An unusual case of tophaceous gout involving the anterior cruciate ligament.

Abstract We describe a very unusual case of a 49-year-old man with tophaceous gout involving and infiltrating the base of the anterior cruciate ligament of the left knee. To our knowledge, such a case has never been reported in the literature, although gout is well known and widely studied. Magnetic resonance imaging findings and differential diagnosis were analyzed before arthroscopy. Tophaceous gout was suspected at arthroscopy and confirmed on pathologic examination. Treatment consisted of partial removal of the tumor by arthroscopy, conserving the anterior cruciate ligament.

Mucoid degeneration of the anterior cruciate ligament with erosion of the lateral femoral condyle.

We report a case of a mucoid degeneration of the anterior cruciate ligament (ACL) that produced osseous erosion of the medial aspect of the lateral femoral condyle. The MRI findings and differential diagnosis are discussed.