Dedifferentiated Liposarcoma With Myofibroblastic Differentiation

Abstract

Context.— Liposarcoma is divided into myxoid, pleomorphic, well-differentiated, and dedifferentiated subtypes. Dedifferentiated liposarcoma displays the greatest histomorphologic diversity, including a subset with myofibroblastic differentiation that shares similarities with a spectrum of reactive, benign, and malignant soft tissue lesions. Misdiagnosis may lead to deleterious consequences, as dedifferentiated liposarcoma differs significantly in its prognosis and treatment from its mimics. Objective.— To review the clinicopathologic, immunohistochemical, and molecular features of the myofibroblastic variant of dedifferentiated liposarcoma as well as the key distinguishing features from its mimics. Data Sources.— Review of pertinent literature on major features and current understanding of dedifferentiated liposarcoma with myofibroblastic differentiation. Conclusions.— The myofibroblastic variant of dedifferentiated liposarcoma is an uncommon and underrecognized sarcoma with several important differential diagnoses, and likely represents the major subset of aggressive retroperitoneal tumors that may have been misdiagnosed as desmoid-type fibromatosis, inflammatory myofibroblastic tumor, or another type of sarcoma in the past.

Increasing Incidence of Liposarcoma: A Population-Based Study of National Surveillance Databases, 2001–2016

“…This is consistent with other liposarcoma studies [31]. In general, well-differentiated liposarcoma has a low probability of metastasis, and therefore, treatment options such as marginal excision will often yield good results [32]. However, well-differentiated tumors are also known for having a high rate of local recurrence [32].…”

“…In general, well-differentiated liposarcoma has a low probability of metastasis, and therefore, treatment options such as marginal excision will often yield good results [32]. However, well-differentiated tumors are also known for having a high rate of local recurrence [32]. Patients with well-differentiated tumors located in areas where excision is no longer possible, such as retroperitoneum, have lower survival (63.9%).…”

“…Mutations of recurrent well-differentiated tumors can sometimes result in a change in tumor histology. For example, dedifferentiated tumors contain patterns of both well-differentiated and other higher grade non-lipogenic elements [32]. Current estimations of more aggressive dedifferentiated nodules arising from recurrent well-differentiated tumors are around 10% [34].…”

“…Current estimations of more aggressive dedifferentiated nodules arising from recurrent well-differentiated tumors are around 10% [34]. Five-year survival rates for dedifferentiated tumors can be as low as 20% to 40% [32]. In our data, the 5-year survival was higher, with approximately 58% for the dedifferentiated sub-type, however, compared to the other histological types of liposarcoma where survival ranged from 96% (well-differentiated) to 64% (pleomorphic), dedifferentiated tumors are the most deadly.…”

“…In our data, the 5-year survival was higher, with approximately 58% for the dedifferentiated sub-type, however, compared to the other histological types of liposarcoma where survival ranged from 96% (well-differentiated) to 64% (pleomorphic), dedifferentiated tumors are the most deadly. These statistics are not surprising given that dedifferentiated tumors are often higher grade, heterogeneous in nature, and have limited response to current therapy [32,35]. For those diagnosed with dedifferentiated tumors of the retroperitoneum, even if surgical resection is a viable treatment option, recurrence occurs in over 80% of the patients, with 30% to metastatic sites [35].…”