What type of cancer is myeloma and where does it arise?

• A. Malignancy of melanocytes in skin.
• B. Cancer of plasma cells in bone marrow.
• C. Malignancy of lymphoid tissue in nodes.
• D. Myeloproliferative disorder.

Answer: (B)

Myeloma is a cancer of plasma cells, the specialized antibody-producing cells that come from B lymphocytes. These plasma cells normally reside in the bone marrow, where they develop and function. In myeloma, malignant plasma cells proliferate within the bone marrow, often producing a monoclonal antibody fragment and disrupting normal marrow function. This marrow-based origin and cell type distinguish it from cancers of pigment-producing skin cells (melanocytes), cancers arising in lymphoid tissue in lymph nodes (lymphomas), or broader myeloproliferative disorders. Therefore, myeloma is a plasma cell cancer that arises in the bone marrow.