Persistent Iliopsoas Abscess Due to Fistulizing Crohnʼs Disease: Can Biologic Agents Play a Role?

Abstract

Iliopsoas abscesses are a rare yet fatal complication of Crohn's Disease with an incidence of 0.4% to 4.3% and morality rate of almost 100% in untreated cases. Treatment currently relies on antibiotics and procedural intervention for refractory cases. We present an intriguing case of a persistent iliopsoas abscess resistant to antibiotics and percutaneous drainage, but responsive to combination of biologics induction therapy and surgery. A 20-year-old male with Crohn's Disease presented to the hospital with fevers, right-sided hip pain, and malaise. White blood cell count was 17.45 K/uL (ref: 4.0-10.80 K/uL), C-reactive protein 45 mg/L (ref: 0-5 mg/L), and sedimentation rate was 42 mm/hour (ref: 0-15 mm/hour). Contrast enhanced computed tomography (CT) revealed a 5 X 3 cm abscess along the medial aspect of the right iliopsoas muscle and incidental ipsilateral hydroureteronephrosis (Image 1). Patient underwent CT-guided right iliopsoas percutaneous drain placement. He was empirically started on ceftriaxone and metronidazole but fluid cultures grew Pseudomonas aeruginosa. He continued to remain febrile despite being switched to piperacillin-tazobactam and later, meropenem. Patient subsequently underwent exploratory laparotomy with ileocecectomy and primary anastomosis for 45 cm of diseased terminal ileum. He remained hemodynamically stable and was discharged. Four weeks post-operatively, he was started on combination infliximab and methotrexate induction therapy with good response. Repeat CT for surgical follow-up showed marked improvement in the right iliopsoas abscess (Image 2). Crohn's Disease is the most common cause of secondary iliopsoas abscesses. Terminal ileum disease can cause iliopsoas abscesses by direct extension of a sinus tract through the mesentery into the retroperitoneal space overlying the iliopsoas sheath. Hydroureteronephrosis and deep vein thrombosis may occur due to mass effect. Patients must be promptly started on broad-spectrum antibiotics targeting anaerobes and gram-negative bacilli. CT-guided percutaneous drainage is the procedure of choice, requiring surgical intervention only in refractory cases. Our patient remained febrile despite broad-spectrum antibiotics and percutaneous drainage, making him the ideal candidate for surgical resection in combination with starting biologic agents. The role of biologics in mitigating the progression of persistent iliopsoas abscesses in Crohn's Disease needs to be explored further.2097_A Figure 1. 5 x 3 cm iliopsoas abscess with ipsilateral hydroureteronephrosis2097_B Figure 2. Improvement in abscess with biologic therapy and surgery