Review Question - QID 213924

The patient has clinical and MRI findings consistent with localized pigmented villonodular synovitis (LPVNS) given the well-circumscribed soft tissue mass noted in the anterior knee. The treatment for this is an arthroscopic excision of the lesion with a partial synovectomy.

PVNS can be differentiated to both local (LPVNS) and diffuse (DPVNS) depending on the extent of involvement. Overall, there is little role in conservative management for patients with symptomatic PVNS. Management of LPVNS comprises of arthroscopic resection of the lesion as well as partial synovectomy around the location of the lesion. The recurrence rate of arthroscopic resection of LPVNS is considered to be 8%. For DPVNS, treatment is comprised of anterior arthroscopic synovectomy combined with a posterior open approach to remove the posterior synovium as well as areas not able to be removed via arthroscopy (complete synovectomy). The recurrence rate of DPVNS following total synovectomy is reported to be 30% and as such, post-operative radiation is considered in recalcitrant cases to minimize the risk of recurrence.

Li et al. presented a case report of 2 elite female athletes who presented with similar chronic anterior knee pain and tenderness. Both underwent diagnostic arthroscopy with one having excess scar tissue and the other having PVNS. The authors stress that in the cases of equivocal MRI findings and persistent anterior knee pain, a subset of patients may benefit from a diagnostic arthroscopy for an accurate diagnosis.

Simonetta et al. discussed the similarities and differences between LPVNS and DPVNS. They cited the knee as the most commonly involved anatomic location, followed by the hip, ankle, shoulder, and elbow. They went on to present a case of an intra-articular LPVNS with an extra-articular extension through the posterior capsule that was successfully removed in an all-arthroscopic fashion.

De Ponti et al. performed a retrospective case analysis of 19 patients who underwent arthroscopic treatment of PVNS in the knee, with 4 having LPVNS and 15 having DPVNS. The patient's with LPVNS underwent partial synovectomy with excision of the pathologic tissue while the patients with DPVNS were split between extended arthroscopic synovectomy (7 patients) and partial synovectomy (8 patients). The authors noted that in the LPVNS group, arthroscopic local excision resulted in complete and persistent regression of the pathology while in the DPVNS group, patients with a partial synovectomy had a recurrence. They concluded that arthroscopic synovectomy is an appropriate treatment for LPVNS, an extended complete synovectomy must be performed in all cases of diffuse PVNS.

Figure A, B and C are the sagittal T1, sagittal T2 and axial T2 MRI sequences of a knee which reveals a well-circumscribed focal anterior lesion extending into the Hoffa's pad consistent with LPVNS. Illustration A shows the lesion in Figure B outlined.

Incorrect Answers:
Answer 1: Radiation can be effective when COMBINED with lesion removal and synovectomy to minimize recurrence rates. Isolated radiotherapy does not have similar success or a role in treating PVNS.
Answer 3: Given the success that can be achieved with arthroscopic excision, an exclusive open excision would not be recommended for LPVNS or DPVNS
Answer 4: Arthroscopic synovectomy combined with posterior open synovectomy would be the treatment of choice for DPVNS
Answer 5: Given the MRI findings of a well-circumscribed mass, it is appropriate to proceed with an excisional biopsy with complete removal of the lesion, rather than FNA.