CASE

A 14-year-old male presents with right thigh redness and pain. It’s a busy afternoon and you think to yourself, “This will be a quick and easy disposition. The patient probably has cellulitis.”

He reports one week of worsening erythema and pain to his right anterior groin. Last evening, he was able to drain a small amount of white to green-tinged material from a small “pimple” that had formed along the medial aspect of his thigh. He denies fevers, reporting a temperature max of 100.1 Fahrenheit. His pain, which localizes to the right anterior thigh, has worsened over the last three days, but he states it is tolerable and has never been severe. He has otherwise felt well, denying chills, fatigue, chest pain, abdominal pain, dysuria, or hematuria. All vaccinations are up to date. He has no past medical or surgical history. He has poor hygiene, showering only once per week.

On exam, the patient is afebrile, but tachycardic with a heart rate of 164 beats per minute. His blood pressure is normal. He looks comfortable, with an unremarkable exam until you expose his right thigh. You note a large area of erythema to his anterior right thigh which tracks toward the groin (Figure 1). There is no clear involvement of the perineum or scrotum. You feel crepitus as you palpate the area of erythema.

A bedside ultrasound shows a fluid collection involving the medial right thigh near the inguinal canal as well as gas within the soft tissues of the right thigh. A comprehensive ultrasound confirms these findings (Figure 2). Ultrasound of the scrotum is normal.

You administer intravenous fluids and begin broad spectrum antibiotics, while awaiting surgical consultation. Shortly thereafter, the patient is whisked away to the operating room, where surgical incision reveals a large amount of malodorous necrotic appearing fascia consistent with a necrotizing soft tissue infection.

DIAGNOSIS

Necrotizing fasciitis

DISCUSSION

Necrotizing soft tissue infections are rare in the pediatric population, with limited data suggesting 0.08 cases per 100,000 cases [1], but are a critical “can’t miss” diagnosis in the emergency department.

These infections are most commonly seen in diabetic or immunosuppressed adults, and most often involve the lower extremities. If the infection involves the perineum or genital region, the term Fournier’s Gangrene is used. Genital involvement in the pediatric population is rare, with most infections having primarily truncal involvement. When genital lesions are found, small case series suggest that approximately 50% of cases are related to instrumentation or surgery to the genital area preceding infection, while the remainder of cases are secondary to infectious extension from neighboring lesions (in the abdomen or thigh). [2] That being said, necrotizing infections can occur in healthy individuals with no past medical history or clear portal of entry to allow for translocation of bacteria. [3]

The diagnosis of necrotizing soft tissue infection is ultimately made upon visual examination of necrotic appearing tissue in the operating room. [4] A general paucity of cutaneous findings early in disease progression can make diagnosis difficult, [5] and it is common for early disease to be written off as a simple cellulitis. But vesiculation, ecchymosis, crepitus, anesthesia and purple discoloration, a hallmark of cutaneous necrosis, can be suggestive of advanced disease. [2] Imaging studies, while not necessary to diagnose necrotizing infections, can aid in decision making. CT scan remains the imaging modality of choice, however in the pediatric population, ultrasound can be a useful tool to show fluid and gas collections tracking along fascial planes without exposing children to excess radiation. [3]

Lab work, if obtained, may show a leukocytosis with left shift, acidosis, coagulopathy, and elevation of inflammatory markers. However, these tests are not particularly specific for diagnosing a necrotizing soft tissue infection. It is important to obtain blood cultures if a necrotizing soft tissue infection is on the differential. [3]

Along with early surgical debridement for suspected cases, prompt initiation of antibiotics plays a critical role in treating these infections. Both polymicrobial (involvement of at least one anaerobic species, commonly Bacterioides, Clostridium, or Peptosteptococcus, along with Enterobacteriaceae, and one or more facultative anaerobic streptococci organisms [3]) and monomicrobial (usually caused by group A Streptococcus) have been described in the literature. Antibiotic therapy should cover all possible causative organisms. For that reason, antibiotics should have broad activity against gram-positive, gram-negative, and anaerobic bacteria. Commonly used antibiotic regimens include a carbapenem (impipenem, meropenem, ertapenem) or beta-lactam-beta-lactamase inhibitor (Zosyn, Unasyn), along with an agent to cover MRSA (vancomycin, daptomycin), and clindamycin, as it inhibits the synthesis of bacterial toxin. [3]

CASE RESOLUTION:

During admission, the patient returns to the operating room three times for washout, debridement, and wound vac placement. He is treated with vancomycin, clindamycin, and unasyn for 11 days, then is discharged home with the wound vac and an additional nine days of Augmentin.

TAKE-AWAYS

• Necrotizing soft tissue infections are rare in the pediatric population, but potentially life threatening

• Patients presenting with necrotizing soft tissue infections are often otherwise healthy, although diabetes and immunosuppression increase your risk

• Diagnosis of necrotizing soft tissue infections is made clinically upon evaluation of necrotic tissue in the operating room. Imaging studies showing gas and fluid collections can help increase your suspicion in the emergency department

• Early surgical debridement, broad spectrum antibiotics, and supportive care are the hallmarks of management

Author: Jared Supple, MD is a third year emergency medicine resident at Brown University/Rhode Island Hospital.

Faculty Reviewer: Dr. Palmisciano is a pediatric emergency medicine physician at Hasbro Children’s Hospital.

REFERENCES

1. Laupland KB, Davies HD, Low DE, Schwartz B, Green K, McGeer A. Invasive group A streptococcal disease in children and association with varicella-zoster virus infection. Ontario Group A Streptococcal Study Group. Pediatrics. 2000;105(5):E60. doi:10.1542/peds.105.5.e60

2.  Fustes-Morales A., Gutierrez-Castrellon P., Duran-Mckinster C., et al: Necrotizing fasciitis: report of 39 pediatric cases. Arch Dermatol 2002; 138: pp. 893-899 

3. Stevens, Dennis, and Larry Baddour. “Necrotizing Soft Tissue Infections.” Up To Date, Wolters Kluwer, 6 June 2019, https://www.uptodate.com/contents/necrotizing-soft-tissue-infections?seach=necfasciitis&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#h24 

4. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America

5. Legbo J.N., and Shehu B.B.: Necrotising fasciitis: experience with 32 children. Ann Trop Paediatr 2005; 25: pp. 183-189