Differential Diagnosis for Metastatic Colon Cancer at the Belly Button

• Single most likely diagnosis
  • Sister Mary Joseph nodule: This is a metastatic tumor from a primary cancer, often from the colon, stomach, or ovary, that presents as a nodule at the umbilicus (belly button). The justification for this being the single most likely diagnosis is the specific location of the metastasis, which is a classic presentation for this condition.
• Other Likely diagnoses
  • Metastatic ovarian cancer: Ovarian cancer can also metastasize to the umbilicus, presenting similarly to a Sister Mary Joseph nodule. The likelihood of this diagnosis is due to the propensity of ovarian cancer to spread intraperitoneally and implant at distant sites, including the umbilicus.
  • Metastatic stomach cancer: Similar to colon and ovarian cancer, stomach cancer can metastasize to the umbilicus, although it is less common than Sister Mary Joseph nodules from colon cancer. The justification for including stomach cancer is its known potential for intraperitoneal spread.
• Do Not Miss diagnoses
  • Primary umbilical cancer: Although extremely rare, primary cancers can arise in the umbilicus, and missing such a diagnosis could be catastrophic. The importance of considering this diagnosis lies in its potential for aggressive behavior and poor prognosis if not promptly treated.
  • Infectious or inflammatory processes: Conditions like umbilical abscesses or granulomas could mimic a metastatic nodule clinically and would require urgent treatment to prevent serious complications. The justification for including these conditions is the potential for severe morbidity if not promptly diagnosed and treated.
• Rare diagnoses
  • Metastatic melanoma: While melanoma can metastasize to virtually any site, including the umbilicus, it is a less common cause of a nodule at this location compared to the other diagnoses listed. The rarity of this presentation justifies its placement in this category.
  • Other rare primary tumors: Tumors originating from the skin or soft tissues around the umbilicus, such as basal cell carcinoma or soft tissue sarcomas, could present as a nodule but are exceedingly rare. Their inclusion in the differential is necessary due to the broad range of potential pathology that could present at the umbilicus.