Improved Biopsy Accuracy in Retroperitoneal Dedifferentiated Liposarcoma

BACKGROUND

Biopsy sensitivity in retroperitoneal dedifferentiated liposarcoma (DDLPS) is variable. Patients with grade 3 DDLPS face a significant risk of metastatic disease and may potentially benefit from neoadjuvant therapy, making highly accurate pretherapy diagnosis essential. Our study aimed to establish whether diagnostic sensitivity could be improved by targeting solid areas of tumor on percutaneous biopsy.

METHODS

Between 2016 and 2019, data on patients with suspected primary retroperitoneal sarcoma who underwent a biopsy were collected, and diagnostic accuracy was calculated. These data were compared with our previously reported series from 2005 to 2016. For DDLPS tumors, comparisons were then made between biopsies that targeted the solid component and those that did not.

RESULTS

Data were available for 121 patients in the current series and 238 from the previous study. The proportion of biopsies returning a histological subtype concordant with postoperative pathology was 83% in the current series, marking a significant improvement over our previous study (67%, p = 0.001). For diagnosis of DDLPS, biopsy sensitivity improved from 40 to 74% (p < 0.001), with an increase from 13 to 50% (p = 0.006) where grade 3 DDLPS was treated as a separate disease. Within the current series, targeted biopsy yielded a sensitivity of 100% for identifying DDLPS, compared with 10% in nontargeted biopsy (p < 0.001).

CONCLUSION

Systematic targeting of solid areas of tumor within suspected retroperitoneal liposarcoma has improved sensitivity for detection of both DDLPS and grade 3 DDLPS on biopsy. This approach minimizes the risk of underdiagnosis of patients with DDLPS who could benefit from neoadjuvant chemotherapy.

Diagnostic accuracy of percutaneous biopsy in retroperitoneal sarcoma

Background

Percutaneous biopsy is recommended before surgery for suspected retroperitoneal sarcoma (RPS) to confirm the histological diagnosis and guide surgical strategy. The present study aimed to establish the diagnostic accuracy of percutaneous core biopsy with respect to histological diagnosis and tumour grade.

Methods

Data on patients with suspected RPS who underwent percutaneous biopsy followed by surgical resection between 2005 and 2016 at one of two tertiary European sarcoma units were reviewed. Histological tumour type and tumour grade on biopsy were correlated with postoperative histology to evaluate diagnostic accuracy.

Results

A total of 239 patients underwent percutaneous core biopsy followed by surgical resection in Milan (163, 68·2 per cent) or Birmingham (76, 31·8 per cent). Diagnostic accuracy varied with histological diagnosis (P &lt; 0·001), but demonstrated overall concordance with final pathology following resection in 67·2 per cent of biopsies (κ = 0·606). The majority of discrepancies occurred in dedifferentiated liposarcoma (DDLPS), owing to under-recognition of dedifferentiation in this group. Concordance between pathology on biopsy and resection improved to 81·1 per cent when DDLPS and well differentiated liposarcoma were grouped together as liposarcoma. Grade on biopsy was concordant with grade on resection specimen in 60·4 per cent of tumours (κ = 0·640). Diagnosis of high-grade tumours on biopsy had a high specificity (98 per cent), and moderate positive predictive value (85 per cent) and negative predictive value (78 per cent).

Conclusion

A diagnosis of DDLPS or leiomyosarcoma on percutaneous biopsy is highly reliable. High-grade sarcomas can be identified with high specificity, which opens the door to a study on neoadjuvant therapy in these patients.