Clinical significance of MDM2 protein expression and gene amplification in atypical lipomatous tumour/well-differentiated liposarcoma / 临床与实验病理学杂志

Purpose This study was to investigate the clinical significance of MDM2 protein expression and gene amplification in atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDL).Methods MDM2 protein expression and gene amplification were detected by immunohistochemistry of EliVision two-step method and fluorescence in situ hybridization (FISH) in 58 cases of ALT/WDL.Results Immunohistochemical staining showed that the positive rate of MDM2 was 79.3％,MDM2 gene amplification rate by FISH assay was 96.5％.There was statistically significant differences between immunohistochemistry and FISH (P ＜ 0.05).Conclusion MDM2 protein expression and MDM2 gene amplification provide the basis for diagnosis of ALT/WDL.However,a positive rate of MDM2 by immunohistochemistry is nearly 80％,so we recommand to carry out immunohistochemical MDM2 protein detection in most conditions without FISH which can help in the diagnosis of most cases of ALT/WDL.

Sclerosing liposarcoma of the anterior mediastinum: An unusual case.

Liposarcomas are extremely rare in the mediastinum. Patients usually present late due to the compressive effect of the tumor on the adjacent structures. Severity of the symptoms depend mainly on the size of the tumor and the structure it infiltrates. Well differentiated slow growing liposarcomas are the most common ones in the mediastinum followed by dedifferentiated and poorly differentiated ones. These tumors have bad prognosis because of incomplete surgical excision due to its inaccessible location. Hence these patients should be kept under close follow up because of high recurrent rates. Here we are presenting a rare case of anterior mediastinal sclerosing liposarcoma in a 77 year old male.

Overexpression and amplification of Murine double minute 2 as a diagnostic tool in large lipomatous tumor and its correlation with Ki67 proliferation index: An institutional experience.

Context: Well-differentiated liposarcoma (WDLPS) is the most common type of liposarcoma and sometimes can be diffi cult to distinguish from large lipoma due to the similar morphology. Aims: This study proposed to evaluate the expression and amplifi cation of Murine double minute 2 (MDM2) gene and determine its correlation with Ki67 proliferation index. Settings and Design: This study used cross-sectional design. Materials and Methods: This study enrolled 37 cases of lipomatous tumors with >5 cm in size. Eighteen cases of WDLPS and 19 cases of lipoma were stained for MDM2 and Ki67 immunohistochemistry, followed by MDM2 in situ hybridization in 12 selected cases. Statistical Analysis Used: MDM2 overexpression and amplification status for both groups were compared using Chi-square test, with the alternative of Fisher’s exact test. Correlation test between MDM2 overexpression and clinical characteristics with the Ki67 proliferation index were performed using Pearson’s test with the alternative of Spearman’s rho test. Results: MDM2 overexpression was detected in all WDLPS cases and in 3 (16%) of lipoma cases with signifi cance difference (P = 0.000), whereas MDM2 amplifi cation was found in all WDLPS and in 1 of lipoma cases (P = 0.200). There was a strong correlation between MDM2 overexpression and higher Ki67 proliferation index (r = 0.645, P = 0.000). Conclusion: Evaluation of MDM2 overexpression can be used as a useful adjunct to differentiate WDLPS from large lipoma and seems to be related with Ki67 proliferation index.

Critical histopathological analysis of 25 dedifferentiated liposarcomas, including uncommon variants, reviewed at a Tertiary Cancer Referral Center.

Background: De-differentiated liposarcomas (DDLSs) are uncommon tumors with a wide histopathological spectrum. Materials and Methods: Over an 8-year period (2003-2011), 25 DDLSs, after review, were critically analyzed for histopathological features. Results: Twenty-five tumors, in 14 men and 11 women (M: F = 1.2:1), with age range of 22-88 years (mean, 53.9), occurred in retroperitoneum (14) (56%), thigh (3) (12%), paratesticular region (3) (12%), chest wall (2) (8%), leg (1) (4%), shoulder (1) (4%), and groin (1) (4%). Tumor size (21 tumors) varied from 7.5 to 25 cm (mean, 17.5). Histopathologically, DD component was high grade in 19 (76%) and low grade in 6 (24%) tumors. Whereas the most common WD component was adipocytic type; the most common DD component was pleomorphic sarcomatous (13) (52%), followed by myxofibrosarcomatous (MFS)-type (6) (24%). Low-grade DD components included MFS (2), fibrosarcoma (2), myogenic/myofibroblastic type (1), and IMFT-type (1). Three tumors displayed meningothelial-like whorls and metaplastic bone formation. Heterologous elements, noted in 11 (44%) tumors, included bone (8) and rhabdomyoblastic differentiation (2). Two tumors displayed homologous differentiation, reinforced with MDM2 staining. S100-P was diffusely positive in WD components (5/7) and focally in DD components (2/9). All patients were treated with surgery, including 10, who underwent adjuvant radiotherapy. Outcomes (16 patients, 64%), over 1-48 months included 10 patients free of disease, 4 died of disease, and 2 patients alive with disease. Conclusions: This study forms the largest documentation of DDLSs, including its wide histopathological spectrum, from our country. Rare cases overlap with pleomorphic liposarcoma. S100-P and MDM2 are useful in substantiating adipocytic differentiation, especially in selected cases. Analysis of adequate tumor sections is vital for correct identification of a DDLS. Surgical excision with adjuvant RT forms optimal treatment.

Dedifferentiated liposarcoma of the retro-peritoneum: Histologically low-grade type.

A dedifferentiated liposarcoma of the retro-peritoneum of a 45-year-old female is described in this case report. It showed dedifferentiation into a histological low-grade type and thus defies the traditional definition of dedifferentiated liposarcoma. The excised specimen was a huge, multi-nodular encapsulated mass surrounding the kidney and infiltrating into it. The mass showed a dedifferentiated focus different in color from the surrounding tumor and containing areas of necrosis and hemorrhage. The sections from the dedifferentiated part of the tumor appeared predominantly as benign spindle cell component on histology but the tumor was infiltrating into the kidney. Hence, a close and long-term follow-up is expected in such cases though they look benign. In the retro-peritoneum, a lipoma-like well-differentiated liposarcoma with spindle cell component, like the present tumor, which shows dedifferentiation, should not be overlooked.