Necrotising soft tissue infection of the lower limb due to a perforated caecal carcinoma: a case report

Extra-abdominal manifestations of retroperitoneal infection: a case of popliteal sinus secondary to duodenal ulcer

Retroperitoneal abscesses can be gastrointestinal, urological or vascular in origin, and can spread via the retrofascial compartment through the psoas muscle to the lower limb. We describe the case of a 73-year-old woman with right knee pain for three weeks, a cellulitic right thigh and cholestatic liver function tests. A purulent sinus developed in the popliteal fossa and computed tomography of the abdomen revealed a right-sided retroperitoneal collection with gas, extending to the right pelvis and inguinal region. The popliteal fossa sinus and retroperitoneal collection were identified as a single pathology through computed tomography, magnetic resonance imaging and culture of identical organisms. At laparotomy, perforated duodenal ulcer disease was identified as the cause of the retroperitoneal abscess. Clinicians should seek to exclude retroperitoneal sources of infection in cases of lower leg infection, including perforated duodenal ulcer, caecal adenocarcinoma and appendicitis.

Perforated caecal carcinoma masquerading as lower limb necrotising fasciitis: lessons learnt

A 69-year-old man was admitted with non-resolving right leg cellulitis. Subsequent skin changes over the calf and discharging pus suggested necrotising fasciitis. After several wound debridements of the leg and imaging, the patient was found to have an iliopsoas abscess due to a metastatic perforated caecal tumour extending along the medial thigh to the calf. No micro-organisms indicative of typical necrotising fasciitis were isolated from the wound. The patient had an ileocaecal resection, and his leg was reconstructed with a split thickness skin graft. He continues to do well postoperatively. This case highlights key lessons when dealing with an unusual presentation leading to challenges in diagnosis such as: (1) the need for good interspecialty liaison, (2) prompt senior review and plan, and (3) 'thinking outside the box' when faced with a diagnostic challenge.

Caecal cancer presenting as leg erythema and a lung opacity

Necrotising infection of the lower limb is a rare presentation for colorectal malignancy. We report a case of a perforated caecal adenocarcinoma presenting with right leg erythema, pain and swelling in the presence of a right lower lobe lung opacity. Following initial debridement and washout, CT imaging demonstrated a thickened terminal ileum, caecum and appendix, in keeping with primary malignancy. This fed the right-sided lower limb sepsis tracking down from the medial aspect of the psoas muscle to give rise to the multiloculated collection seen in the adductor compartment. The lung lesion measured 16 mm and was metastatic. The patient was successfully managed with a subtotal colectomy and an end ileostomy. The biopsy confirmed an adenocarcinoma (T4N1M1). We highlight the importance of perforated colonic carcinoma as a leading differential for lower limb abscesses. Suspicions should be raised further if accompanied by rounded opacifications on plain film radiography of the lungs.