Pigmented villonodular synovitis originating from the lumbar facet joint: a case report

Abstract

The authors successfully treated a rare case of pigmented villonodular synovitis (PVNS) that originated from the lumbar facet joint (L4-5). A 43-year-old man presented with a complaint of left severe sciatica causing difficulty in walking. Magnetic resonance imaging (MRI) demonstrated an extradural mass on the left side at L4 and the mass compressed the dural tube and was continuous with the left L4-5 facet joint. A computed tomography myelogram revealed an extradural defect of contrast medium at the L4 level and an erosion of the L4 lamina. A total synovectomy with unilateral osteoplastic laminectomy was performed. The histological findings were a diagnosis of PVNS. The patient's symptoms resolved completely and the MRI at postoperative 3 years demonstrated no recurrence of PVNS. It is important to totally remove the synovium, which is the origin of PVNS in order to prevent the recurrence. We think that our procedure is reasonable and adequate for lumbar PVNS.

Fig. 1

Sagittal MRI showed the compression of the dural tube due to an extradural mass at the L4 level. Left The mass lesion showed mixed high and iso-intensity on T1-weighted imaging. Right The mass lesion showed mixed high and low intensity on T2-weighted imaging

Fig. 2

The mass compressed the dural tube and was continuous with the left L4-5 facet joint. Left The mass displayed rim enhancement with Gd on T1-weighted imaging. Right The mass lesion invaded the lamina

Fig. 3

The intraoperative photos. Upper left Removing the lamina en bloc temporally, the hemorrhagic tumor mass (black arrows) originated from the left L4-5 facet joint and was observed in the dorsum of the ligamentum flavum. The mass was softly elastic and dark reddish-brown in color; it adhered to the L4 and L5 roots on the left side. Upper right After removing the mass and completing the total synovectomy, the dural tube, L4 root and L5 root were completely decompressed. Lower left The mass (black arrows) adhered to the L4 lamina and was accompanied by bone erosion. Lower right We replaced the laminae to an original position after having removed the tumor. (SP spinous process, D dural tube, P pedicle, SF superior facet, IF inferior facet, and asterisk root)

Fig. 4

Photomicrograph from a histologic section of the resected mass showing mononuclear round cells, foamy cells and hemosiderin-laden macrophages. (H&E, original magnification ×20 and ×4)

Fig. 5

Radiographs obtained 3 years after surgery showed the union of L4 laminae

Fig. 6

T1-weighted imaging with Gd of MRI at 3 years after surgery demonstrated no recurrence of PVNS