Neurology & Pain Management Coding Alert

Question: Our doctor is doing a synovial cyst aspiration at L4-5. I’ve always used 349.2 (Disorders of meninges not elsewhere classified) for this procedure, but the physician says I should use 727.40 instead. Which code is correct? 

Wisconsin Subscriber

Answer: The key to the correct diagnosis code is the specific type of cyst – synovial rather than epidural. Synovium is the smooth lining of a joint, which produces synovial fluid that lubricates the cartilage and bones inside the joint capsule. In this case, your physician is referencing a paravertebral facet joint synovial cyst. The ICD-9 Alphabetic Index listing for Cyst, synovial directs coders to review ICD-9 code 727.40 (Synovial cyst, unspecified). Unlike most joints, the epidural space does not have a synovial lining. The facet joint cyst may bulge out of the facet joint into the epidural space, but the cyst itself is not of the dural membrane. Because the synovial cyst is associated with the actual joint instead of the dura, the most appropriate diagnosis code you should report for a synovial cyst of any spinal site is 727.40.