Review Question - QID 106765

This patient presents with multiple myeloma which will have large eosinophilic casts (Bence-Jones proteins) on renal biopsy as shown in Figure A.

Multiple myeloma (MM) is a monoclonal plasma cell malignancy that produces excess levels of immunoglobulins (IgG is more common than IgM and IgA). On peripheral blood smear, numerous plasma cells with "clock face" chromatin (Illustration A) will be observed along with rouleaux formation of red blood cells (RBC's stacked like poker chips) (Illustration B). Rouleaux formations occur when there is an increased plasma protein concentration, such as in MM which facilitates the aggregation of the unique flat discoid shape of the red blood cell. On kidney biopsy, large eosinophilic casts composed of Bence-Jones proteins will be observed. Bence-jones proteins are free immunoglobulin light chains that are not normally present in the urine.

Nau et al. review the diagnosis and management of multiple myeloma. They state that MM, the most common bone malignancy, is occurring with increasing frequency in older persons. Typical symptoms are bone pain, malaise, anemia, renal insufficiency, and hypercalcemia. Incidental discovery on comprehensive laboratory panels is common. The disease is diagnosed with serum or urine protein electrophoresis or immunofixation and bone marrow aspirate analysis.

George et al. review the treatment modalities of multiple myeloma. They state chemotherapy with melphalan-prednisone is the standard treatment for multiple myeloma. Other treatment modalities include polychemotherapy and bone marrow transplantation. Only 50 to 60 percent of patients respond to therapy.

Figures B-E are described in the incorrect answer choice explanations below. Illustration A demonstrates a plasma cell with the characteristic "clock face chromatin" in MM. Illustration B is the characteristic rouleaux formation of RBC's seen in MM.

Incorrect Answers:
Answer 2: Figure B demonstrates the histologic image associated with acute pyelonephritis. Note the neutrophilic infiltration into the renal interstitium.
Answer 3: Figure C demonstrates the histologic image associated with diabetic glomerulonephropathy. Note the mesangial expansion and eosinophilic nodular glomerulosclerosis (Kimmelstiel-Wilson lesion).
Answer 4: Figure D demonstrates the histologic image associated with rapidly progressive (crescentic) glomerulonephritis (RPGN). Note the crescentic moon shape of fibrin and plasma protein deposition.
Answer 5: Figure E demonstrates the histologic image associated with renal cell carcinoma. Note the clear, polygonal cells caused by the accumulation of lipids and carbohydrates.