[Patellar metastasis of colon carcinoma. A rarity in differential diagnosis of acute knee pain. Case report].

Although bone tumors are often located in the knee area, primary tumors of the patella are rare, and patellar metastases extremely rare. Only a few cases were reported in the literature originating from different primary tumors, mostly lung and breast [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 19, 20, 22]. There is only one other case description of a colon carcinoma [21]. We present a rare case of primary sigma carcinoma and patellar metastasis. Because of the increasing rate of colon carcinomas, neoplastic disease must be considered in the differential diagnosis in any patient with otherwise unexplained knee pain.