Hypercellular is a term pathologists use to describe an increased number of cells compared to normal in an area of the body. It is a descriptive term and not a diagnosis. Hypercellular can be used to describe both benign (non-cancerous) groups of cells and malignant (cancerous) tumours. Pathologists commonly use the term hypercellular when describing the changes seen in a bone marrow biopsy where there is an increased number of cells compared to what is normally present in the bone marrow. The opposite of hypercellular is hypocellular.