A Rare Case of an Occult Primary Tumor With a Profile of Colon Cancer and Synchronous Metastasis in the Lung, Liver, Bone, and Cerebellum: A Case Report and Literature Review.

Occult primary tumors, or cancers of unknown primary site (CUP), are an oncological pathology characterized by the presence of metastases but without being able to determine the presence of the primary tumor. These types of tumors are very rare, and they pose challenges for diagnosis and treatment. Colorectal cancer is the most common type of malignant tumor worldwide and the second most common cause of death. The most common sites of metastasis in colorectal cancer are hepatic and pulmonary. Relatively rare, patients develop brain and bone metastasis. We reported a rare case of an occult primary tumor with a profile of colon cancer and synchronous metastasis in the lung, liver, bone, and cerebellum developed in a woman who was only 51 years old.