Mediastinal liposarcoma: a rare visceral mediastinal tumour

Mediastinal tumours and pseudo-tumours: a comprehensive review with emphasis on multidisciplinary approach

The diagnosis of a mediastinal mass may be challenging for clinicians, since lesions arising within the mediastinum include a variety of disease entities, frequently requiring a multidisciplinary approach. Age and sex represent important information, which need to be integrated with imaging and laboratory findings. In addition, the location of the mediastinal lesion is fundamental; indeed, we propose to illustrate mediastinal diseases based on the compartment of origin. We consider that this structured approach may serve as hint to the diagnostic modalities and management of mediastinal diseases. In this review, we present primary mediastinal tumours in the evolving context of new diagnostic and therapeutic tools, with recently described entities, based on our own experience with >900 cases encountered in the past 10 years.

Given the mediastinal anatomical heterogeneity, the correct positioning of mediastinal lesions becomes primal, in order to first establish a clinical suspicion and then to assist in planning biopsy and surgical procedurehttps://bit.ly/3p0gsk3

Sarcomas of the mediastinum with epithelioid morphology

While soft tissue sarcomas typically have a spindled or pleomorphic appearance, a subset of malignant soft tissue neoplasms can have a prominent epithelioid morphology. In complex anatomic sites such as the mediastinum, such tumors can often be mistaken for a carcinoma or mesothelioma. Frequent expression of cytokeratin staining can further confound the diagnostic process and familiarity with these entities can help prevent an erroneous diagnosis. Particular entities that have been reported to occur in the mediastinum with such features include dedifferentiated liposarcoma, pleomorphic liposarcoma, malignant peripheral nerve sheath tumor, synovial sarcoma, SMARCA4-deficient thoracic sarcoma, alveolar soft part sarcoma and clear cell sarcoma. Many of these tumors exhibit unique clinical, genetic, molecular or immunohistochemical features which allow for accurate characterization. For example, pleomorphic liposarcoma contains bizarre appearing lipoblasts and dedifferentiated liposarcoma exhibits MDM2 gene amplification that is typically confirmed by fluorescence in-situ hybridization. Malignant peripheral nerve sheath tumor will often arise in association with a nerve or neurofibroma. Synovial sarcoma consistently exhibits rearrangements involving the SS18 gene and SMARCA4-deficient thoracic sarcoma shows loss of SMARCA4 staining in the tumor cells. Alveolar soft part sarcoma demonstrates an ASPL-TFE3 fusion transcript. Clear cell sarcoma often shows an EWSR1-ATF1 fusion transcript. When encountering a sarcoma of the mediastinum with epithelioid features, familiarity with these and other characteristics can help insure a correct diagnosis.