Breast cancer is one of the most common cancers in women, with an incidence rate of 89.7 per 100,000 women in Western Europe. High survival rates have been achieved in these countries [
1], but these high survival rates can be accompanied by other problems. BCRL is one of the most common complications after breast cancer treatment. The overall incidence of BCRL has been reported as 26% after mastectomy, and axillary lymph node dissection with axillary radiotherapy significantly increases the risk of BCRL (relative risk, 6.9) [
4,
5]. As lymphedema provides an ideal environment for bacterial growth, probably because of the decreased lymphatic flow and impaired elimination of phagocytosed bacteria, soft tissue infection is quite common as a complication among patients with BCRL [
6]. Most of the causative pathogens are
Staphylococci or
Streptococci, and infection is often treated without serious progression. However, streptococcal infections occasionally develop into STSS. The development of STSS significantly increases the risk of mortality, which may exceed 50% [
7]. Criteria for the diagnosis of STSS were established by the Centers for Disease Control and Prevention (CDC) in 2010 (Table
2) [
8]. Most cases of STSS are caused by GAS, but cases caused by SDSE belonging to Lancefield serogroup C or G have recently been reported. In 2011, a Japanese surveillance study reported the involvement of GAS in 78% of STSS (76 cases), group G streptococci in 21% (22 cases, all involving SDSE), and group C streptococci in less than 2% (two cases, one with SDSE, and the other with
Streptococcus constellatus
subspecies
pharyngis) [
9]. Although GAS can affect even the healthy, SDSE mainly affects elderly individuals with chronic diseases, such as diabetes mellitus, cardiovascular disease, malignancy, and immunosuppression. In particular, breakdown of the skin was noted in 30 to 60% of cases [
2], while the most common clinical manifestation of invasive SDSE infection is cellulitis (41%) [
2]. The mortality rate from SDSE bacteremia is 15 to 18%, which is comparable to that for GAS bacteremia. SDSE infection by itself is considered less severe than GAS bacteremia, but the effects of patient characteristics, such as age and underlying diseases, may increase the infection severity [
2].
Table 2
Clinical criteria for the diagnosis of streptococcal toxic-shock syndrome
1. Hypotension | |
2. Multi-organ involvement characterized by two or more of the following: | |
Renal impairment | |
Coagulopathy | |
Liver involvement | |
Acute respiratory distress syndrome | |
A generalized erythematous macular rash that may desquamate | |
Soft-tissue necrosis, including necrotizing fasciitis or myositis and gangrene | |
Isolation of Streptococcus from | |
Non-sterile site ⇒ Probable | |
Normally sterile site ⇒ Confirmed | |
In our case, the patient had undergone left mastectomy and axial lymph node dissection with additional chemotherapy and radiotherapy following hormone therapy. Under such aggressive treatment, no sign of recurrence was seen for more than 2 years postoperatively, despite advanced lymph node metastasis. However, mastectomy with axial dissection and radiotherapy induced BCRL. This elderly woman with BCRL was at high risk of invasive SDSE infection and eventually developed STSS induced by SDSE. The clinical course, which progressed rapidly (within 24 hours) and emerged in the soft tissue, was typical of STSS [
7]. The route of transmission of the pathogen into the deep soft tissue was uncertain, but the edematous subcutaneous tissue might have provided a suitable environment for exponential bacterial growth. She presented signs of septic shock, requiring noradrenaline for 4 days in our ICU. In addition, her confused mental state, soft tissue infection following DIC with high inflammatory status (CRP 23.8 mg/dL; procalcitonin 8.37 ng/mL) and extreme leukopenia (900/μL) all suggested severe infection and toxicity. Thrombocytopenia with elevation of FDP also remained until day 4, despite appropriate DIC therapy (Fig.
2). Lastly, SDSE was isolated from the blood, and STSS was confirmed based on the CDC criteria (Table
2), with DIC, soft tissue infection, and generalized erythematous macular rash. SDSE is not as toxic as GAS, and no vital organ dysfunction developed, such as respiratory failure, liver involvement, or renal impairment. These factors were considered the main reasons why our patient survived her case of STSS. This report highlights the risk of life-threatening infection developing among survivors of malignancy. Therefore, invasive streptococcal infection should be taken into account as a risk factor after breast cancer treatment. Ageing and advances in medicine have created the need to address such cases.