A 68-year-old man is evaluated for exertional fatigue. He used to play tennis actively but now is having a hard time finishing a set. His only other medical problem is hypertension. He does not use tobacco, alcohol, or illicit drugs. Temperature is 37 C (98.6 F), blood pressure is 126/86 mm Hg, and pulse is 82/min. Mild mucosal pallor is present. There is no lymphadenopathy. Cardiopulmonary examination is normal. There is no splenomegaly or lower extremity edema. Laboratory results are as follows: Peripheral blood smear is shown in the exhibit. Which of the following is most likely to be found on the patient's bone marrow biopsy?

Question

A 68-year-old man is evaluated for exertional fatigue.  He used to play tennis actively but now is having a hard time finishing a set.  His only other medical problem is hypertension.  He does not use tobacco, alcohol, or illicit drugs.  Temperature is 37 C (98.6 F), blood pressure is 126/86 mm Hg, and pulse is 82/min.  Mild mucosal pallor is present.  There is no lymphadenopathy.  Cardiopulmonary examination is normal.  There is no splenomegaly or lower extremity edema.  Laboratory results are as follows:  Peripheral blood smear is shown in the exhibit.  Which of the following is most likely to be found on the patient's bone marrow biopsy?

Quizplus · Accepted Answer

Multiple myeloma (MM) is a plasma cell neoplasm that often presents with constitutional symptoms (weight loss, fatigue) or bone pain. MM should be suspected in elderly patients with laboratory findings of hypercalcemia, normocytic anemia, renal insufficiency, and a protein gap (difference between total protein and albumin >4 g/dL). A protein gap indicates elevated nonalbumin protein in the serum; it may be seen with polyclonal gammopathies (infection, connective tissue disease) or excessive monoclonal protein (MM, Waldenström macroglobulinemia). Serum protein electrophoresis (SPEP) can determine if a protein gap is caused by a monoclonal or polyclonal source. In MM, SPEP typically shows a monoclonal spike (M-spike). Diagnosis is then confirmed by bone marrow biopsy (>10% clonal plasma cells). This patient's peripheral blood smear shows rouleaux formation (stacking of red blood cells like coins), a finding seen with elevated serum protein. (Choice B) Patients with myelofibrotic disorders may have hypocellular, fibrotic bone marrow. Manifestations of myelofibrosis include fatigue, anemia, and hepatosplenomegaly. Elevations in protein gap and hypercalcemia are not typical features of myelofibrosis, making MM more likely. (Choice C) In aplastic anemia, bone marrow biopsy often shows a hypoplastic, fat-filled marrow. Despite its name, aplastic anemia causes pancytopenia (not simply anemia). This patient has a normal leukocyte and platelet count. (Choice D) Megaloblastic erythroid hyperplasia is seen in megaloblastic anemia, typically caused by vitamin B₁₂ or folate deficiency. Megaloblastic anemia would cause an elevated mean corpuscular volume (>100 µm³) and would not explain the protein gap or hypercalcemia. (Choice E) Ring sideroblasts are seen in the sideroblastic anemias, which typically present with microcytic anemia with hemoglobin <7 g/dL. Sideroblastic anemia would not account for the protein gap or hypercalcemia found in this patient. Educational objective: Multiple myeloma (MM) is a plasma cell neoplasm that infiltrates the bone marrow and may cause a monoclonal protein elevation (M-spike). MM is associated with hypercalcemia, anemia, renal insufficiency, and an elevated protein gap (>4 g/dL).

A 68-Year-Old Man Is Evaluated for Exertional Fatigue