Askin Tumor in an Adult: Recognizing a Rare Chest Wall Presentation of Ewing Sarcoma

Figures

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  Figure 1. Axial (A), coronal (B), and sagittal (C) CT images from September 2023 demonstrate interval enlargement of the lesion with a more heterogeneous appearance and increased soft tissue volume (yellow arrows), raising concern for a neoplastic process.

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  Figure 2. Axial (A), coronal (B), and sagittal (C) CT images from June 2020 show a small, well-defined soft tissue lesion in the right posterolateral chest wall (yellow arrows), initially presumed to represent a benign process such as a lipoma or inclusion cyst.

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  Figure 3. Axial MR imaging of the chest wall lesion (yellow arrows). (A) T1-weighted in-phase and (B) out-of-phase sequences demonstrate no signal drop, indicating the absence of microscopic fat.

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  Figure 4. Multiplanar MRI of the thorax demonstrating a right posterolateral chest wall mass (yellow arrows). (A, C, E) Pre-contrast T1-weighted images in axial (A), coronal (C), and sagittal (E) planes show a well-defined chest wall lesion isointense to muscle. (B, D, F) Corresponding post-contrast fat-suppressed T1-weighted images in axial (B), coronal (D), and sagittal (F) planes reveal heterogeneous enhancement of the mass.

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  Figure 5. (A) The neoplasm after neoadjuvant therapy, demonstrating extensive necrosis and replacement by fibrosis. At higher magnification, the viable areas (B) consist of uniform small round cells with scant eosinophilic cytoplasm and indistinct cytoplasmic membranes.

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  Figure 6. Axial non-contrast CT from February 2025 demonstrates postoperative changes with the absence of the mass and no evidence of local recurrence (yellow arrow).