PMC9593112_01
Left anterior mediastinal mass (yellow circles and arrows): (a) MRI - coronal view; (b) MRI - axial view. A: Anterior; L: Left side; MRI: Magnetic resonance imaging; P: Posterior; R: Right side
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F1
Epithelioid hemangioendothelioma: (a and b) Morphological aspects, HE staining, x400; (c-h) Immunohistochemical profile of studied tumor (x400). CD: Cluster of differentiation; ERG1: Early growth response 1; FLI1: Friend leukemia integration 1 transcription factor; HE: Hematoxylin-Eosin; TFE3: Transcription factor E3
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Tumor cells had a pseudoalveolar arrangement or in solid nests, forming also vascular spaces (Figure 2a), embedded in a fibrous stromal network with areas of hyaline degeneration (Figure 2b). The tumor morphology suggested the diagnosis of EHE that was further enhanced by immunohistochemical (IHC) staining with a panel of long time known and still useful markers indicators of endothelial differentiation, i.e., cluster of differentiation (CD)34, CD31, Friend leukemia integration 1 transcription factor (FLI1) and early growth response 1 (ERG1), which all proved to be positive (Figure 2c,2d,2e,2f). The further immunostaining with transcription factor E3 (TFE3), which was also positive, helped us to define more precisely our tumor as a Yes-associated protein 1 (YAP1)-TFE3 t(X;11)(p11;q22) subtype of EHE (Figure 2g). The calculated index was 5%, indicating a low degree of aggressiveness (Figure 2h).
PET-CT scan: residual metabolically active tissue (yellow circle and arrow). A: Anterior; L: Left side; P: Posterior; PET-CT: Positron emission tomography-computed tomography; R: Right side
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This showed the presence of a small amount of residual metabolically active tissue in the anterior mediastinum (Figure 3).
CT five years after surgery: (a) Coronal view - normal aspect (yellow circle and arrow); (b) Axial view - normal aspect (yellow circle and arrow). A: Anterior; CT: Computed tomography; L: Left side; P: Posterior; R: Right side
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