the association between crohn s disease ( cd ) and colorectal cancer is well established . we report a case of a 40-year - old cd patient who developed an anal adenocarcinoma within a long - standing perianal fistulous tract and review the available literature . a 40-year - old male patient with ileocolonic cd and perianal fistulising lesions , diagnosed 23 years ago , was referred to our institution for a new finding of soft tissue within a perianal fistula . his past medical history included loop sigmoidostomy and seton insertion 3 years ago for control of his perianal disease . three months later , due to ileus caused by terminal ileitis , he underwent emergency right colectomy . at the same time , the loop sigmoidostomy was converted to end colostomy with closure of the peripheral stump ; since , the perianal disease was still uncontrollable . at this time , taking into account the benign nature of the disease , as well as patient s age , it was decided to give to the patient a second chance to keep his sphincter mechanism rather than to perform an abdominoperineal resection . the patient had received in the past , either in conjunction or consequently , corticosteroids , antibiotics ( metronidazole , ciprofloxacin ) , immunosuppressants ( azathioprine , methotrexate ) and anti - tnf agents ( infliximab ) for the control of the frequent flare - ups . on referral physical examination revealed mild perianal inflammation with muco - purulent discharge from two sore - like fistulous orifices , located at 7 and 11 oclock in supine position ( fig . 1 ) . pelvic magnetic resonance imaging ( mri ) demonstrated pathological tissue development within one fistulous tract ( fig . the rectosigmoidoscopy depicted mild lesions compatible with moderately active cd , without any other sign of obvious malignancy . mucosal biopsies were obtained from the lesions and the underlying fistulous tracts ; granulomatous tissue infiltrated by mucus - producing adenocarcinoma was found on pathology . thus , the patient underwent abdominoperineal resection , where a 37  cm segment of colon with the mesorectum , anal canal of 7  cm and the corresponding overlying soft tissue of the perineum was resected . on histopathology , a t4n1 moderately / poorly differentiated mucinous adenocarcinoma was detected ( fig . 3 ) . according to the referrer , his last physical examination , six months prior to admission , was unremarkable . unfortunately , three months postoperatively the patient developed multiple bone metastases and he is currently receiving chemotherapy . the development of carcinoma within a chronic perianal fistula is a rare complication of cd , first reported by lightdale et al . in 1975 . has reported 65 cases with anorectal cancer associated with perianal fistulae in patients with cd   with an estimated incidence of 0.30.7% . the pathogenesis has not yet been fully elucidated ; traube at al . suggested that the environment of constant mucosal regeneration occurring within a fistula may cause dysplastic changes , which may ultimately lead to adenocarcinoma . on the contrary , church et al . supported that a fistula formation may be a result of the cancer itself . in the present case it has been suggested that immunosuppressants and anti - tnf agents may contribute to the malignant transformation . in a recent article , osterman et al . supported that patients treated with combination of adalimumab and immunomodulators were more likely to develop cancer compared both to general population and patients with adalimumab monotherapy . this plausible pathogenetic mechanism may hold true in the present case , where the patient had been treated with anti - tnf and immunomodulators for approximately ten years prior to the diagnosis of cancer . patients with long - standing cd , diagnosed before thirty years of age and with faecal diversion are at greater risk for the development of carcinoma arising in association with a perianal fistula . unfortunately , the majority of these patients have poor prognosis due to the advanced disease stage at diagnosis . similarities between benign deterioration of the perianal symptoms and de novo development of cancer , as well as the lack of a high degree of suspicion for this rare complication may be responsible for the delay of diagnosis . furthermore , the exacerbation of the symptoms makes physical examination or colonoscopy cumbersome to occur . a complex , long - standing fistula requires thorough examination of the rectum and the perianal area under anaesthesia followed by biopsies and/or curettage of the fistulous tracts . it follows , those patients with chronic perianal fistulising cd should be kept under a regular and careful surveillance . ogawa et al . have suggested that a patient should undergo surveillance for carcinoma after seven years of perianal disease . the gold standard treatment of fistulae - associated anal adenocarcinoma in patients with cd is abdominoperineal resection . in a recent article , gaertner et al . reported that all patients with perianal adenocarcinoma who had undergone neoadjuvant chemoradiation therapy followed by abdominoperineal resection had a complete response . the potential benefits of this kind of therapy have not yet been established ; and therefore , in our patient we proceeded only to surgical treatment . clinicians who manage patients with long - standing perianal cd should maintain high level of suspicion for adenocarcinoma development on the setting of perianal fistulising cd . a chronic , complex fistulous disease may conceal a tumour and the examination under anaesthesia with biopsies and/or curettage of the fistulous tracts may be warranted . therefore , all patients suffering from chronic perianal cd should be kept under regular surveillance . all authors declare that there is no financial arrangement or other relationship that could be construed as a conflict of interest . papaconstantinou i. conceived of the study , carried out its design and the critical revision for important intellectual content and had the overall responsibility of the manuscript . mantzos s.d . carried out the design , the collection , analysis and interpretation of the data and drafted the manuscript . kondi - pafiti a. provided some of the data and participated in the critical revision . koutroubakis i. conceived of the study , participated in the design and carried out the critical revision . written informed consent was obtained from the patient for publication of this case report and accompanying images . a copy of the written consent is available for review by the editor - in - chief of this journal on request .
highlightswe report a rare case of cancer arising within fistulae in a crohn s disease patient.a deterioration of the fistulous disease may conceal a cancer development.examination under anaesthesia with biopsies or curettage of the fistulae is crucial.patients with fistulising crohn s disease should be kept under regular surveillance .