Necrotizing fasciitis of the thigh: An unexpected route to discover an infected colonic cancer

INTRODUCTION: Necrotizing fasciitis (NF) is a rare but potentially fatal soft tissue infection characterized by its aggressive nature. This case report highlights a unique and atypical presentation of NF associated with colorectal cancer. CASE PRESENTATION: A 76-year-old male with no significant medical history presented with left knee pain and rapidly progressing septic shock. Clinical examination revealed skin necrosis, inflammation, and swelling in the left thigh and inguinal region. Laboratory investigations showed leukocytosis and elevated C-reactive protein levels. Computed tomography angiography revealed fluid and gas tracking along fascial planes in the left thigh. Surgical intervention revealed NF in the thigh and abdominal wall, with the underlying cause being a perforated sigmoid colon cancer. CONCLUSION: Recognizing the polymorphic clinical manifestations of NF and its potential association with underlying abdominal pathology can aid in early diagnosis and improve patient outcomes. This report serves as a reminder of the life-threatening nature of NF and the necessity for rapid and comprehensive management.