Cutaneous metastasis of cecum cancer with MSI-high and BRAFV
Cutaneous metastases of colorectal cancer (CRC) are rare, occurring in 0.7% to 5% of cancer patients. Furthermore, the molecular subtypes of cutaneous metastasis of CRC are unclear. Here, we present a rare case of cutaneous metastasis of high-frequency microsatellite instability (MSI-high)/BRAFV600E-mutant cecum cancer.

A 77-year-old woman presented at the outpatient clinic with a subcutaneous mass on her left-back. An excisional biopsy was performed and metastatic cutaneous adenocarcinoma was diagnosed. A computed tomography scan of the thorax and abdomen showed thickening of the cecum wall, the presence of pericolic lymph nodes, multiple masses in the liver, and a single nodule in the right lung. Right colectomy with D2 lymphadenectomy and functional end-to-end anastomosis was performed because of the almost complete intestinal obstruction. The expression of KRAS wild type, BRAFV600E mutation, and MSI-high was detected in the cecum cancer using the molecular pathological examination. She received chemotherapy with XELOX?+?BEV regimen (capecitabine?+?oxaliplatin?+?bevacizumab). After four administrations, a computed tomography scan showed a reduction of distant metastases, which suggested partial response.