

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Types of Necrotizing Fasciitis

Familiarity with necrotizing fasciitis may facilitate earlier diagnosis and initiation of appropriate therapy. This infection may occur as a complication of a variety of surgical procedures or medical conditions, including cardiac catheterization, [7] vein sclerotherapy, [8] and diagnostic laparoscopy, [9] among others. [10, 11, 12, 13, 14, 15] Necrotizing fasciitis can appear in a variety of sites after a number of encounters, including a stonefish sting, [16] following a shoulder sprain in a previously healthy person, [17] on a swollen breast, [18] and as a complication of acne appearing initially as lip cellulitis. [19]  It may occur as a bilateral necrotizing fasciitis with or without orbital involvement. [20]  Necrotizing fasciitis of the head and neck may may originate from an odontogenic infection and portends an unfavorable prognosis. [21]

Type I, or polymicrobial necrotizing fasciitis, usually occurs after trauma or surgery. This form may initially be mistaken for a simple wound cellulitis. However, severe pain and systemic toxicity reflect widespread tissue necrosis underlying apparently viable skin. This disease process may also be observed in association with urogenital or anogenital infections below). [22]

Type II, or group A streptococcal necrotizing fasciitis, is the so-called flesh-eating bacterial infection. [12]

Type III necrotizing fasciitis, or clostridial myonecrosis, is gas gangrene. This skeletal muscle infection may be associated with recent surgery or trauma.

Type IV can be designated as fungal necrotizing fasciitis. Since necrotizing fasciitis is rarely caused by or complicated by a fungus, the authors of this Medscape Reference article (Schwarz and Kapila) have designed it as type IV. In any case, early fungal smear and culture should be considered. [23] Candidal species may be etiologic, [24] possibly combined with a bacterial etiology such as Streptococcus pyogenes. [25]


Clinical Evaluation

In a study of 20 patients with necrotizing fasciitis with a median age was 52.5 years, the overall mortality rate was only 8.3%, attributed to early diagnosis and treatment. [26] Half had a comorbidity such as diabetes mellitus or congestive heart failure.

A study of 469 Malaysian necrotizing fasciitis patients reported that 59% were men, most patients were aged 30-79 years, and the majority had monomicrobial infections, with Streptococcus species (19%), Pseudomonas aeruginosa (13%), and Staphylococcus species (13%) being isolated. [27]

Patients with necrotizing fasciitis tend to present with erythema and supralesional vesiculation or bullae formation 2-3 days following constitutional symptoms of fever and chills. Serosanguineous fluid may drain from the affected area.

From a rapidly advancing erythema, painless ulcers may appear as the infection spreads along the fascial planes. A black necrotic eschar may be evident at the borders of the affected areas, and metastatic cutaneous plaques may occur.

Purpura with or without bullae formation, occasionally with a lack of cutaneous erythema and heat, may be found, but this does not preclude the diagnosis of necrotizing fasciitis. [28] Gas may be evident; this process may also be observed in the perineum in association with urogenital or anogenital infections, also known as Fournier gangrene. [29] This form of necrotizing fasciitis type I expands progressively and has a poor outcome, despite the commonest etiological event being minor trauma, with diabetes mellitus and obesity predisposing and most exhibiting a polymicrobial infection with sepsis. Special approaches have been suggested to treat Fournier gangrene in COVID-19–positive patients. [30]

Necrotizing fasciitis may develop after skin biopsy; at needle puncture sites in those use illicit drugs; and after episodes of frostbite, chronic venous leg ulcers, open bone fractures, insect bites, surgical wounds, and skin abscesses. It has been described resulting from a Serratia marcescens infection after a snake bite. [31] It has even been described affecting the perineum and genital region due to excessive masturbation in an otherwise healthy man with severe scrotal pain and swelling and frequent masturbation who had used soap as a lubricant, resulting in recurrent penile erythema and minor skin abrasions. [32]

See the images below.

Massive perineal ulceration with foul-smelling dis Massive perineal ulceration with foul-smelling discharge in a 60-year-old woman who had undergone postvaginal hysterectomy and repair of a rectal prolapse. Cultures revealed Escherichia coli and Bacteroides fragilis. The diagnosis was peroneal gangrene.
Necrotizing fascitis at a possible site of insulin Necrotizing fascitis at a possible site of insulin injection in the left upper part of the thigh in a 50-year-old obese woman with diabetes.

However, in many cases, no association with such factors can be made. Necrotizing fasciitis may also occur in the setting of diabetes mellitus, surgery, trauma, or infectious processes.

Necrotizing fasciitis causes thrombosis of fascial blood vessels, producing a true surgical emergency. Although thickening of the deep fasciae as a result of fluid accumulation and reactive hyperemia may be visualized using computed tomography and magnetic resonance imaging, these findings are not specific for necrotizing fasciitis. [33] Thus, although imaging studies can confirm the diagnosis and evaluate spread, they should not delay emergency surgical treatment.

In type II necrotizing fasciitis, the widespread tissue necrosis underlying the apparently viable skin can be demonstrated by passing a probe through the tissue. The condition may appear similar to a simple wound cellulitis; however, the severe pain and systemic toxicity reflect the widespread tissue necrosis underlying the apparently viable skin. When surgically confirmed necrotizing fasciitis cases were compared with 12 patients with superficial soft-tissue infection, the patients with necrotizing fasciitis were more likely to have skin areas of ischemia or necrosis, fluid-filled vesicles, and severe sepsis or septic shock. [34]

Gas usually is not evident in affected tissues in type II necrotizing fasciitis. Although the following features can occur with cellulitis, they may instead suggest necrotizing fasciitis:

  • Rapid progression

  • Poor therapeutic response

  • Blistering necrosis

  • Cyanosis

  • Extreme local tenderness

  • High temperature

  • Tachycardia

  • Hypotension

  • Altered level of consciousness

Pediatric cases

In a pediatric necrotizing fasciitis series, clinical features began 1 week after the initiating event, beginning with edema and induration, which was followed in 24-48 hours by erythema or a violaceous discoloration. [35] Pain and, occasionally, crepitation, was also noted early. Crepitation indicates the presence of gas produced by aerobic and anaerobic bacteria and is highly suggestive of the diagnosis of necrotizing fasciitis; this finding is often present in patients with diabetes and in those with nonclostridial anaerobic infections. In a series of 39 pediatric cases, the most common initiating factor in 13 of them was varicella. [36]


Differential Diagnosis

Limb- and life-threatening hand and foot infections, including necrotizing fasciitis, in diabetic patients account for substantial morbidity and mortality. [37] Of 56 patients in 1 series, 17 (30.36%) had necrotizing cellulitis, 12 (21.43%) had wet gangrene, 9 (16.07%) had acute extensive osteomyelitis, 5 (8.93%) had dry gangrene, 5 (8.93%) had gas gangrene, 4 (7.14%) had necrotizing fasciitis, and 4 (7.14%) had diffuse hand infections. In diagnosing necrotizing fasciitis, computed tomography is better than plain radiography. Nevertheless, clinical suspicion suggests use of early surgical consultation to facilitate diagnosis. [38]

Other conditions that should be considered when evaluating a patient with suspected necrotizing fasciitis include the following: