Case report
A 52-year-old man with a 6-year history of UC (left-sided colitis) was
admitted to our hospital because of umbilical pain and low-grade fever.
Oral administration of 5-aminosalicylic acid had been discontinued one
year earlier due to clinical remission. A colonoscopy performed one year
earlier showed an endoscopic remission. At this time, a mild
inflammation was observed around the appendix orifice. He had no family
history of malignancies.
Physical examination on admission showed tenderness in the right lower
quadrant of the abdomen, but there was no peritoneal irritation sign.
Laboratory examination revealed an elevation of C-reactive protein
(2.01mg/dl), but tumor markers such as carcinoembryonic antigen and
carbohydrate antigen 19-9 were within normal range. A contrast
material-enhanced computed tomography scan showed a stenotic change of
the proximal ascending colon by a mass showing extramural growth
(Figure1A). The extramural part of the mass extended to the dilated
appendix with intraluminal tumor growth (Figure1B). A colonoscopy on
admission showed a circumferential stenosis of the proximal ascending
colon and the lumen was spread by air supply, suggesting extramural
compression. (Figure 2). The mucosa surface was reddish but intraluminal
growth of the tumor was not observed. Pathological examination of biopsy
specimens showed no malignancy.
A laparoscope-assisted right hemicolectomy was performed on the
9th day after admission. Macroscopically, the appendix
was dilated and strongly adhered to the proximal portion of the
ascending colon (Stage IIIB [T4b, N1a, M0] according to the TNM
classification). Pathological examination revealed a primary
adenocarcinoma mixed with an adenoma component of the appendix (Figure
3). The tumor invaded the serosal side of the proximal ascending colon.
Dysplasia was not identified in any pathologically examined specimens.
Genomic analysis of carcinoma cells revealed the KRAS G13D
mutation. His postoperative course was uneventful, and adjuvant
chemotherapy was started from 6 weeks after surgery.