Can HMGI-C be used as an aid with MDM2 and CDK4 to differentiate liposarcoma subtypes from their mimics?

Expression of FRS2 in atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma: an immunohistochemical analysis of 182 cases with genetic data

Background

The fibroblast growth factor receptor substrate 2 (FRS2) gene is located close to MDM2 and CDK4 within the 12q13-15 chromosomal region. FRS2 gene was recently found to be consistently amplified in atypical lipomatous tumor (ALT)/well-differentiated liposarcoma (WDL) and dedifferentiated liposarcoma (DDL), suggesting the detection of FRS2 amplification could be a diagnostic tool for ALT/WDL/DDLs. However, the expression of FRS2 protein and diagnostic value of FRS2 immunohistochemistry (IHC) has not been evaluated in a large cohort of ALT/WDL/DDLs.

Methods

A SNOMED search of hospital surgical pathology files from January 2007 to July 2020 identified 182 ALT/WDL/DDLs with available materials. FRS2 fluorescence in situ hybridization (FISH) and IHC were performed on 182 ALT/WDL/DDLs and 64 control samples. The expression of FRS2 was also compared with that of classic immunomarkers (MDM2 and CDK4) of this tumor entity.

Results

This study included 91 ALT/WDLs and 91 DDLs. The FISH results showed 172 of 182 (94.5%) cases were FRS2-amplified, and 10 cases were FRS2-nonamplified. Immunostaining results showed 171 (94.0%) ALT/WDL/DDLs were positive for FRS2 and 11 cases (6.0%) were FRS2-immunonegative. In 172 FRS2-amplified cases, 166 (96.5%) were FRS2-immunopositive, and 6 (3.5%) were negative. Among 10 FRS2-nonamplified ALT/WDL/DDL cases, 5 cases were FRS2-immunonegative, and 5 tumors displayed 1+ staining for this marker. In 64 control cases, none of them exhibited FRS2 amplification. Forty-seven (73.5%) control cases were negative for FRS2 immunostaining, while 17 cases (26.5%) were FRS2-immunopositive. Fifteen of these false positive samples (15/17, 88.2%) showed 1+ positivity and only 2 cases (2/17, 11.8%) displayed 2+ positivity. In ALT/WDL/DDLs, the sensitivity of FRS2 immunostaining was slightly lower than MDM2 (FRS2 vs. MDM2: 94.0% vs 100.0%) and CDK4 (FRS2 vs. CDK4: 94.0% vs 97.0%). However, the specificity of FRS2 (73.5%) was slightly higher than that of MDM2 (67.8%) and CDK4 (64.4%).

Conclusion

This study indicated that FRS2 IHC had relatively good consistency with FRS2 FISH, suggesting that FRS2 immunostaining could be utilized as an additional screening tool for the diagnosis of ALT/WDL/DDL. It must be emphasized that MDM2/CDK4/FRS2 especially MDM2 FISH remains the gold standard and the most recommended method to diagnose this entity.

Retroperitoneal Tumor: A Silent Trespasser - Role of Image-Guided Fine-Needle Aspiration Cytology with Histopathological Correlation in Early Diagnosis

OBJECTIVE

Retroperitoneal lesions present a great diagnostic challenge. Here we analyze the spectrum of retroperitoneal lesions and the utility of cytohistopathological correlation in early diagnosis.

STUDY DESIGN

This 7-year study was undertaken in 338 patients with a retroperitoneal mass (kidney/adrenal/ pancreas/retroperitoneal lymph node, or soft tissue origin). In a prospective analysis, 81 patients underwent image-guided fine-needle aspiration cytology (FNAC) and 70 of the 81 underwent Tru-cut biopsy/histopathological evaluation. Clinical, radiological, and pathological details of 257 patients were retrieved from institutional records for retrospective analysis. A total of 119 patients, i.e., 70 in the prospective analysis and 49 in the retrospective analysis, had cytohistopathological correlation.

RESULTS

Of the 338 cases, 88.4% were malignant (n = 274), 2.6% were benign (n = 8), 9% were nonneoplastic (n = 28), and 9% were inadequate (n = 28). Most were renal in origin (n = 106; 34.2%), followed by retroperitoneal soft tissue (n = 96; 31%). The most common nonneoplastic lesion was tubercular lymphadenitis (42.85%) and the most common benign lesion was paraganglioma (42.85%). The most common malignancy was renal cell carcinoma (21.16%), followed by Wilms' tumor (13.86%). In infancy and early childhood, Wilms' tumor, neuroblastoma, and germ cell tumor were the most common malignancies, while in middle age it was renal cell carcinoma, followed by pancreatic adenocarcinoma, and in the elderly age group it was metastatic carcinoma. Most malignancies were noted in the 5th to 6th decades. The overall sensitivity, specificity, and diagnostic accuracy of image-guided FNAC was 98.02, 72.22, and 94.12%, respectively.

CONCLUSION

Image-guided FNAC is highly sensitive and specific for early diagnosis of an otherwise silent retroperitoneal mass. It saves patient from meticulous surgical procedures for diagnostic reasons and allows more rational planning of management. Knowledge of the distribution of tumors by age group helps to narrow down differential diagnoses.

Retroperitoneal liposarcoma: current insights in diagnosis and treatment

Retroperitoneal liposarcoma (RLS) is a rare, biologically heterogeneous tumor that present considerable challenges due to its size and deep location. As a consequence, the majority of patients with high-grade RLS will develop locally recurrent disease following surgery, and this constitutes the cause of death in most patients. Here, we review current insights and controversies regarding histology, molecular biology, extent of surgery, (neo)adjuvant treatment, and systemic treatment including novel targeted agents in RLS.