Purpose: Pyomyositis of the thigh is a rare condition and there are few cases documented in the setting of urinary fistula, emphysematous cystitis, traumatic bladder rupture and previous pelvic surgery or radiotherapy. This is the first case report of pyomyositis secondary to complications of total cystectomy and bladder reconstruction. Methodology: A retrospective case report of a 69 year old male who presented with sepsis and three weeks of left thigh pain. He has a background of bladder cancer treated with total cystectomy and neo-bladder formation and chemoradiotherapy for urethral recurrence. He was reviewed for suspicion of a left thigh necrotising soft tissue infection and a CT demonstrated extensive subfascial and intramuscular gas throughout the left thigh and perineum. Results: The patient proceeded to the operating theatre for exploration and debridement. There were no signs of necrotising fasciitis, but copious intramuscular turbid fluid extending from the gluteal muscles. Closer review of the CT scan revealed gas locules between the neobladder and pubic symphysis. A contrast CT cystogram demonstrated a fistula tract from the neobladder. Upon return to theatre, this fluid appeared consistent with urine and was tested for creatinine levels which was 423 mmol/L compared to 91 mmol/L serum creatinine, suggesting contamination with urine. The neobladder leak was managed with long term catheterisation and output decreased as urine diverted through the urinary catheter. Conclusion: In cases of pyomyositis of the lower limb, it is important to consider pathology or previous surgery or radiation therapy in the pelvic region given the potential for communication between the pelvic cavity and thigh.