4%plasma cells in bone marrow biopsy-how serious is it?

Can be normal. Up to 5% is normal as long as they are not "monoclonal" meaning derived from a cell. If monoclonal then a bone cancer called myeloma needs to be ruled out. If no bone disease, anemia, high calcium or kidney disease answer is MGUS, a pre-cancerous condition with low risk of progression (less than 1% per year).

Related Questions

Does the presence of bright cd8 t-cells on bone marrow biopsy indicate cancer?

Not really. Presence of cancer cells is only indication of cancer no other cells., to call it a cancer you have to see cancer cells nothing else . Cd-8 t cells are seen in viral infections also . These cells are some times seen surrounding the tumor or inside the tumor which is a good prognostic sign presence of immunity , body is fighting the cancer. Read more...