PMC10467293_01
Coronal T1-WI and coronal and axial T1 with fat saturation after Gadolinium, showing the soft-tissue mass (arrow) within the tibialis anterior muscle in heterogenous hyposignal T1 (similar to skeletal muscle) with heterogenous striking enhancement after Gadolinium administration.
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T1 heterogeneous low signal intensity (similar to skeletal muscle) with heterogenous but striking enhancement after Gadolinium administration (Figure 1). These findings were associated with multiple bilateral intramedullary osseous lesions of both the tibial and femoral bones. These lesions presented with an ill-defined limit, a heterogenous T2 hyper signal, and a T1 hypo signal heterogeneously enhanced after Gadolinium (Figure 2).
Coronal STIR (a and b), coronal (c) and axial T1-WI with fat saturation after Gadolinium (d and e), showing bilateral intramedullary osseous lesions of both the tibial (blue arrow) and femoral bones (red arrow), heterogeneously enhanced after Gadolinium.
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T1 heterogeneous low signal intensity (similar to skeletal muscle) with heterogenous but striking enhancement after Gadolinium administration (Figure 1). These findings were associated with multiple bilateral intramedullary osseous lesions of both the tibial and femoral bones. These lesions presented with an ill-defined limit, a heterogenous T2 hyper signal, and a T1 hypo signal heterogeneously enhanced after Gadolinium (Figure 2).
(a) Hematoxylin and eosin, 20x magnification. (b) Hematoxylin and eosin, 40x magnification. Histopathological examination of the soft-tissue mass showing sheets of monotonous small round blue cells associated to hyperchromatic nuclei and absence of nucleoli with some of these cells forming pseudorosettes.
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The latter showed marked tumor necrosis with high cellularity, composed of round uniform small cells, oval nuclei, and scanty lacy cytoplasm (Figure 3).
Panels of immunohistochemical tests (40x magnification), showing the neoplastic cells diffusely positive for CD99 (a) and for vimentin (b).
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There were some rare pseudorosettes (the equivalent of neuroectodermal differentiation) and immunopositivity for CD99 (diffuse-membranous) and Vimentin (Figure 4).
Axial chest CT (lung window) axial and sagittal reconstruction showing a nodule in the right Fowler (blue arrow) and two nodules of the antero-medial segment of the left lower lobe.
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The patient then underwent a chest and abdomen computed tomography (CT)-scan which showed pulmonary nodules located in the right Fowler segment and the anteromedial segment of the inferior left lower lobe (Figure 5).