ventriculoperitoneal and cystoperitoneal ( cp ) shunts are commonly used for the treatment of hydrocephalus and symptomatic intracranial cysts . abdominal complications , including intestinal volvulus , pseudocyst formation and migration into the gastrointestinal tract have been reported , accounting for 25% of shunt - related complications . bowel perforation by the shunt catheter is uncommon and accounts for 0.010.07% of all abdominal complications [ 13 ] . breast - related complications represent a class of thoracic shunt complication and are characterized by breast cerebrospinal fluid ( csf ) pseudocyst formation , csf galactorrhoea and shunt obstruction . we report a rare case of acute mastitis caused by enteric organisms passing through a cp shunt catheter , which had penetrated the transverse colon , and was related to a previous failed attempt to remove the shunt resulting in a divided catheter . the patient is a 56-year - old woman who underwent a surgical treatment of a lateral ventricle meningioma at the age of 29 . the postoperative course was uneventful and she was well without shunt - related problems for 26 years . she developed a brain abscess related to the shunt catheter at the age of 55 . a surgical removal of the catheter was attempted , but was not technically possible , and only the segment from the clavicle to the breast was removed with ligation of the two remaining ends . a year later , she was taken to a local hospital with continuous right - breast pain . the diagnosis of acute mastitis was made and she was referred to our institution for further examination . on presentation , her temperature was 36.7c , and laboratory tests revealed a decreased platelet count of 103 000/l , elevated ast of 97 u / l , alt of 72 u / l and c - reactive protein level of 1.4 mg / dl . cultures taken from the abscess showed enteric organisms including enterococcus avium , klebsiella oxytoca and bacillus . abdominal ct showed that the shunt catheter was in the splenic flexure of the transverse colon with no other abnormalities ( fig .  2 ) . colonoscopy was performed to survey the colon and the shunt catheter was found inside the lumen at the splenic flexure ( fig . acute mastitis caused by enteric organisms which had migrated through the shunt catheter after penetration into the transverse colon was the presumptive diagnosis , and the catheter removed under general anesthesia . the breast to the abdomen segment of the catheter was exteriorized through the right - anterior chest wall without laparotomy . the shunt catheter ( white arrow ) extended through the right - rectus sheath ( a ) , crossed the midline to the left side of the abdomen ( a , b ) and was inside the splenic flexure of the colon ( b , c ) . figure  3:colonoscopy showed the distal catheter within the transverse colon , 40 cm proximal to the anal verge ( a ) . an inflammatory polyp was present at the penetration site in the colon wall ( b ) . the shunt catheter ( white arrow ) extended through the right - rectus sheath ( a ) , crossed the midline to the left side of the abdomen ( a , b ) and was inside the splenic flexure of the colon ( b , c ) . colonoscopy showed the distal catheter within the transverse colon , 40 cm proximal to the anal verge ( a ) . an inflammatory polyp was present at the penetration site in the colon wall ( b ) . the penetration of shunt catheters into the intestine at the distal end is rare with a reported incidence between 0.01 and 0.07% . the mortality rate may be high , up to 15% , due to intracranial or intra - abdominal infections . several factors have been found to be responsible for this rare complication , including chronic irritation of the gastrointestinal tract , prior abdominal surgery or silicone allergy [ 2 , 3 ] . csf leakage and retrograde flow from the peritoneal cavity to the breast may cause breast - related complications . this is the first report of case with acute mastitis caused by enteric organisms migrating through a cp shunt catheter that had penetrated the transverse colon . the diagnosis of bowel perforation by a shunt may not be easy to make , unless the shunt protrudes from the anus [ 5 , 6 ] . prolonged diarrhea of unknown etiology , as well as abdominal symptoms , serves as warning signs of possible bowel perforation . ct can play a crucial role in the diagnosis of bowel perforation . in the present case , these findings suggested that the infection was due to the retrograde flow from the colon . the development of mastitis was facilitated by previous division of the catheter , leaving a ligated end . presumably , the ligature became dislodged , leaving a direct connection from the breast tissue to the distal end of the catheter . previous study reports that the shunt catheter can be directly removed percutaneously in 69% ( 31/45 ) , whereas 17% ( 8/45 ) of patients require a laparotomy and repair of the bowel . if there is evidence of significant abdominal infection , such as an abscess or life - threatening peritonitis , the fistulous opening may not close spontaneously , warranting laparotomy . in the present case , previous insufficient surgical treatment such as a partial removal of the catheter contributed to this shunt - related complication . however , it is common surgical practice to permit the distal end of a shunt catheter to remain in situ in order to simplify the surgical procedure . although this practice is most commonly uncomplicated , it is not unreasonable to suspect that the tube may irritate the serosal surface of the colon leading to chronic inflammation . it is speculated that local inflammation owing to repeated irritation of the bowel wall by the catheter tip might have contributed to the subsequent perforation . in conclusion , a patient who presents with acute mastitis and has previously undergone shunt placement should undergo assessment of the abdominal segment of the catheter .
we report a rare case of acute mastitis caused by enteric organisms passing through a cystoperitoneal shunt catheter , which had penetrated into the colon . 
 the patient is a 56-year - old woman who underwent shunt placement for cyst formation after surgery for meningioma at the age of 29 . after 26 years , she suffered from a brain abscess and an attempt was made to surgically remove the indwelling catheter . 
 only part of the catheter could be removed , leaving a divided and ligated catheter in situ . 
 a year later , she described right - breast pain . 
 ct showed that the catheter had migrated into the colon , followed by colonoscopy confirming that the catheter had indeed penetrated the colon . 
 the breast to the abdomen segment of the catheter was exteriorized through the right - anterior chest wall without laparotomy . 
 a patient who presents with acute mastitis and has previously undergone shunt surgery should have a careful assessment of the entire catheter .