Answer and Discussion of Quiz Set: K-001

1.    Extramedullary hematopoiesis (EMH) is a major differential diagnosis of myelolipoma. Which of the following is not true about EMH?

A.  EMH is typically multiple rather than solitary. Myelolipoma is often solitary.

B.  EMH is usually secondary to severe anemia and various myeloproliferative disorder.

C.  EMH often form a mass and the adrenal gland is often involved.

D.  EMH is associated with splenomegaly and hepatomegaly.

E.  EMH is often associated with skeletal disorders.

Answer and Discussion: The answer is (C). EMH does not always forma a mass. In some occasions, EMH can form a mass and compress the surrounding organ but the adrenal gland is not the most commonly affected. Click here to see a case of extramedullary hematopoiesis with compression of the spinal cord. EMH is most often seen in paraspinal regions of the thorax, spleen and liver leading to hepatosplenomegaly, and other locations including the adrenal gland, intestine, and breast. Most myelolipoma arises in the adrenal gland. However, then can also arise in other location. In those cases, the possibility of EMH should be considered and clinical history would be useful in making the correct diagnosis.