Successful Treatment of Disseminated Carcinomatosis of the Bone Marrow Secondary to Colorectal Cancer With Modified FOLFOX6 Plus Panitumumab: A Case Report

Disseminated carcinomatosis of the bone marrow (DCBM) is a rare, aggressive manifestation of colorectal cancer (CRC). It is often accompanied by pancytopenia and disseminated intravascular coagulation (DIC) and has a poor prognosis. Herein, we present the case of a 61-year-old male patient with sigmoid colon cancer and DCBM who presented with fever, fatigue, and DIC. Bone marrow biopsy confirmed poorly differentiated adenocarcinoma, consistent with the primary tumor. Genetic testing revealed the RAS and BRAF wild-type status. The patient was administered modified FOLFOX6 plus panitumumab as first-line chemotherapy. The patient's clinical symptoms improved rapidly, and transfusion dependency resolved after two cycles of chemotherapy. Subsequent comprehensive genomic profiling identified a subclonal <i>NRAS</i> G12D mutation; however, panitumumab treatment was continued because it was initially effective. Computed tomography performed two months later showed a marked reduction in liver metastases, and the patient sustained disease control since May 2025. To our knowledge, there are no previous reports of end-organ improvement and sustained response to chemotherapy containing an anti-EGFR antibody in a patient with CRC complicated by DCBM and DIC. This case highlights the potential benefits of early and appropriate therapy even in critically ill patients with rare metastatic patterns.