Myxoid liposarcoma with nuclear pleomorphism: a clinicopathological and molecular study

In this study, we conducted an in-depth investigation of four MLS tumors that demonstrated nuclear pleomorphism in three patients. These cases accounted for 2.1% of 142 patients with MLS. All patients were male aged 26, 33, and 49 years. Nuclear pleomorphism was observed in both primary and metastatic tumors in one patient, a primary tumor in one patient, and a metastatic tumor in another patient. Pleomorphism was severe in three tumors and moderate in one. Histology resembled that of dedifferentiated liposarcoma with myxoid features, pleomorphic liposarcoma with myxoid features, or myxoid pleomorphic liposarcoma in two tumors, pleomorphic sarcoma with focal cartilaginous and rhabdomyoblastic differentiation in one tumor, and epithelioid pleomorphic liposarcoma in one tumor. All tumors harboredFUS::DDIT3 fusions and immunohistochemically expressed DDIT3. All tumors hadTP53 mutations, whereas previous specimens with uniform cytology from the same patients lackedTP53 mutations. One tumor showedRB1 deletion and complete loss of Rb expression, which was unclassifiable using DNA methylation-based methods. The rare occurrence of nuclear pleomorphism is underrecognized in MLS and increases the complexity to the diagnosis of liposarcoma.DDIT3 evaluation can be liberally considered in liposarcoma assessment even in the presence of nuclear pleomorphism.
Source: Virchows Archiv - Category: Pathology Source Type: research