Poor correlation between biopsy and final diagnosis fon chondrosarcoma

By Elaine Fiedler

Chondrosarcoma is the second most common primary sarcoma of bone. Because treatment is generally based on the histological grade of the tumor, accurate preoperative diagnosis is essential. In their study comparing biopsy diagnosis with the final resection diagnosis, the authors of Podium Presentaton 031 found that biopsy diagnoses of chondrosarcoma are frequently misleading, resulting in inappropriate treatment.

Their study involved 180 patients who were treated for a histological diagnosis of chondrosarcoma of the long bones, pelvis or scapula. The researchers evaluated biopsy-obtained tissue diagnoses and excised specimen diagnoses for 1) identification of cartilage, 2) high versus low-grade match and 3) exact pathologic grade match. They also analyzed subgroups including anatomic site, needle versus open biopsy, and biopsy inside or outside a cancer referral center.

The biopsy diagnosis matched the exact grade of the resection diagnosis in only about one-third of the cases (29.3 percent of pelvic cases; 38.5 percent of long bone cases, and 35.7 percent of scapula cases). There was a higher rate of agreement (approximately 60 percent) between biopsy and resection specimen diagnoses on high- versus low-grade designations. The highest rate of agreement (94 percent) was in the identification of a cartilagnious tumor. Open biopsy was significantly better than needle biopsy (p<.05) in determining high- versus low-grade tumors. No other significant difference existed between subgroups.

The authors expressed the greatest concern about biopsies that undergraded the tumor. Nearly one-fourth of the biopsies diagnosed as low-grade tumors diagnosis had a final diagnosis of a high-grade tumor. Seven (4 percent of total) of the under-graded biopsies resulted in inadequate treatment, which resulted in local recurrence requiring additional procedures.

The authors concluded that “the biopsy alone cannot be relied on to accurately determine the exact histological grade or determine low- or high-grade…Relying on biopsy only could potentially lead to inadequate treatment of patients.” They reported that the greatest utility of the biopsy is to confirm the existence of a cartilage tumor. Treating physicians should use biopsy information in the context of the radiograph and clinical evaluation to guide appropriate treatment.

The authors included Matthew J. Seidel, MD; Patrick P. Lin, MD; Valerae O. Lewis, MD; Christopher P. Cannon, MD; and Alan W. Yasko, MD, MBA, all of Houston, Texas.

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