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colonic diverticulosis refers to the formation of small outpouchings from the colonic lumen due to mucosal herniation through the colonic wall at sites of vascular perforation .
although most patients affected will remain entirely asymptomatic , some patients have clinical syndromes , mainly diverticulitis and diverticular haemorrhage .
it is also well known that diverticular disease of the colon can lead to fistula formation .
the commonest fistula of the colon caused by diverticular disease is a colovesical fistula , and colocutaneous fistula is relatively rare [ 2 , 3 , 4 ] .
we herein report a rare case of delayed recrudescent sigmoidocutaneous fistula due to diverticulitis . in this case , conservative therapy was not effective and low anterior resection with fistulectomy was performed .
this case also implies the possibility of recurrence of the fistula even if the conservative treatment was effective .
on 12 february 2007 , a 56-year - old japanese man was admitted to our hospital with a complaint of lower abdominal pain .
the patient had been suffering from colocutaneous fistula after a drainage operation against perforation of the sigmoid colon diverticulum . a drainage procedure and a closure of the perforated colon with covering stoma
after 5 years of symptom - free period , he was admitted to our hospital because of lower abdominal pain around the scar of the surgical wound left after the drainage .
, a physical examination revealed that the patient had a height of 169 cm , a weight of 62.5 kg , a heart rate of 92 beats per minute with regularity , and blood pressure of 125/91 mm hg .
his white blood cell count was 11,670/mm , and c - reactive protein was 10.08 mg / dl .
because of the inflammatory reaction , the incision and drainage procedures were performed and the patient was treated with antibiotics .
abdominal radiography revealed no remarkable findings . computed tomography of the abdomen showed a high - density area around the site of drain insertion and the rectus abdominis muscle in contact with the diverticulum of the sigmoid colon ( fig .
sigmoidocutaneous fistula due to diverticulitis was clinically suspected , and we diagnosed a recrudescent sigmoidocutaneous fistula by gastrografin enema ( fig .
2 ) . this enema revealed diverticulosis of the sigmoid colon and fistula formation of the sigmoid colon near the rectum .
the diagnosis was confirmed by fecal exudates observed from cutaneous fistula in the course of conservative treatment .
the patient was managed with total parenteral nutrition and antibiotics . the abdominal pain improved after treatment began , but the fistula formation did not improve , as confirmed by gastrografin enema .
it was found that apparent adhesion and fibrosis were located mainly around the rectum to the sigmoid colon , where the perforated diverticulum of the sigmoid colon was recognized .
the fistula wall consisted partly of serosa of the ileum and bladder wall , and the fistula was continuous with cutaneous tissue .
granulomatous inflammation and fibrosis were also observed at the fistula wall , composed of ileum or bladder . from these findings ,
sigmoidocutaneous fistula due to diverticulitis was diagnosed and a low anterior resection with fistulectomy was performed ( fig .
fistulas with diverticular diseases may involve any pelvic structure including urinary bladder , vagina , uterus , fallopian tube , ureter , other parts of the colon or ileum , and cutaneous tissue .
the colovesical fistula is the most common internal fistula , and a colocutaneous fistula is relatively uncommon [ 2 , 3 , 4 ] .
a previous study reported that the type of fistulas included colovesical ( 48% ) , colovaginal ( 44% ) , coloenteric ( 2% ) , colotubal ( 2% ) , and colocutaneous ( 4% ) fistulas .
colocutaneous fistula occurs almost exclusively as a complication of operation , and spontaneous colocutaneous fistulas are rare [ 5 , 6 ] .
the cause for the fistula fomation of this case was also considered attributable to the previous operation .
interestingly , this case was a recurrent case of fistula . clinically , with conservative therapy it may be difficult to cure the fistula completely .
thus , recurrent cases of fistula of the colon caused by diverticular disease are very uncommon .
furthermore , this case implies that radical surgery is needed to remove a fistula due to diverticular disease , because this case shows the possibility of a recurrence of the fistula even though the conservative treatment was effective . a complicating disease with diverticulitis , such as an abscess or phlegmon , can be managed conservatively , and subsequent surgery is selective depending on the recovery from the initial episode . however , a fistula often requires surgery .
certainly , some reports have shown that a fistula can be managed with a course of nonoperative treatment [ 3 , 8 ] .
however , most fistulas due to diverticulitis are dealt with by a surgical procedure and can be safely managed by resection and primary anastomosis in many cases [ 2 , 3 , 4 , 9 , 10 ] .
conservative therapy may help improve acute inflammatory reaction and may make operations easier , but closure of the fistula by conservative treatment may not be possible .
clinically , a patient with a fistula should first be managed with total parenteral nutrition and antibiotics to reduce inflammation , and only then should an operation be performed . in this case , after conservative therapy , a low anterior resection with fistulectomy was performed and provided good results . in conclusion , we here reported a rare case of delayed recrudescent sigmoidocutaneous fistula due to diverticulitis . in cases of colocutaneous fistulas due to diverticulitis ,
radical surgery should be considered necessary because of possibility of a recurrence of the fistula even though the conservative treatment was effective .
colocutaneous fistula caused by diverticulitis is relatively rare , and a delayed recrudescent case of colocutaneous fistula is very uncommon . 
 we herein report a rare case of a japanese 56-year - old male with delayed recrudescent sigmoidocutaneous fistula due to diverticulitis . 
 a colocutaneous fistula was formed after a drainage operation against a perforation of the sigmoid colon diverticulum . 
 after 5 years from treatment , he was admitted to our hospital because of lower abdominal pain . 
 we diagnosed the recrudescent sigmoidocutaneous fistula by abdominal computed tomography and gastrografin enema , and managed the patient with total parenteral nutrition and antibiotics . 
 as the fistula formation did not improve , a low anterior resection with fistulectomy was performed . 
 the postoperative course was uneventful and the patient was discharged . 
 it has been reported that , in fistulas of the skin caused by diverticular disease , complete closure of the fistula by conservative therapy may not be possible . 
 this case also implies the possibility of a recurrence of the fistula even if the conservative treatment was effective . in cases of colocutaneous fistulas due to diverticulitis , radical surgery 
 is considered necessary because of possibility of recurrence of the fistula .