The pathological and immunohistochemical analysis of ganglion cyst with hemorrhage in the lumbar ligamentum flavum

Abstract

Object: The ligamentum flavum associated with hemorrhage was studied pathologically and immunohistochemically with special reference to subacute inflammation in order to reveal the mechanisms behind ligament degeneration. Materials and Methods: A 68-year-old man had suffered from pain in the right buttock and thigh for 4 months. L4-5 ganglion cyst compressing the L5 nerve root was revealed by MRI and microscopic ligamentectomy was performed. The specimen was pathologically stained with HE, EVG, AZAN, Congo red and immunohistochemically examined with CD31, CD34, VEGFR2, and vWF. The relationship between micro angiogenesis and grade of degeneration and inflamation in the ligaments was studied. Results: The ganglion cyst, originating from the facet joint, was associated with hemorrhage and inflammation and neovascularization were found around the ganglion. The angiogenesis was distributed from the inflammation area towards the ventral side membrane of the interlaminar ligament. The angiogenesis was observed in a far site from the inflammation and the CD34 positive stromal cells increased as the distance from the ganglion cyst increased. Discussion: The ganglion cyst induced inflammation and angiogenesis. We suspect that these new vessels were stretched and injured with the elastic ligament movement. And this mechanical stressed new vasculature origin bleeding formed the hematoma. Our findings suggest that the CD34 positive stromal cells have potential to respond to the angiogenesis. Conclusion: In our specimen, the inflammation-induced angiogenesis was suspected to cause the bleeding in the ganglion cyst.