Neoplasms, or musculoskeletal lesions (tumors) are as rare as they are difficult to diagnose and treat. They may appear in any part of the body and there is no specific (pathogenic) presenting complaint or physical finding. They can involve almost any type of tissue including bone marrow, bone, cartilage, fibrous tissue, lymph tissues, blood vessels, and nervous tissue. In the knee, the diagnosis can be delayed because many disorders can cause similar symptoms.
There are many conditions that can mimic a neoplasm. Stress fractures, bone infections, certain metabolic diseases of the body, and simple bone conditions such as cysts can all present with the same symptoms as neoplasms. Neoplasms can be benign (non-cancerous) or malignant (cancerous). Fortunately, there are very few cases of malignant musculoskeletal tumors. Benign neoplasms are far more common.