Take the bureau outside on a nice warm, sunny day. With a sponge dampened with a mix of 5 parts water to one part household bleach, like Clorox, wash it all, inside and outside. Don't forget to do the drawers. Just use a damp sponge and between the bleach and the sun, you should kill any mold or mildew.
When the piece has dried completely, put a "spit coat" of shellac on the unfinished, interior surfaces. Do not get this on the finished parts of your bureau as it may ruin the finish.
A spit coat is one part 3# cut white shellac (Zinnser's is a good and well known brand) to 5 parts denatured alcohol. Apply this with one of the cheap, natural bristle, wooden handled brushes to any unfinished wood. Do parts like the inside of the panels that form the desk and the unfinished parts of drawers. This will seal almost any odor in. The shellac, brushes and alcohol will be available in the paint department of any good home center and in many big box retailers.