Neuroendocrine tumors (NETs) are a rare and heterogeneous group of malignancies originating from the diffuse neuroendocrine system, with gastrointestinal tract being the most commonly affected site, while colorectal involvement is relatively rare.

This report presents a 67-year-old Iranian man with a history of liver cirrhosis presenting with flushing, nausea, vomiting, coughing, shortness of breath, non-bloody persistent diarrhea, and severe recent weight loss. Sepsis work-ups were all negative. Imaging studies revealed multiple hypodense and hypovascular hepatic masses. Biopsy was taken from these masses, and both histopathological analysis and immunohistochemical (IHC) staining revealed well-differentiated colorectal neuroendocrine carcinoma (G2), with positivity for Chromogranin, Synaptophysin, CK19, CDX2, and Ki-67. Palliative care and octreotide were administered; however, the patient sadly passed away after two months of follow-up.

In conclusion, colorectal NETs may metastasize to the liver, which can be definitively diagnosed by IHC staining of liver masses.