case_images: PMC9148177_01
case_images: The morphology of hematoxylin-eosin staining mediastinal mass, including primary (A-F) and metastatic GCT (G-I). The primary mass contained seminoma (10%) and immature teratoma (90%) components. The seminoma cell was pleomorphic with abundant cytoplasm and distributed in clusters ((C-D), 200x and 400x). The components of immature teratoma mainly included immature neural tube ((A-B), 200x and 400x), cartilage ((E), 200x), and glands ((F), 400x). The metastatic mass was a mainly extensive deposition of osteoid connective tissue, surrounded by atypical epithelioid cells ((G), 200x, and (H-I), 400x). The neoplastic cells, featured with increased nuclear-to-cytoplasmic ratio and abnormal chromatin distribution, were arranged in irregular lacunar (H) and adenoid structures (I). The red or black triangles pointed to the corresponding structure. GCT, germ cell tumor.
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case_images: He underwent a complete surgical tumorectomy, and the histopathology showed a malignant mixed germ cell tumor encompassing seminoma and immature teratoma tumor components (Figure 1A-F). He then underwent pneumoresection, and the pathological result revealed a single immature teratoma (Figure 1G-I).
case_images: The features of morphology and chemical staining in the case. The morphology of Wright-Giemsa-stained marrow smear (A-C) and peripheral blood smear (D) was shown, 1000x, and the red triangle pointed to atypical mast cells. The results of chemical staining were negative for POX (E), NAS-DCE (F), and NSE (G), and was positive for Toluidine Blue (H-I), 1000x. The red triangles pointed to the positive cells in the corresponding staining.
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case_images: AS-D chloroacetate esterase staining (NAS-DCE), except for toluidine blue staining (Figure 2). An analysis of the BM aspirate via multiparameter flow cytometry revealed that abnormal cells were positive for CD45, CD117, CD13, CD33, and CD9 but weakly positive for CD2 and CD22, and negative for CD16, CD7, kappa, lambda, CD19, CD38, HLA-DR, CD35, CD65, CD15, CD11b, CD123, CD79a, CD10, CD25, CD34, and MPO (Figure 3).
case_images: Multi-color flow cytometry analysis of cell surface markers of marrow mononuclear cells. Partial markers of the detected were presented. The cluster of cells colored in red indicated the leukemic cells.
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case_images: AS-D chloroacetate esterase staining (NAS-DCE), except for toluidine blue staining (Figure 2). An analysis of the BM aspirate via multiparameter flow cytometry revealed that abnormal cells were positive for CD45, CD117, CD13, CD33, and CD9 but weakly positive for CD2 and CD22, and negative for CD16, CD7, kappa, lambda, CD19, CD38, HLA-DR, CD35, CD65, CD15, CD11b, CD123, CD79a, CD10, CD25, CD34, and MPO (Figure 3).
case_images: Sanger sequencing of genomic PCR products of bone marrow mononuclear cells. The detailed information of 4 genetic mutations, including TP53, FLT3, SETBP1, and JAK3, was written below the corresponding peak diagram. The black arrow pointed to the mutant base. PCR, polymerase chain reaction.
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case_images: Table 1. Four mutated genes were sequenced again via Sanger sequencing (Figure 4). The PCR primers that were used are listed in Supplemental Table 1. The bone marrow biopsy revealed atypical cells that were mainly oval and short spindle cells distributed in clusters and eosinophilic by hematoxylin-eosin (HE) staining, accounting for 80% of the nucleated cells.
case_images: Morphologic and immunohistochemical features of the case. Marrow biopsy showed the architecture was diffusely infiltration by clusters of oval and short spindle cells ((A and B), 200x and 400x). The neoplastic cells were positive for CD117 (C), but almost all negative for MPO (D), CD25 (E), and CD34 (F), 200x.
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case_images: Immunohistochemical staining confirmed positivity for CD117 and negativity for MPO, CD25, and CD34 (Figure 5). 