A 36-year-old man presents to your office with persistent fever, bleeding gums, and a sore throat. Peripheral blood microscopy findings are shown in the image below. These cells contain structures that would stain positive for which of the following?

Question

A 36-year-old man presents to your office with persistent fever, bleeding gums, and a sore throat.  Peripheral blood microscopy findings are shown in the image below.  These cells contain structures that would stain positive for which of the following?

Quizplus · Accepted Answer

11ec160b_396a_baf0_9249_357b1ce6e21d_MD0001_00 This peripheral blood smear shows myeloblasts, which are large myelogenous cells with abundant basophilic cytoplasm and large nuclei that can be folded or bilobed. Myeloblasts often have a number of coarse rod/needle-shaped intracytoplasmic granules (eg, Auer rods) that stain positive for myeloperoxidase. Auer rods indicate myeloid differentiation. Acute promyelogenous leukemia (APL) is a variant of acute myelogenous leukemia (AML), in which immature cells of myeloid origin are unable to differentiate and mature. They proliferate in the bone marrow and suppress the growth and multiplication of other hematopoietic precursors. The clinical manifestations of APL, such as anemia (fatigue, pallor), thrombocytopenia (petechiae, hemorrhages), and neutropenia (fever, opportunistic infections), result from marrow replacement by leukemic cells. (Choice A) Major basic protein is found in eosinophil granules and helps to defend against parasites. (Choice C) Platelet-derived growth factor receptor mutations play a role in gastrointestinal stromal tumors. (Choice D) Hairy cell leukemia stains positively for tartrate resistant acid phosphatase (TRAP). The neoplastic cells are B lymphocyte precursors and are CD20⁺. Hairy cell leukemia presents with splenomegaly, fatigue and pancytopenia. (Choice E) Terminal deoxynucleotidyl transferase (TdT) is responsible for adding nucleotides to the V, D and J regions of the antibody gene for antibody diversity. It is a marker of immature lymphocytes, both B and T cells. Neoplastic cells in acute lymphoblastic leukemia (ALL) are TdT positive. ALL mainly affects children. Educational Objective: Auer rods are deformed azurophilic granules found in the cytoplasm of myeloblasts that stain positively for myeloperoxidase. Auer rods are found in abundance in AML M3 (acute promyelocytic leukemia).

A 36-Year-Old Man Presents to Your Office with Persistent Fever