Background: Immediate breast reconstruction is increasingly performed; however, there are concomitant concerns regarding its complications, especially surgical site infections（SSI）. The incidence rate of breast implant infection at our hospital was 5.69%（55/967 breasts）between January 2010 and August 2014. Preventive measures were taken and their effectiveness was evaluated.
　Methods: Immediate breast reconstruction with tissue expander（TE）insertion following mastectomy was performed on 1797 breasts between January 2010 and February 2018. Infection rates were compared between two groups, based on whether the surgery was done before or after the implementation of SSI preventive measures（September 2014）. The cases were further divided into those with or without SSI, and the correlation with various factors was examined.
　Results: The incidence rate of SSI after September 2014 was 2.65%（22/830 breasts）, which was significantly lower than the comparison group（p = 0.001）. There were no significant differences between the two groups in the analysis for risk factors of SSI.
　Conclusions: The infection rate of immediate breast reconstruction decreased from 5.69% to 2.65% after the implementation of preventive measures for SSI, suggesting that the measures were effective. The environment surrounding the treatment is constantly changing; thus, it is important to also update preventive measures.

　Keloids are intractable disorders in humans. An ideal experimental animal model that reproduces keloids has not been developed. Much of the evidence for current keloid treatments, therefore, is based on case report results. Current treatments that combine multiple treatment methods are associated with a high risk of recurrence, and standardized treatments are not yet established. A keloid animal model for evaluation is essential when developing new keloid therapeutics. In this study, human keloid tissues were selected and transplanted subcutaneously into two immunodeficient mice（nude mice and NOD / scid mice）. We found that the transplanted tissue survived for 11 weeks in NOD/scid mice. This mouse model may be useful for examining short-term therapeutic effects.

　Introduction: We investigated the relationship between the severity evaluation and outcome of cases of severe soft tissue infection experienced in our department.
　Methods: Between May 2018 and January 2021, 19 cases of severe soft tissue infections, such as subcutaneous abscess, cellulitis, gas gangrene, necrotizing fasciitis, requiring urgent surgical intervention in our department were analyzed retrospectively based on medical records.
　Results: Outcomes were 13 survivors, 4 deaths, 1 unknown, and 1 in hospital. Of the 19 cases, 3 cases were diagnosed with necrotizing fasciitis or gas gangrene by clinical diagnosis even though the Laboratory Risk Indicator for Necrotizing Fasciitis（LRINEC）score was less than 6. Since there was dissociation between the LRINEC score and clinical diagnosis, the surviving group and the dead group were compared, and a significant difference was found in the Cr, clinical diagnosis.
　Conclusion: If there is a dissociation between the LRINEC score and clinical diagnosis, the clinical diagnosis is emphasized, and treatment according to the diagnosis may lead to lifesaving of the patient.