A Rare Case of Low-Grade Dedifferentiated Liposarcoma Presenting as a Pharyngeal Polyp: Avoiding a Pitfall With Significant Repercussions

Dedifferentiated liposarcoma is a nonlipogenic sarcoma of variable histological grade that frequently arises in association with a well-differentiated liposarcoma. Dedifferentiation occurs in approximately 10% of well-differentiated liposarcomas and is most commonly encountered in the retroperitoneum. Dedifferentiated liposarcoma of the upper respiratory tract is an extremely rare occurrence. Herein, we report a very rare case of low-grade dedifferentiated liposarcoma of the pharynx that presented as a polyp mimicking a benign process clinically and microscopically. We discuss the relevant molecular findings and review the current literature.

Dedifferentiated Liposarcoma of the Transverse Colon

While liposarcoma is one of the most common soft tissue sarcomas, it is rarely seen within the gastrointestinal tract, and even less frequently seen within the colon. Dedifferentiated liposarcoma is a subtype of liposarcoma, which along with the pleomorphic subtype is considered a high-grade, aggressive tumor; both possess the ability to metastasize and are associated with decreased survival. Despite complete resection, recurrence is common. While surgical excision is the cornerstone of treatment for liposarcoma of the colon, there is no consensus on adjuvant therapies. We present the case of a 66-year-old woman who presented with abdominal pain with rectal bleeding and was found on colonoscopy to have a high-grade dedifferentiated liposarcoma of the transverse colon. She underwent robotic segmental colectomy. Due to absence of nodal involvement or distal metastasis, adjuvant therapy was not administered. On 1-year follow-up, the patient remains disease free.

Establishment and Characterization of NCC-DDLPS4-C1: A Novel Patient-Derived Cell Line of Dedifferentiated Liposarcoma

Dedifferentiated liposarcoma (DDLPS) is a highly malignant sarcoma characterized by the co-amplification of MDM2 and CDK4. Although systemic chemotherapy is recommended for unresectable or metastatic cases, DDLPS is insensitive to conventional chemotherapy, leading to an unfavorable prognosis. Therefore, novel treatment methods are urgently required. Patient-derived cell lines are essential in preclinical studies. Recently, large-scale screening studies using a number of cell lines have been actively conducted for the development of new therapeutic drugs. However, the DDLPS cell line cannot be obtained from public cell banks owing to its rarity, hindering screening studies. As such, novel DDLPS cell lines need to be established. Accordingly, this study aimed to establish a novel DDLPS cell line from surgical specimens. The cell line was named NCC-DDLPS4-C1. NCC-DDLPS4-C1 cells retained copy number alterations corresponding to the original tumors. Further, the cells demonstrated constant growth, spheroid formation, and equivalent invasiveness to MG63 osteosarcoma cells. We also conducted drug screening and integrated the results with those of the previously reported DDLPS cell lines. Consequently, we identified the histone deacetylase inhibitor romidepsin as a novel candidate drug. In conclusion, the NCC-DDLPS4-C1 cell line is a useful tool for the basic study of DDLPS.