A 46-year-old woman presented with a right abdominal mass of more than 4-month duration. She had a normal diet, no abdominal pain or bloating, and could defecate, but the stools had no formed elements. Weight loss was not apparent. The patient had no relevant medical history, denied tobacco, alcohol, or drug use, and there was no family history of cancer. Symptomatic treatment did not result in improvement, and the abdominal mass increased significantly in the month before additional treatment was started. The patient had a doughy abdomen with tenderness and a palpable fist-sized mass in the right upper quadrant without rebound tenderness or muscle tension. Borborygmus was normal, the Douglas space was full, no nodules were involved, and no systemic lymph nodes were swollen. Proliferative masses near the splenic flexure of the colon prevented the completion of a colonoscopy. The pathological diagnosis was high-grade intraepithelial neoplasm.
A total abdominal enhanced computed tomography (CT) scan on January 12, 2016, showed irregular thickening of the wall of the hepatic flexure of the colon with narrowing of the lumen. Enhancement was uneven, the anterior abdominal wall was pushed forward, and the fat gap around it was blurred. The proximal ascending colon was slightly dilated, and a density shadow indicated that fluid surrounded the liver and spleen. Multiple nodules and mucoid densities were seen in the peritoneum and abdominal cavity; the septum was enhanced; mucoid lesions were not seen. There were clear enhancement and unclear demarcation of uterine and adjacent structures, and unclear imaging of uterine structures (Figure 1). The white blood cell count (10.16 x 109/L) and neutrophil percentage (80%) were high; hemoglobin was low (97 g/L). C-reactive protein (CRP, 134 mg/L), C-reactive protein (CRP, 41 ng/mL), carbohydrate antigen 19-9 (CA19-9, 96 U/mL), and carbohydrate antigen 125 (CA125, 240 U/mL) were high.
Abdominal enlargement continued following admission to the department of medical oncology, and chemotherapy was difficult to administer. Cytoreductive surgery with follow-up treatment was recommended by a multidisciplinary team of medical and surgical oncology, gynecology, imaging, and radiotherapy specialists considering ovarian metastasis of the transverse colon tumor and extensive abdominal and pelvic implantation of the myxoma. Surgery was performed on January 20, 2017. An 8 x 6 x 4 cm transverse colon mass that had infiltrated and adhered to the abdominal wall, about 2000 mL of mucous gelatinous tumor tissue, ascites, and both ovarian cysts, were completely removed (Figure 2). Hyperthermic intraperitoneal chemotherapy (HIPEC) was not performed during surgery because of a lack of disagreement among the patient's family members. Postoperative pathology confirmed a pT4bNxM1b mucinous adenocarcinoma of the transverse colon with metastasis to the serosa of both ovaries and the mesocolon. Immunohistochemical staining found that the primary tumor was CK7(-), CK20(+), CA125(-), CA19-9(+), CDX-2(+), cadherin17(+), P53(+++), PAX8(-), SATB2(+), beta-catenin(+), and 60% Ki-67(+) (Figure 3). Genetic testing revealed that the patient carried mutations in codon 12 in exon 2 of the KRAS gene and a V600E BRAF mutation, but no NRAS mutation. Unfortunately, the patient did not consent to treatment with a targeted drug because of a lack of insurance coverage.
A follow-up evaluation in September 2017 after surgery and 1 month after six cycles of capecitabine plus oxaliplatin (XELOX) chemotherapy found multiple lung metastases. The patient was switched to an irinotecan, raltitrexed, and Avastin regimen, but treatment was stopped in February 2019 because the patient could no longer tolerate chemotherapy. The patient died in July 2019, 29 months after diagnosis, because of malnutrition and inability to eat.