Pencil-shaped softening of the spinal cord. Pathologic study in 12 autopsy cases.

This report describes pathologic findings of pencil-shaped softening in 12 autopsy cases. Nine cases were associated with extradural metastasis of malignant tumor and three were observed in brain death. The cavity of the pencil-shaped softening containing necrotic debris and abundant macrophages was located mainly in the ventral part of the posterior column or the dorsal horn. It extended longitudinally over several segments of the cord, predominantly in an upward direction, and had a very clear demarcated margin from the compressed surrounding tissue. Reactive change of the surrounding tissue was very rare. Pencil-shaped softening was found most often in the level of the thoracic cord. The cavity was always continuous with an area of transverse necrosis or and area of patchy necrosis. In previous reports, the factor of circulatory disturbance was considered important for the pathogenesis of pencil-shaped softening. In addition, we believe that mechanical compression is also an important factor.