Discussion

Necrotizing fasciitis

Necrotizing fasciitis (NF) is characterized by spreading necrosis of the subcutaneous tissue and fascia that is associated with systemic toxicity and extension along fascial planes. NF of the breast is rare, with a limited number of cases reported to date. More commonly, necrotizing soft-tissue infections are described to be found on the extremities, trunk, and perineum. Konik et al, Yaji et al, Fayman et al, Ward et al, and Shah et al reported the first cases of breast NF as early as 2001.

The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC), first described by Wong et al, is a tool based on six common serum parameters that can be used upon patient presentation to determine the risk for NF. The six serum parameters include C-reactive protein, total white cell count, hemoglobin, serum sodium, creatinine, and glucose. A LRINEC score of 6 or greater suggests a higher risk of NF, with a score of 8 or higher having a positive predictive value of 93.4% for necrotizing soft-tissue infection indicating further work-up or emergent operative debridement. The patient presented in this case report was found to have a LRINEC score of 11 points, indicating a high risk for NF. Notably, high clinical suspicion for necrotizing soft-tissue infection obviates the usefulness of the LRINEC score, with recommendations to instead take the patient for immediate operative debridement.

Despite an initial LRINEC score of 11 points, there was a delay in the management of the patient due to initial misdiagnosis. It was not until day two at the hospital that formal imaging was performed, which was obtained for workup of abdominal pain rather than for evaluation of the breast abscess. As discussed previously, following a bedside ultrasound of the breast, the surgery team did not suspect NF but rather an infected cyst versus an abscess. According to previous literature, NF of the breast can often be misdiagnosed as mastitis, cellulitis, inflammatory breast cancer, or abscess, as in this case. Misdiagnosis of this patient resulted in a delay in operative management for NF. Previously published case reports of breast NF showed that early debridement, along with mastectomy, was the primary management, along with antibiotics. Mastectomy was the most common treatment among 18 recent cases in a literature review, while the patient presented here underwent two surgical debridements not requiring mastectomy.

Bedside ultrasound as an adjunct in the workup for necrotizing soft-tissue infection is limited due to lack of resolution of deeper structures, though soft-tissue gas should still be identifiable on ultrasound. Nonspecific findings of NF include an echogenic layer of gas above the deep fascia with posterior dirty acoustic shadowing. In addition, hyperechogenicity of the overlying fat can resemble a cobblestone appearance representing subcutaneous edema; however, these findings can also be seen in cellulitis or anasarca. More specific sonographic signs of NF include overall fascia thickening with abnormal fluid collections along fascial planes.

With respect to our patient and her comorbidities, she was at greater risk for developing a necrotizing soft-tissue infection, as she had uncontrolled diabetes mellitus with significantly elevated blood glucose on admission and nonadherence to a home diabetes regimen. The patient reported that she had noticed an insect bite to the breast one week prior to admission. An insect bite as an inciting event for the development of NF is rare in the literature, as most cases report trauma to the breast as an etiology (e.g., needle core biopsy, mastectomy, breast tumors, etc.). Other risk factors, which are not applicable to our present case, include an immunocompromised state, underlying malignancy, current IV drug use, chronic renal failure, and peripheral vascular disease. Of note, age is not a risk factor for NF, as it can occur at any age despite it being found predominantly in the elderly population.

Once diagnosed, management of NF of the breast includes prompt surgical debridement in combination with broad-spectrum antibiotics. Staged debridements, as opposed to immediate mastectomy, have become the new standard of practice, however, in most cases of primary NF of the breast, mastectomy is required to achieve adequate source control. The antibiotic regimen for NF of the breast is broad but usually is narrowed based on the organisms isolated from wound cultures. The infection can be further classified based on the organisms found. Type 1 is considered polymicrobial and can be composed of Gram-positive, Gram-negative, and anaerobes, whereas type 2 is usually with group A Streptococcus or other beta-hemolytic Streptococci in combination with other infectious pathogens. Type 2 infections are usually seen with diabetic patients or those with other comorbidities, although our patient, despite being a diabetic, was found to have a wound colonized with Proteus, which required a broad-spectrum regimen prior to being narrowed on discharge.

The patient’s new-onset AFib that occurred postdebridement was likely secondary to sepsis and undergoing surgery. The patient’s body was overall stressed by her breast NF infection as well as surgical debridement of the wound. AFib is the most common arrhythmia seen in patients with sepsis, and hospitalized patients with sepsis have up to a sixfold higher risk of developing atrial fibrillation. While other cases of breast NF in the literature to date have not reported AFib as a complication, one case reported that a patient had a myocardial infarction postoperatively as a result of sepsis and multiorgan failure. Further research and literature reviews are needed to report whether or not cardiac complications such as the ones above may be at higher risk with breast NF.

Learning points

1. This case of NF of the breast is rare, with most reports of NF affecting the extremities, abdominal wall, or near the anus or vaginal canal. It is infrequently found within the breast, and most cases present following traumatic events or surgical interventions, such as with resection.
2. The initial presentation of necrotizing soft-tissue infections varies from a minor infection of the soft tissues to severe forms that can present with septic shock or multiorgan system dysfunction and failure. Therefore, early identification of NF is paramount for proper treatment.
3. This case emphasizes the importance of careful attention to clinical presentation, imaging, patient medical history, and surgical management in recognizing and treating this rare diagnosis of NF of the breast.

References

View the original case report for a complete list of references.

Our appreciation is extended to Drs. Rachel Jane Klapper, Benjamin Joseph Michael Horn, Benedict Amalraj, Maamannan Venkataraj, Mohammad Abdurrehman Sheikh, Kiran Malikayil, and Jeffrey Wooliscroft, Louisiana State University Health Sciences Center – Shreveport, Shreveport, LA, U.S.; and Dominika Pullmann, New York Medical College – Metropolitan Hospital Center in New York, for contributing this case. Case was originally published in BJR|case reports.