Differential Diagnosis for Right Colon Mass
Single most likely diagnosis
- Colorectal adenocarcinoma: This is the most common type of cancer affecting the colon, and a mass in the right colon with characteristics described is highly suggestive of this diagnosis. The extension over a length of about 12 cm and potential invasion into adjacent structures like the gallbladder and duodenum are consistent with an aggressive neoplasm such as colorectal adenocarcinoma.
Other Likely diagnoses
- Lymphoma: Although less common than adenocarcinoma, lymphoma can present as a mass in the colon and may extend over a significant length. It can also invade adjacent structures.
- Gastrointestinal stromal tumor (GIST): While more commonly found in the stomach, GISTs can occur in the colon and may present as a large mass. However, their tendency to invade adjacent organs like the gallbladder and duodenum is less typical compared to adenocarcinoma.
- Metastatic disease: The right colon can be a site for metastasis from other primary cancers, such as melanoma, breast cancer, or other gastrointestinal cancers. However, a primary metastatic lesion in the colon would be less common than a primary colorectal cancer.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Appendiceal cancer: Although rare, if the mass is located near the appendix, appendiceal cancer could be a consideration. It's crucial to diagnose and treat promptly due to its potential for aggressive behavior and poor prognosis if missed.
- Invasive infectious process: In rare cases, an infectious process (e.g., invasive amoebiasis or tuberculosis) could mimic a neoplasm. Missing such a diagnosis could lead to inappropriate treatment and significant morbidity or mortality.
Rare diagnoses
- Carcinoid tumor: These neuroendocrine tumors can occur in the colon but are less common than adenocarcinoma. They might not typically present as a large, invasive mass.
- Leiomyosarcoma: A rare type of smooth muscle tumor that can occur in the colon, presenting as a mass. However, it is much less common than adenocarcinoma or other diagnoses listed above.
- Intussilo: Although more common in children, intussilo (telescoping of a segment of intestine into another) can rarely occur in adults and might mimic a mass on imaging. It is usually associated with a lead point, which could be a neoplasm.