Necrotizing fasciitis is a type of soft tissue infection that destroys subcutaneous tissue. It is particularly dangerous for patients with chronic diseases and those who are bedridden while recuperating. Although necrotizing fasciitis is often caused by trauma or postoperative infection, in rare cases, it can be attributed to pressure injury (PI). The disease progression is very aggressive and can be lethal for patients who are bedridden or immunocompromised.This case report describes a 47-year-old man with a history of diabetes and hypertension who became bedridden after a sudden status decline caused by nephrotic syndrome. He gradually developed an infection and rare deterioration of a PI on his upper back. After radiologic evaluation with magnetic resonance imaging and computed tomography, surgical intervention was performed and necrotizing fasciitis was confirmed. In this case of necrotizing fasciitis derived from a PI on the upper back, the infected area spread to the periphery at a rapid rate. The infection spread over his back and across the T1-T9 levels.In this report, the authors describe the integrated system of the thoracolumbar fascia and the very aggressive spread of necrotizing fasciitis. Because of the anatomic structure of the back and the characteristics of this infection, only aggressive surgical debridement could prevent the spread of infection and reduce the systemic effects of the infection. Physicians should be aware of the possibility of PIs in bedridden patients and, in cases of exacerbation of the wound, consider rapid surgical intervention after prompt examination and diagnosis to reduce mortality.