Poorly-differentiated and undifferentiated sarcomas of the mediastinum: a bag of tricks

Figures

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  Figure 1. Algorithmic approach to the diagnosis of a mediastinal pleomorphic neoplasm. The careful review of clinical data (patient history, presenting symptoms and signs, radiology) is of paramount importance. If clinical data suggest a specific diagnosis of a non-sarcomatous or a benign mesenchymal neoplasm this should be confirmed with ancillary studies. In addition, even if clinical data are suggestive for a diagnosis of sarcoma, more common non-sarcomatous neoplasms should be ruled out. Finally, to conclude for a diagnosis of undifferentiated pleomorphic sarcoma (UPS) other sarcomas must be ruled-out.

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  Figure 2. The patient, a young adult male, presented with a mediastinal multinodular infiltrative mass at CT scans (upper left panel; main image: sagittal view; insert: frontal view). The lesion was characterized by high-grade epithelioid and pleomorphic morphology and was diagnosed, elsewhere, as undifferentiated pleomorphic sarcoma. A complete immunohistochemical analysis showed a positive staining for CD45: a finding consistent with a diagnosis of myeloid sarcoma. Upper right panel: haematoxylin and eosin (H&E), ×100; lower left panel: H&E, ×400; lower right panel: ×400.

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  Figure 3. The patient, a 57 years old male, showed a posterior mediastinal mass with a high SUVmax (6.52) at a CT-PET scan during a work up for pulmonary embolism. A biopsy was performed and the neoplasm had spindle cell morphology with cellulated areas (H&E, ×400); immunostains were consistent with a schwannoma (×200). On the surgical specimen areas with some degree of pleomorphism were evident (lower left panel; H&E, ×200).

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  Figure 4. Left pictures show an intimal sarcoma of the heart with the involvement of the right pulmonary artery (upper panel, MRI frontal view, arrowheads). Pictures on the right show dedifferentiated liposarcomas a partly adipose neoplasm filling and expanding the mediastinum (upper panel, asterisk). Both lesions show a pleomorphic morphology (lower panels; ×200), positivity to MDM2 and—variably—to myogenic markers at immunohistochemistry, and MDM2 amplification at FISH analysis. The differential diagnosis rests on accurate integration of pathological findings with radiological data and clinical information.