Morphologic-cytogenetic analysis of dedifferentiated liposarcomas with an extensive misleading leiomyosarcomatous component

Focal Divergent Chondrosarcomatous Differentiation in a Primary Pleomorphic Liposarcoma and Expression of Transforming Growth Factor 3

A rare case of primary pleomorphic liposarcoma of the thigh with a myxoid component, in which divergent differentiation to a well-differentiated chondrosarcoma was focally present, is described. Presence of heterologous elements has mainly been recognized in the context of dedifferentiated liposarcomas. Few cases of benign mesenchymal tissue have also been reported in well-differentiated and myxoid liposarcomas, while divergent sarcomatous differentiation in liposarcomas appears to be also rare in the absence of dedifferentiation. Positive immunostaining of transforming growth factor-n, which seems to play a role in the formation of bone and cartilage, was demonstrated in our case. Review of the existing literature on the subject has been carried out.

Retroperitoneal liposarcoma with leiomyosarcomatous differentiation

We herein describe a 60-year-old Japanese man with a giant retroperitoneal liposarcoma undergoing leiomyosarcomatous differentiation. He was admitted to our hospital because of a 5-month history of dysphagia and abdominal distention. Abdominal computed tomography showed a giant tumor that occupied the entire retroperitoneal space. The majority of the mass was lipomatous and low density; both a heterogenous and solid mass were also present. A giant retroperitoneal liposarcoma was diagnosed, and tumor resection was performed. At surgery, the tumor was mostly isolated from the retroperitoneum and other organs. Histopathologically, the tumor comprised well-differentiated and dedifferentiated liposarcoma with heterologous differentiation of the leiomyosarcomatous components, which is a rare phenomenon in liposarcoma. The patient was alive 3 years after the first treatment, although he has had 3 local recurrences (approximately one recurrence yearly) and has been treated by repeated resection and radiotherapy.

Dedifferentiated Liposarcoma of the Retroperitoneum with Extensive Leiomyosarcomatous Differentiation and beta-Human Chorionic Gonadotropin Production

Dedifferentiated liposarcomas may display a variety of “heterologous” lines of differentiation, including osseous, vascular, skeletal, and/or smooth muscular. There have been six previously reported examples of leiomyosarcomas associated with high levels of serum human chorionic gonadotropin (hCG) production, comprised of cases originating from the retroperitoneum, spermatic cord, small intestine, and uterus. This report describes the first example of a dedifferentiated liposarcoma that combined both of the aforementioned features: extensive heterologous (leiomyosarcomatous) differentiation and β-hCG production (maximum serum levels 1046 mIU/ml, reference <5 mIU/ml). The tumor, which originated in the retroperitoneum in the region of the right kidney, was rapidly progressive and ultimately fatal within three months of its diagnosis. In addition to characteristic morphologic features, lipogenic and smooth muscle differentiation were confirmed with immunohistochemical stains for MDM2 and smooth muscle actin, respectively. The tumor also displayed diffuse immunoreactivity for β-hCG in both primary and metastatic sites. This case further expands the clinicopathologic spectrum of lipogenic tumors.

Dedifferentiated Liposarcomas With Divergent Myosarcomatous Differentiation Developed in the Internal Trunk

Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas.