ABSTRACT
A 69-year-old female was presented with a history of sigmoid colon cancer, uterine cancer, and intrahepatic carcinomas. After computed tomography revealed a disseminated nodule located in the peritoneum, colonoscopy demonstrated a rather flat-to-slightly elevated lesion with a depressed area located in the ascending colon. The flat component showed color similar to its surrounding area, and the depressed area showed redness and an expanded appearance. We obtained a biopsy specimen from the depressed area, and microscopic examination revealed well-differentiated adenocarcinoma, which was immunohistochemically positive for BRAF V600E-mutated and PMS2 proteins, and showed loss of MSH2 and MSH6 protein expressions. These findings suggested the lesion to have transformed from a sessile serrated lesion (SSL) to mismatch repair (MMR) deficient colon cancer. The patient underwent surgical removal of the nodule, which interpreted as metastasis of intrahepatic cholangiocarcinoma histopathologically. After postoperative chemotherapy, the follow-up colonoscopy revealed only the flat portion of the lesion without depressed area. Consequently, we performed an endoscopic resection, and microscopic examination confirmed the existence of BRAF V600E-mutated protein-positive and MMR protein-retained SSL without residual carcinoma. This is the first report of BRAF-mutant and MMR-deficient colon cancer, in association with SSL, showing regression.
ABSTRACT
Although most immune-related adverse events (irAEs) secondary to immune checkpoint inhibitors can be managed with immunosuppressive therapies; they can induce reactivation of infectious diseases, including cytomegalovirus (CMV). Here, we show a case of CMV enterocolitis during steroid therapy for an irAE. A 77-year-old man with unresectable malignant melanoma was treated with ipilimumab. He suffered from immune-related colitis (irColitis) and was treated with methylprednisolone. Although corticosteroids initially improved his symptoms, CMV reactivation occurred and colitis was exacerbated. Antiviral therapy improved his symptoms without augmenting the immunosuppressive therapy. CMV colitis should be considered when a patient with irColitis shows resistance to immunosuppressive therapy.
