Bone marrow necrosis in de novo AML.

A 49-year-old man was admitted due to fever, arthralgia, and diarrhea of unknown origin. He had received highly active antiretroviral therapy treatment since 2006, with HIV-RNA being undetectable. Hemogram revealed macrocytic anemia (hemoglobin, 10.5 g/dL; mean corpuscular volume, 101 fL), leukopenia (2.4 G/L; lymphocytes, 2.2 G/L; neutrophils, 0.14 G/L; monocytes, 0.04 G/L; eosinophils, 0.01 G/L; basophils, 0.0 G/L), and normal platelet count (161 G/L). Bone marrow aspirate (panels A and B) and trephine biopsy (kindly provided by Yara Banz, MD, PhD, Institute of Pathology, University of Bern; panels C and D) showed extensive bone marrow necrosis of ;90% (asterisk in panel C; original magnification 35; hematoxylin and eosin [H&E] staining) with no inflammatory infiltrations or granulomatous reaction. Bone marrow aspirate images (May-Grünwald-Giemsa [MGG] staining; original magnification 35 [panel A], 363 [panel B]) were obtained with a Zeiss Axioskop 50 microscope, a Sony Exmor Full HD 3CMOS PMW 10 MD medical camera, Corel PaintShop Pro X4 software (Version 14.2.0.1), and MGG stain. The following were used to obtain bone marrow biopsy images: a Zeiss Axioplan 2 microscope; a Zeiss Axiocam HR camera; AxioVision 40 software (Version 4.8.2); and H&E, Periodic acid–Schiff (PAS), Giemsa, and reticulin stains. For immunohistochemistry, the following were used: myeloperoxidase (MPO), CD33, CD15, CD34, c-kit (CD117), lysozyme, CD68, CD56, terminal deoxynucleotidyltransferase, CD20, CD79a, Pax5, CD3, CD4, CD7, CD10. Flow cytometry (positive staining: CD38, MPO, CD33, CD4, CD15 and partially CD64, lysozyme, CD11b, HLA-DR) and immunohistochemistry (positive staining: MPO, CD33, CD15, lysozyme, HLA-DR, partially c-kit, weakly CD4, partially CD68) revealed an acute myeloid leukemia (AML), most likely of type M4 according to French-American-British (panel C, white arrow labeling blasts; panel D, MPO staining of blasts, original magnification 340) and AML not otherwise specified (World Health Organization 2008) classifications, respectively. No microorganisms or fungi were observed in extensive special stains (PAS, Grocott, Giemsa, Gram, and Ziehl-Neelsen).