Figure 1. Diagnostic findings in the primary and relapse tumors. (A, B) Histology of core biopsies in the primary tumor. (A) Hematoxylin and eosin (HE) staining showing malignant small blue round cell tumor with hyperchromatic, immature, rounded cells with scant cytoplasm growing in a partly solid and partly trabecular pattern in a desmoplastic stroma. (B) Positive perinuclear cytoplasmic and focally dotlike Desmin staining. (C, D) Histology of open biopsies in the second relapse, scalp tumor. (C) HE staining showing a malignant small blue round cell tumor with oval to rounded cells with hyperchromatic nuclei and scant cytoplasm in a desmoplastic stroma. (D) Desmin immunostaining with perinuclear cytoplasmic pattern. (E) Visualization of RNA sequencing results from the soft tissue sarcoma, showing the EWSR1::WT1 fusion transcript. The upper part of the figure displays the fusion partners with their chromosomal localization (GRCh38) and orientation, while the lower part visualizes the predicted fusion transcript and the retained exons. All histology figures are presented at a magnification of 40×.