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We present 4 cases of facet cyst haematoma in the ligamentum flavum of the lumbar spine. All patients presented with a one-to-3-month history of back pain or numbness in the legs, and sudden neurological deterioration. One also developed cauda equina syndrome and another developed radiculopathy. In all cases, magnetic resonance imaging showed a mass with high signal intensity on both T1- and T2-weighted images. Facet arthrography and computed tomography revealed communication between the mass and the neighbouring facet joint. The haematomas were removed en blocwith the ligamentum flavum. They were surrounded by the ligament and contained degenerated and lacerated elastic fibres but no synovial lining cells. Facet cyst haematoma is so-named because of bleeding from tissue adjacent to the facet joint into a pre-existing facet cyst.

We report a case of IgA nephropathy with focal and segmental deposition of type III collagen in mesangium, confirmed by immunohistochemical and electron microscopic methods. Tissue negative staining showed that focal and segmental fibrotic lesions in the mesangial area consisted of disarrayed or curled striated collagen fibers and striated membranous structures. Diabetes mellitus, hypertension, and advanced glomerular sclerosis were absent in this case, and mesangial cells surrounding the type III collagen showed vacuolar degeneration revealed by electron microscopy. Production of type III collagen may be the marker for phenotypic change of mesangial cells in immune-mediated glomerular diseases. (Am J Kidney Dis 1998 Jul;32(1):146-52)