Abstract

Calcific ligamentitis of the lateral collateral ligament (LCL) is an extremely rare cause of lateral knee pain. Only fifteen cases were reported in the literature. It consists of a calcific deposit in the LCL and accompanying edema-like changes. It causes inflammatory pain, and conservative treatment has been successful in most cases. We reported a 44-year-old man with acute-onset lateral knee pain during the chemotherapy period for testicular seminoma. We reviewed all the reported cases and summarized them on a table. Plain radiography of our case demonstrated a well-circumscribed calcific deposit in the soft tissue adjacent to the lateral femoral condyle. Magnetic resonance imaging revealed its location in the proximal portion of the LCL and edema-like soft tissue changes. Pain was relieved with conservative treatment. Calcific ligamentitis of the LCL should be considered in the differential diagnosis of lateral knee pain. The combination of radiography and magnetic resonance imaging findings is useful in diagnosis, and radiography is sufficient during the follow-up period.