Review Question - QID 105637

The patient in the question stem has multiple myeloma. Multiple myeloma is characterized by proliferation of plasma cells, which are abundant in rough endoplasmic reticulum.

Multiple myeloma is a neoplastic proliferation of plasma cells (differentiated B lymphocytes) found in the bone marrow. These cells are capable of producing and secreting large amounts of protein, hence, the abundance of rough endoplasmic reticulum. In normal bone marrow, there is a polyclonal distribution of cells and immunoglobulins; however, in multiple myeloma the monoclonal proliferation of plasma cells often produces immunoglobulin of only one isotype, leading to an M spike on serum protein electrophoresis.

Nau and Lewis describe multiple myeloma as the most common bone malignancy. Incidental discovery is very common on laboratory surveillance. As with this patient, the authors report that the disease is diagnosed with serum or urine protein electrophoresis or immunofixation and bone marrow aspirate analysis. They report that skeletal radiographs are important in staging multiple myeloma with the revelation of lytic bone lesions. Treatment of symptomatic disease includes a variety of chemotherapeutic agents followed by autologous stem cell transplantation, when possible.

Greipp reports on the sometimes indolent and asymptomatic nature of multiple myeloma sharing that 5-15% of patients who satisfy criteria for the diagnosis of multiple myeloma have no or minimal symptoms and do not require chemotherapy. In these patients, close monitoring and the use a nonchemotherapeutic agents, such as dexamethasone to reduce tumor burden, bisphosphonates to prevent osteoporosis, and erythropoietin to correct anemia can sometimes be sufficient. Importantly, they note that 25% of patients receiving alkylating agents develop myelodysplastic syndrome or acute leukemia, which must be monitored.

Figure A demonstrates multiple lytic bones lesions of the lumbar spine. Illustration A demonstrates the normal distribution of serum proteins vs those found in multiple myeloma patients on serum protein electrophoresis. Illustration B shows bone marrow biopsy of multiple myeloma patient demonstrating high level of endoplastic reticulum.

Incorrect Answers:
Answers 1-2, 4-5: Differentiated plasma cells are not specifically known to be more abundant in mitochondria, Golgi bodies, smooth endoplastic reticulum, or lysosomes than other cells.