Necrotising Myofasciitis of the Lower Limb Secondary to Extra-Peritoneal Rectal Perforation.

Necrotising fasciitis (NF) is a severe and life-threatening soft tissue infection that often requires extensive debridement and reconstruction. Isolated extra-peritoneal rectal perforations due to trauma, cancer, inflammatory bowel pathology or iatrogenically induced can rarely cause necrotising fasciitis beyond the perineum. Given its rarity, there is a high threshold of suspicion which often leads to late recognition and poor outcome. We present a case of necrotising myofasciitis of the right lower limb following occult rectal perforation sustained during elective flexible sigmoidoscopy, and augment this case report with a literature review to guide diagnostics, intervention, and recovery. Therefore, the aim of this work was to review, compile, analyse, and present clinical details to identify masquerading presentations and determine the optimal treatment regimen. A search of PubMed, Scopus, Ovid, MEDLINE, EMBASE, CINAHL Plus, AMED, Web of Science (Science Citation Index), and Google Scholar was supplemented by hand searching. Data extracted included demographics, patient management, and outcome. Of 104 citations identified by a systematic literature search, eight case reports of eight subjects with necrotising fasciitis of the lower limb secondary to rectal perforation met the criteria for analysis. The most common treatment modality was surgical debridement in all cases and bilateral above knee amputation in one case, disarticulation of the lower limb was the treatment in this case we report. Furthermore, faecal diversion by the formation of de-functioning colostomy was performed in the same setting for four (50%) of the patients and appeared to increase survival. Overall 45 days mean (S.E.) disease-specific survival was found to be 32.8 (7.0) days. There is an insufficient number of cases reported to date to confer a significant survival advantage between having a defunctioning colostomy in the same setting as the debridement as opposed to having it at a later setting or not having it at all (Mantel-Cox p=0.1). In summary, a review of all the cases in the literature suggests that NF of lower limbs can be an atypical presentation of rectal cancer, pathology, and/or trauma. We report a case of unilateral lower limb NF secondary to rectal perforation in a non-cancer patient, likely due to flexible sigmoidoscopy. Due to the small number of patients, it is inherently difficult to draw firm conclusions however multi-modality management appears to be more effective, with meticulous debridement, defunctioning of the bowel and downstaging radiotherapy if required. We recommend a UK-wide, national database/registry for NF that will help gather data and formulate more standardised management guidelines.