Not your usual hip pain: necrotising fasciitis secondary to sigmoid perforation

Abstract

Necrotising fasciitis (NF) resulting from sigmoid perforation is rare, but none the less remains life threatening. Early surgical intervention and empiric broad-spectrum antibiotic remains the standard of care. A 65-year-old man with history of stage 4 rectal cancer presented with bilateral hip pain. An X-ray of the hip and pelvis to rule out fracture revealed abnormal gas pattern overlying the right hip. CT imaging revealed distal sigmoid perforation with air extending from the pelvis to posterior aspect of the right hip and thigh. Aggressive surgical intervention and antibiotic initiation was associated with successful outcomes in our patient. Although less common, sigmoid perforation leading to NF in posterior thigh is a reminder of a potentially lethal complication.

Background

Stage 4 rectal cancer has a 5-year survival rate of about 13%.¹Necrotising fasciitis (NF) of the lower limbs as a complication of sigmoid perforation in setting of rectal carcinoma is rare with only few case reports describing it in the literature. NF is usually divided into two microbiological categories: monomicrobial and polymicrobial. NF unrelated to its aetiology is associated with grave outcomes if not diagnosed and treated aggressively. Presence of gas in the soft tissues remains one of the hallmarks of this condition, with CT being one of the best initial imaging modalities. Combined mortality of stage 4 rectal carcinoma and NF remains extremely high, requiring clinicians to act aggressively even with low index of suspicion.

Case presentation

A 65-year-old man with medical history of hepatitis C, chronic left lower extremity deep vein thrombosis (DVT), stage 4 rectal cancer with metastasis to liver status post lower anterior resection on chemotherapy presented to the emergency department with bilateral hip pain with pain in right more than the left for 5 days prior to his admission. He also had chronic constipation over the past 3 months. On arrival his vitals his temperature 98.1°F, heart rate 111/min, respiratory rate 20/min, blood pressure 154/94 mm Hg and pulse oximetry 97%. Physical examination revealed voluntary guarding on palpation of the stomach, limited range of motion of the right hip and chronic left lower extremity swelling. Crepitus was absent on palpation of lower extremities. Laboratory work up showed white cell count 9.9×10⁹/L, platelet 0.92×10⁹/L, creatinine 1.1 mg/dL, aspartate aminotransferase 11 IU/mL, alanine aminotransferase 5 IU/mL and albumin 22 g/L. Patient was started on empirical broad-spectrum antibiotics.

Investigations

An X-ray of the right hip joint showed abnormal gas in the tissues overlying the superolateral right hip (figure 1). CT abdomen and pelvis and right lower extremity showed abnormal gas in the posterior aspect of the right thigh extending from the extraluminal gas surrounding the distal rectosigmoid colon and a sigmoid perforation (figures 2–4).

Figure 1.

X-ray showing presence of abnormal gas pattern in soft tissues over the right hip.

Figure 2.

CT abdomen and pelvis axial view arrow showing sigmoid perforation and stool in the pelvis.

Figure 3.

CT axial of the right hip arrow showing abnormal gas pattern in the posterior hip.

Figure 4.

CT right femur coronal view arrow showing abnormal gas pattern.

Differential diagnosis

The provisional diagnosis based on history and physical examination was NF, DVT and cellulitis. Subsequent venous duplex scans were negative for DVT. However, lack of superficial redness and presence of air on radiographs made the diagnosis of NF more probable.

Treatment

General surgery was consulted, and patient was taken for emergent exploratory laparotomy and repair of sigmoid perforation. Exploratory laparotomy revealed perforation at the site of rectosigmoid anastomosis secondary to chronic constipation associated with narcotic use. Large amount of stool was noticed in the pelvis and a proximal end sigmoid colostomy was performed along with surgical incision and drainage with debridement of the right posterior thigh abscess. Cultures from the wound site and blood were positive for Bacteroides fragilis.

Outcome and follow-up

He underwent repeat incision and drainage along with debridement on postoperative day 11. He was subsequently discharged on postoperative day 26 with no further complications.

Discussion

Our case is a part of few limited case reports currently present in the literature that describes NF developing in the lower extremities arising as a result of perforation in the distal colon or rectum. For our patient the aetiology was sigmoid perforation arising secondary to chronic constipation from narcotics. Our patient was fortunate to have a complete recovery, however most of the patients developing NF on the background of colorectal cancer and chemotherapy decompensate early during their course of admission.^2–7 Rectal perforation leading to NF of the thigh has been explained by entry of faecal matter through femoral sheath, femoral canal, psoas sheath, sciatic notch and obturator foramen.⁸

Clinical presentation usually consists of pain, swelling and fever on history and tenderness, erythema of the involved site on physical examination. Presence of crepitus, skin necrosis, bullae and sensory deficits over the involved area are supportive to diagnosis, however their presence are typically seen later in the course or may be indicative of a rapidly developing fulminant infection.⁹ Pain over the involved site is typically out of proportion during the early stages of illness making early diagnosis of NF challenging.¹⁰

NF can be classified according to microbiological subtype: (a) Type I: polymicrobial which represents presence of anaerobic and aerobic flora. Most common anaerobic flora encountered Bacteroides, Peptostreptococcus, Clostridium, Enterobacteriaceae family and anaerobic streptococci. (b) Type II: monomicrobial most commonly caused by group A streptococcus and clostridium. Irrespective of the source early empirical antibiotic therapy and surgical debridement remains the mainstay treatment of NF. It has an overall mortality of 50%–70%.¹¹

In conclusion, early diagnosis and multimodal approach is key to superior outcomes. Close collaboration between the emergency department physicians, colorectal surgeons, oncologist and infectious disease specialist remained a pivotal point in our patient’s management.

Learning points.

• Necrotising fasciitis is the infection of the fascia and soft tissues.

• Empirical antibiotic therapy and surgical debridement remains the cornerstones of therapy.

• CT scan is the best initial modality to reveal presence of subcutaneous emphysema, fluid collections and thickening fascia.