case_images: PMC5779770_01
case_images: MRI showing bone marrow cavity and soft tissue lesions on both sides of the middle and lower part of the tibia and the lower end of the femur, in which the middle and lower front edge of the left tibia demonstrates periosteal reaction.
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case_images: PMC5779770_01_medi-97-e9644-g001.jpg
case_images: F1
case_images: General examination was undertaken and magnetic resonance imaging (MRI) scan revealed chronic suppurative osteomyelitis in both legs (Fig. 1).
case_images: Histological findings from debridement sample showing the classic histological features of uniform small round cells with scanty cytoplasm (hematoxylin and eosin,  x 400).
case_images: medi-97-e9644-g002.jpg
case_images: PMC5779770_01_medi-97-e9644-g002.jpg
case_images: F2
case_images: Pathological examination of the debridement sample indicated left tibia ash black tissue at a size of 1.0 x 0.8 x 0.2 cm, and microscopic examination showed uniform small round cells with scanty cytoplasm (Fig. 2).
case_images: (A) Peripheral blood smear showing suspected tumor cells (Wright-Giemsa staining,  x 400). (B) Bone marrow aspirate smear showing diffuse infiltration with a large number of blast-like cells (Wright-Giemsa staining,  x 400). (C) Periodic acid-Schiff staining detected coarse granules, which were considered to be glycogen molecules (x 400).
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case_images: PMC5779770_01_medi-97-e9644-g003.jpg
case_images: F3
case_images: Complete blood count results were as follows: white blood cell counts of 4.11 x 109/L, red blood cell counts of 4.18 x 1012/L, hemoglobin decreased to 92.3 g/L, and platelet counts decreased to 78.10 x 109/L with 24% blast-like cells found in a peripheral blood smear (Fig. 3A). Minimal cytoplasm, vacuolation, irregular microspikes, or pseudopodia at the edge of the cytoplasm were observed, similar to that observed in cases of ES (Fig. 3B). Periodic acid-Schiff staining showed strongly positive granular (Fig. 3C).
case_images: (A) Bone marrow biopsy smear showing diffuse infiltration with a large number of blast-like cells (hematoxylin and eosin,  x 400). (B) The membranes of the blast-like cells showing strong staining for CD99 (x 400). (C) The nuclei of the blast-like cells were positive staining for TdT (x 400).
case_images: medi-97-e9644-g004.jpg
case_images: PMC5779770_01_medi-97-e9644-g004.jpg
case_images: F4
case_images: The bone marrow biopsy (easily aspirated) revealed nucleated cells with marked proliferation and activity, and 90% blast-like cells (Fig. 4A). Immunohistochemistry of the bone marrow biopsy revealed that the blast-like cells were positive for CD10, CD34, and CD99 (Fig. 4B), and were negative for CD2, CD3, CD20, CD38, CD117, and CD138. TdT (Fig. 4C) and PAX5 and negative for NSE.