Since only one craniectomy was performed, you can only report it once. Chose the code that best describes the procedure and the location. Using Modifier 22 does not mean there were multiple tumors removed, only that work required was substantially greater than typically required. The documentation should reflect the work and time spent on the extra tumors to indicate the detail of the complexity, but you cannot bill additional procedures.
22-Increased procedural services: when the work required to provide a service is substantially greater than typically required, it may be identified by adding modifier 22 to the usual procedure code