Answer and Discussion of Quiz Set: K-001

2.    A 60 year-old pale appearing woman presented with the chief complain of malice, lost of appetitie, fever and petechiae. Physical examination revealed a bluish subcutaneous swelling on her inner thigh. A biopsy was performed and revealed immature atypical cells infiltrating and admixed with the adipocytes. No erythoid cells or megakaryocytes are noted. The atypical cells contain Auer rods and CD34 positive granules and negative for CD20, Pax5 and pancytokeratin. Which of the following is the most likely diagnosis?

A.  Myeloid sarcoma.

B.  Non-Hodgkins B-cell lymphoma.

C.  Dedifferentiated liposarcoma.

D.  Extrramedullary hematopoiesis.

E.  Undifferentiated high grade sarcoma.

Answer and Discussion: The answer is (A). The Auer rods and CD34 positive cytoplasmic granules in atypical cells are features of myeloid sarcoma. Her constitutional symptoms and signs are also compatible with leukemia. Patient with a diagnosis of acute leukemia may show soft tissue infiltration and these collections are known as myeloid sarcoma. The negative result of CD20 in the light of Auer rods and CD34 positive cytoplasmic granules rule out Non-Hodgkin's B-cell lymphoma. Dedifferentiated liposarcoma is often associated with a lower grade liposarcoma and will not contain Auer rods. Extramedullary hematopoiesis is a thought but they should not look atypical, should not have Auer rods or CD34 positive cytoplasmic granules, and often contains erythoid precursor cells and megakaryocytes. Undifferentiated high grade sarcoma should not contain Auer rods or CD34 positive cytoplasmic granules.