Recurrent and non-recurrent pigmented villonodular synovitis: A comparison of clinical and pathologic findings including DNA ploidy and proliferation by digital image analysis

Pigmented villonodular synovitis (PVNS) is a benign intra-articular lesion. Patients are at risk for local recurrence. Factors that predict recurrence are not established. Two groups of patients were retrieved from our files. One consisted of 25 patients who had one or more recurrences within 5 years after primary surgery. The second group contained 18 historical controls free of recurrence for at least 5 years ofter primary surgery. Patient medical records and surgical notes were reviewed. We compared proliferative activity and DNA ploidy using digital image analysis, and other clinicopathologic features between the 2 groups of patients. The location of PVNS was significantly different between the two groups (p = 0.03). In the recurrence group, there were 7 (28 %) cases with disease in the knee. However, none of the controls had disease in the knee. Among recurrent cases, tumors in the knee were, on average, larger than tumors in the small joints. The size of all recurrent tumors was not significantly different than non-recurrent tumors (median of 1.8 cm versus 1.3 cm, respectively; p = 0.06). There were no significant differences in age, sex, completeness of surgical removal, MIB-1 index, DNA ploidy, or the percent of tumor nuclei in the diploid, S-phase, tetraploid, or hypertetraploid DNA histogram categories between the two groups. Our results indicate that recurrent PVNS tumors were more likely to be located in the knee, which may be related to larger tumor size. Patient age, sex, completeness of surgical removal, DNA ploidy, and MIB-1 proliferation were not significantly different between recurrent and non-recurrent lesions.