JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
RADIOLOGY CASE OF THE MONTH Necrotizing Fasciitis Redux
Oliver Gentile, Jack Hua; Francisco Morales, MD, Enrique Palacios MD, FACR
A29-year-oldwomanpresented initially toour emergency departmentwith a left neck infection. Shewas given antibiotics for cellulitis to take as an outpatient. The patient came back after oneweek due to severeworsening of the symptoms (Figure 1). On admission, the patient underwent imaging of the neck with Ultrasound and ComputedTomography (CT) (Figure 2). Shewas then started on piperacillin/tazobactamand clindamycin and due to the continued clinical deterioration, the patient taken to surgery and was found to have an extensive diffuse inflammatory process, abscesses anddiffusemyositis of the submental and anterior aspect of the neck. Her wound cultures eventually became positive for B-hemolytic Group A Streptococcus. Several surgical teams decided to bring the patient to the operating room for irrigation, debridement, and resection of necrotic muscle, fascia, and skin. A modified Blair incision, with elevation of the subplatsymal flaps, revealed necrosis of the platysma extending to the subdermal subcutaneous fat and an abscess of the sternocleidomastoid muscle with necrotic involvement of the left mastoid tip extending to the tail of the left parotidgland.These areasweredebrided, irrigatedand coveredwithplaingauzewithbacitracin saline solution.
DISCUSSION
because the trunk and limbs do not have these attachments, there is a tendency for infection to spread. Edema can also occur secondary to venous and lymphatic spread. This spread can also cause thrombosis of blood vessels that leads to tissue ischemia and possible gangrene of subcutaneous fat and the dermis. Once the fascia breaks down, infection of the muscle leads to myositis, as occurred in our patient. Although rare, subcutaneous emphysema, known colloquially as gas gangrene, can also occur in the necrotizing tissue and is often caused by Clostridium species.
Necrotizing fasciitis is a relatively uncommon and potentially life-threatening soft tissue infection, with morbidity and mortality approaching 25-35%, even with optimal treatment. While necrotizing fasciitis can affect the dermis and epidermis, the majority of cases involve the deeper layers of adipose tissue, fascia, and muscle, making it difficult to differentiate from other, more benign skin pathologies. The degree of tissue destruction depends on the pathogen involved and its virulence factors. 1 Approximately 1000 cases are reported annually in the U.S. These necrotizing soft tissue infections (NSTIs) occur equally in men and women. They are more common in obese and immunocompromised individuals but may also occur in young otherwise healthy individuals. 2 The differential diagnosis for these patients includes abscesses and cellulitis; however, the most important step is a thorough and accurate history, as the definitive standard for diagnosing NSTI is timely operative exploration with a high index of clinical suspicion. 3, 4 Necrotizing fasciitis can be classified into three categories, with type 1 infections representing polymicrobial infections, type 2 involving Group A Streptococcus, typically streptococcus pyogenes, and type 3 representing gram negative marine organisms, most notably vibrio vulnificans. 1 Although necrotizing fasciitis typically affects the perineum and trunk, our case reflects its ability to affect the head and neck. Ultimately, the organism responsible for a given infection reflects the native flora. Most cases of necrotizing fasciitis occur due to trauma to skin that then seeds bacteria. Infection begins in the deep tissue, where bacteria can rapidly proliferate within viable tissue. Fibrous attachments between subcutaneous tissues and fascia limit spread to areas like the hands, feet, and scalp, but
Imaging may be used in determining the level of infection as well as the presence of gas; however, it is generally not
Figure 1: Anterior view of the submental and anterior aspect of the neck reveals diffuse soft tissue swelling and diffuse erythema.
J La State Med Soc VOL 169 SEPTEMBER/OCTOBER 2017 145
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