Necrotizing myositis is a severe and very rare streptococcal soft tissue infection involving the superficial fascia and muscle. Its clinical symptoms are nonspecific until the appearance of a fulminant clinical course with soft tissue destruction and septic shock. A high mortality and morbidity rate has been reported in the few cases over the last century. Despite several attempts to better define the different entities causing this necrotizing soft tissue infection, no clear treatment has been outlined. We present the case of a 47-year-old woman who had an acute necrotizing myositis after a stab wound. The diagnosis of necrotizing myositis was only established after surgical treatment with a pathology report. We reviewed the literature to highlight the clinical difficulty of a preoperative diagnosis and surgical treatment.