a 44-year - old male was visited for back pain and mass around left buttock .
he had a medical history that included a diagnosis of pulmonary tuberculosis , from which he had recovered completely 20 years previous .
he was under medication from a local clinic and pharmacy for 1 month prior to visiting the hospital due to cold symptoms and lower back pain .
vital signs on visit were blood pressure at 130/80 mmhg , heart rate at 72 beats / minute , respiratory rate at 18/minute and body temperature was 38.3. the mass was painful and palpated on the left buttock area , and is seen as a reddish skin color around the anterior superior iliac spine ( fig .
laboratory investigations on admission were the following : white blood cell count was 16,660/mm , hemoglobin was 10.5 g / dl , platelet count was 631,000/mm , c - reactive protein was 21.9 mg / dl , and erythrocyte sedimentation rate was 120 mm / hour .
abdominal computed tomography ( ct ) and magnetic resonance imaging ( mri ) showed a large psoas abscess in retroperitoneal space and abscess on left lower quadrant anterior abdominal wall ( fig .
2 ) . based on a diagnosis of psoas abscess , the patient was given ciprofloxacin and metronidazole as an empirical injection , then an incision and drainage was performed .
ciprofloxacin and metronidazole were injected for an additional 7 days after this procedure , however streptococcus agalactiae and streptococcus aginosus were cultured .
a skin defect , 4  3 cm in size , developed around left anterior superior iliac spine .
ten days post discharge , the patient experienced fecal discharge from the local flap site ( fig .
the patient underwent an operation for enterocutaneous fistula , which was performed by the department of general surgery . during the surgical procedure ,
a tumor mass was found in the descending colon and was adherent to the retroperitoneum .
the tumor had ruptured spontaneously and formed enterocutaneous fistula track , but there were no peritoneal seeding .
the histopathologic results of the fistula track and capsule of abscess were granulation tissue with acute suppurative inflammation without tumor cell .
reported cases of psoas abscesses have been attributed to tuberculous diseases of the spine , infective spondylitis , crohn 's disease , and diverticulitis.3 ) the incidence of perforated colon cancer ranges from 3% to 10%.4 ) development of intra - abdominal abscess from spontaneous rupture of colon cancer is very rare , having an incidence of 0.3 - 0.4%.1,2 ) the psoas muscle is a retroperitoneal structure lying outside the endoabdominal fascia , such that it is protected from intra - abdominal muscle.5 ) similar to this case , a psoas abscess from colon cancer usually has been preceded by perforation of cancer and commonly with fistula formation .
abdominal ct is useful in diagnosis and mri helps in judgment of abscess location , determination of lesion boundaries , and the spread to surrounding soft tissue . in this case , the patient was relieved of symptoms from the psoas abscess by routine incision , drainage and antibiotic therapy in this case .
however , the wound culture from the operation was positive for s. agalactiae and s. aginosus which are unusual findings from this location .
this led the authors to doubts about the original diagnosis of an uncomplicated psoas abscess and prompted the taking of abdominal ct and mri .
we discovered that the patient 's intra - abdomen was connected with retroperitoneum and fecal discharge , which were observed on the local flap . during the operation under enterocutaneous fistular impression
, we found a ruptured tumor mass in the descending colon , which had adhered and connected to the retroperitoneum .
the case report concerned a thigh abscess with perforated colon cancer ; the route by which the abscess spread from abdominal sources were by 2 means in this case : one was the direct soft tissue extension of infection from the extraperitoneal portion of colorectum ; the second was the extension of infection into the other site via naturally occurring defects in the abdominal wall.6 ) as previously described , perforated colon cancer is rare .
fistular formation is uncommon and occurs only in approximately 15% of all perforated colon cancers.7 ) in this case , abscess and fistula of perforated colon cancer were coexistent .
it must be recognized that ruptured colon cancer can be a rare cause of psoas abscess .
if the result of wound culture is an uncommon strain or normal flora of bowel and the patients have continuous wound problem , surgeons should consider spontaneous rupture of colon cancer as part of the differential diagnosis in these cases .
 spontaneous rupture of colon cancer , combined with psoas abscess formation , is rare . 
 a 44-year - old male visited for back pain and left buttock mass . 
 abdominal computed tomography and magnetic resonance image revealed a large abscess in the left psoas muscle and in the left lower quadrant area . 
 ten days after incision and drainage , a skin defect around the left anterior superior iliac spine remained . 
 a local flap was performed using a superficial skin graft . 
 ten days after the stitches had been removed , fecal discharge was observed around the anterior superior iliac spine at the flap site . 
 an operation was performed by a general surgeon who had diagnosed this as a case of enterocutaneous fistula . 
 operative findings included a ruptured tumor mass in the descending colon , which was connected to a retroperitoneal abscess . 
 pathologic report findings determined adenocarcinoma of the resected colon . 
 herein , we report a case of psoas abscess resulting from perforating colon cancer . 
CASE REPORT
DISCUSSION