Perforated primary adenocarcinoma of the colon with choriocarcinoma differentiation treated with targeted colorectal cancer chemotherapy: a case report

Abstract

Background: Colorectal choriocarcinoma is a rare condition with a poor prognosis, and no standard chemotherapy regimen has been established. A combination of cetuximab, encorafenib, and binimetinib as adjuvant chemotherapy may be effective for colorectal choriocarcinoma. This treatment approach has not been previously reported for this rare malignancy.

Case description: We describe the case of a 59-year-old woman who underwent right hemicolectomy for a transverse colon perforation and was diagnosed with primary colorectal adenocarcinoma with choriocarcinoma differentiation. Adjuvant chemotherapy with folinic acid, fluorouracil, and oxaliplatin (FOLFOX) and bevacizumab was administered for colorectal adenocarcinoma, but disease progression was observed. The patient had a BRAF V600E mutation, tested negative for human chorionic gonadotropin (hCG), and was switched to a combination of encorafenib, cetuximab, and binimetinib. The treatment response was monitored through regular imaging studies and tumor marker measurements. The patient has been alive for 34 months with no metastases or recurrence, and with continued reduction in the size of the lymph nodes and peritoneal lesions.

Conclusions: Standard chemotherapy for the treatment of choriocarcinoma and colorectal adenocarcinoma has been applied to colorectal choriocarcinoma. In patients with a BRAF V600E mutation and decreased hCG levels, a combination of encorafenib, cetuximab, and binimetinib may be a useful chemotherapeutic option when treating patients with colorectal choriocarcinoma.

Keywords: Case report; chemotherapy; choriocarcinoma; colorectal adenocarcinoma; colorectal choriocarcinoma.

Figure 1

Contrast-enhanced computed tomography findings. (A) Axial image shows extraluminal free air (arrow) and ascites (arrowhead). (B) Axial image demonstrating edematous wall thickening of the transverse colon (arrowhead). (C) Coronal reconstruction reveals enlarged regional lymph nodes adjacent to the transverse colon (arrows).

Figure 2

Macroscopic findings. The transverse colon shows a type 4 tumor (100 mm × 50 mm) with perforation (arrowheads).

Figure 3

Immunohistochemical findings (magnification ×100) showing: (A) negative staining for cytokeratin 7; (B) positive staining for cytokeratin 20; (C) negative staining for CDX2; (D) negative staining for SATB2; (E) focal positive staining for hCG in 20–30% of tumor cells; (F) negative staining for SALL4. hCG, human chorionic gonadotropin.

Figure 4

Histological findings: (A) coexistence of colonic adenocarcinoma and choriocarcinoma (hematoxylin and eosin stain, magnification ×40). The white rectangle indicates the area shown in (B), and the red rectangle indicates the area shown in (C). (B) Abrupt transition from normal intestinal epithelium to tubular adenocarcinoma in the mucosa (hematoxylin and eosin stain, magnification ×100). The arrowhead indicates the site of the abrupt transition from normal epithelium to tubular adenocarcinoma. (C) Transition from tubular adenocarcinoma to choriocarcinoma in the deeper layers (hematoxylin and eosin stain, magnification ×100).