Accuracy of biopsy techniques for limb and limb girdle soft tissue tumors

The biopsy method of choice for soft tissue sarcomas (STS) of the limb and limb girdle is controversial. There have been no randomized controlled trials that compare incision biopsy with Tru-cut biopsy. We present a large series, which includes an analysis of the effectiveness of Tru-cut core biopsy both in a tertiary referral center as well as from many referring hospitals. This is compared with the other methods of biopsy of all soft tissue tumors (STT) referred to this institution.

A retrospective review of all patients who were referred to Royal Marsden Hospital NHS Trust (RMH) from 1989 to 1998.

There were 570 patients (576 lesions) identified. Overall Tru-cut biopsy differentiated benign from malignant tumors with a sensitivity of 99.4%, specificity 98.7%, positive predictive value 99.4%, and negative predictive value 98.7% with similar results for RMH and referral hospitals. Tru-cut identified both tumor subtype and grade in approximately 80% of STS. Incision biopsy had similar sensitivity and specificity for differentiating benign from malignant STT as well as subtype of STS but was less accurate for grade assessment. Tumors from patients who were referred after enucleation had a median maximum tumor diameter (MTD) of 4.9 cm, whereas median MTD of tumors diagnosed at referring hospitals by Tru-cut biopsy was 10.6 cm. (P < 0.001).

Tru-cut biopsy is highly sensitive and specific in the diagnosis of STT as well as subtyping and grading of STS. It is equally effective as incision biopsy in all these parameters and has a lesser morbidity. The failure to use Tru-cut biopsy is most likely because of the possibility that STS is not suspected in patients with small tumors even when they are deep to the investing fascia.