Knee pain and swelling: An atypical presentation of metastatic colon cancer to the patella.

Knee pain is a common reason for a patient to seek medical evaluation. Of the many causes of knee pain, malignancy is one of the least common. When malignancy is the etiology of the pain, it is usually due to a primary tumor of the osseous structures or soft tissues of the knee joint. Metastatic disease involving the knee joint is uncommon, with few cases reported in the literature. Of these reported cases, metastatic colon cancer is exceedingly rare. However, in a patient with new onset knee pain and the proper clinical history, metastatic disease should be considered as a potential explanation of symptoms. We report a case of knee pain and swelling due to metastatic colon cancer to the patella.