Discal Cyst Associated with Myxoid Change and Apoptosis of Herniated Disc Materials

Abstract

Discal cyst is a lumbar intraspinal cyst communicating with intervertebral disc, and previously reported series described the wall of these cysts as consisting of dense fibrous connective tissue. We report a 29-year-old Japanese male with discal cyst showing unusual histological features. Clinical symptoms in the current case as well as imaging features including discography were similar to those previously reported. However, the wall of the cyst consisted of disc material with myxoid degeneration. In addition, apoptosis of chondrocytes was diffusely observed in the herniated disc material. The current case was considered a histological variant of discal cyst. Myxoid degeneration of herniated disc material with diffuse apoptotic change of chondrocytes was probably associated with the formation of discal cyst.

Intraspinal cysts with a distinct connection to the corresponding intervertebral disc has been called discal cyst [1]. To clarify the location of this lesion, Coscia and Broshears in 2002 introduced the term “intracanalicular discal cyst” [2]. In the largest series of this condition, Chiba et al. reported that the wall of the discal cyst consisted of dense fibrous connective tissue [1]. We recently encountered a case showing typical clinical and imaging features of discal cyst, but its histological findings differed from those of previous reports. This study describes a case showing unusual histological features of discal cyst, and discusses its pathogenesis. All protocols were accepted by the Institutional Review Board at our institution. Informed consent was obtained from the patient.