November 2000: 13 year old girl with back pain and leg weakness - Diagnosis - Pigmented villonodular synovitis.

The November COM: A 13 year-old girl presented with back pain and recurrent falls of one year, with more recent loss of ambulation and bladder control . Examination showed spasticity and a sensory level bilaterally at T8. CT a nd MRI scans showed an epidural soft tissue mass with spinal cord compressi on and destruction of the pedicle, transverse process and other portions of a mid-thoracic vertebral body. Histologic examination of the gross total r esection showed a pigmented villonodular synovitis (PVNS). PVNS is most com mon in the knee and only 26 cases have been reported in the spine. Although vertebral bodies are rarely involved, it is important to include PVNS in t he differential diagnosis of spinal lesions because of its tendency to recu r locally if not totally resected.