A 25-year-old woman comes to the office due to significant fatigue. Several weeks ago, the patient had a weeklong episode of intermittent fever and severe body aches. Over the last 2 weeks, she has been too tired to complete her normal jogging routine in the mornings and has had to take naps after returning home from work. The patient has no chronic medical conditions and takes no medications. Temperature is 37.2 C (99 F), pulse is 110/min, and respirations are 20/min. Examination shows pale lips and conjunctivae. The abdomen is soft and there is no hepatosplenomegaly. Examination of the extremities is unremarkable, and no lymphadenopathy is present. Laboratory results are as follows: Peripheral blood smear reveals normocytic, normochromic red blood cells, and other cell types appear morphologically normal. This patient's bone marrow biopsy would most likely show which of the following patterns?

Question

A 25-year-old woman comes to the office due to significant fatigue.  Several weeks ago, the patient had a weeklong episode of intermittent fever and severe body aches.  Over the last 2 weeks, she has been too tired to complete her normal jogging routine in the mornings and has had to take naps after returning home from work.  The patient has no chronic medical conditions and takes no medications.  Temperature is 37.2 C (99 F), pulse is 110/min, and respirations are 20/min.  Examination shows pale lips and conjunctivae.  The abdomen is soft and there is no hepatosplenomegaly.  Examination of the extremities is unremarkable, and no lymphadenopathy is present.  Laboratory results are as follows:  Peripheral blood smear reveals normocytic, normochromic red blood cells, and other cell types appear morphologically normal.  This patient's bone marrow biopsy would most likely show which of the following patterns?

Quizplus · Accepted Answer

11ec160b_396e_8b8a_9249_03c887d6cf53_MD0001_00 This patient with pancytopenia has inappropriately low reticulocyte count, morphologically normal cell lines on peripheral smear, and no splenomegaly on physical examination, raising strong suspicion for aplastic anemia. Aplastic anemia is a form of bone marrow failure caused by direct toxic injury or cytotoxic T-cell destruction of multipotent hematopoietic stem cells in the bone marrow. Because these stem cells generate progenitor cells that produce all blood cells, damage results in a dramatic reduction of immature and mature blood cells in the bone marrow and peripheral blood. This is reflected on bone marrow biopsy as marked hypocellularity with an abundance of fat cells and other marrow stroma; aspiration classically produces a "dry tap." Although aplastic anemia is usually idiopathic (no clear cause), it can be triggered by viral infection (eg, hepatitis, HIV), chemical or radiation exposure, or medications (eg, carbamazepine). Patients typically have manifestations of pancytopenia such as severe fatigue and pale mucous membranes (anemia), bleeding/bruising (thrombocytopenia), or infection (eg, leukopenia). No significant extramedullary hematopoiesis occurs (eg, no splenomegaly) because few hematopoietic stem cells continue to function. (Choice A) Acute leukemias (eg, acute myeloid leukemia) are usually associated with a hypercellular marrow with increased blasts. Although anemia and thrombocytopenia may be present, most patients have mild leukocytosis. In addition, blasts would be seen on peripheral smear. (Choice B) Chronic myeloid leukemia, a myeloproliferative neoplasm of granulocytes associated with the BCR-ABL fusion gene, is marked by a hypercellular marrow with increased granulocytes and megakaryocytes. Patients typically have significant peripheral leukocytosis and thrombocytosis; in addition, hepatosplenomegaly is generally present. (Choice D) Myelofibrosis, a chronic hematopoietic neoplasm, is marked by hypocellular marrow with extensive fibrosis. Although pancytopenia is typically present, peripheral blood smear usually shows teardrop-shaped and nucleated erythrocytes; significant extramedullary hematopoiesis also occurs, so dramatic splenomegaly is usually present. (Choice E) Acute promyelocytic leukemia is associated with promyelocytes with Auer rods (rod-shaped cytoplasmic inclusions). This type of acute myeloid leukemia is characterized clinically by disseminated intravascular coagulation (acquired hypercoagulability and bleeding), which is not seen in this patient (normal PT and PTT); immature leukocytes would also be seen on peripheral smear. Educational objective: Aplastic anemia is a form of bone marrow failure due to destruction of multipotent hematopoietic stem cells. It is marked by pancytopenia and profound hypocellularity of the bone marrow with an abundance of fat cells and stroma. Impaired reticulocytosis and an absence of splenomegaly are important features.

A 25-Year-Old Woman Comes to the Office Due to Significant