SURGERY

Lumbar Discal Cyst: a Rare Cause of Low Back Pain and Sciaticain a Young Bodybuilder—Case Report

Myoung Soo Kim1& Eun-Jung Jung2

& Eunhee Kim3& Sang-Bong Chung1

Accepted: 22 August 2018 /Published online: 26 September 2018# Springer Nature Switzerland AG 2018

Introduction

A discal cyst is a rare intraspinal, extradural mass with a dis-tinct communication with the corresponding intervertebraldisc [2, 9]. All reported cases demonstrate that the clinicalpicture determined by discal cyst is indistinguishable fromother causes of low back pain and radiculopathy such as con-ventional disc herniations. There is limited information on thepathogenesis, natural course, and surgical treatment. Thus,most neurosurgeons are not aware of this disease entity.

The purposes of this report are to describe a case of discalcyst and to raise awareness of the disease and its radiologicalfindings, to consider it in the differential diagnosis of a phys-ically active young patient presenting with sciatica and lowback pain. Amore accurate knowledge of a disease can lead toavoid unnecessary investigation and delayed treatment.

Case Report

A 17-year-old man had a 1-week history of severe low backpain radiating to hip and left anterior thigh. The pain wasworse when the patient was sitting on a toilet seat and partiallyrelieved when he was lying down for rest. Physical examina-tion revealed full strength in both lower extremities. Therewas no pain during the femoral nerve stretch test. He wasreferred to our hospital with impression of intraspinal tumor.

An MRI scan demonstrated about 2.5-cm ovoid mass le-sion located in the left ventral epidural space at the level of L1/2 intervertebral disc, severely compressing the ventrolateralaspect of the thecal sac. The cystic mass showed homoge-neous iso-intensity to the CSF. The rim of the lesion wasmildly enhanced after administration of gadolinium underT1-weighted MR imaging (Fig. 1). Connection of the cystwith adjacent annulus fibrosus was suspected on T2-weighted axial image. There was no bony erosion of the ad-jacent vertebrae. However, posterior arch in T12 was notcompletely fused, which was demonstrated on computed to-mography (Fig. 1d). We considered discography to obtaininformation of communication between the cystic lesion andthe corresponding disc. But, we could not because of patient’srefusal of the invasive procedure.

After retraction of the thecal sac and left L2 nerve rootfollowed by L1 total laminotomy, a dark blue-colored cystcompressing the thecal sac was visualized over the ventrolat-eral side. The cyst was adhered to the thecal sac. With metic-ulous dissection around cyst, the cyst wall was punctured tominimize the retraction of thecal sac. The cyst contained se-rous fluid without blood. An apparent connection between thecyst and the corresponding intervertebral disc was identifiedthrough the defect in the annulus fibrosus (Fig. 2). There wasno evidence of disc herniation. Pathological examination ofthe cyst wall revealed fibrous connective tissue with hemosid-erin deposits without lining cell layers or disc materials(Fig. 3). It was compatible with discal cyst. The patient’ssymptoms were completely resolved immediately after sur-gery. He was followed up regularly and remained asymptom-atic 1 year later.

Discussion

Lumbar discal cyst, intraspinal extradural cyst that communi-cates with the intervertebral disc, is a relatively new clinicalentity that reported in the Japanese literature in the second half

This article is part of the Topical Collection on Surgery

* Sang-Bong Chungphoenixchung@nmc.or.kr

1 Department of Neurosurgery, National Medical Center, Eulji-ro 245,Jung-gu, Seoul 04564, Republic of Korea

2 Department of Pathology, National Medical Center, Seoul, Republicof Korea

3 Department of Radiology, National Medical Center, Seoul, Republicof Korea

SN Comprehensive Clinical Medicine (2019) 1:4–7https://doi.org/10.1007/s42399-018-0004-9

of the 1990s [2, 6, 14]. It occurs at a slightly younger age andat higher intervertebral levels than typical disc herniation. Itssymptoms are similar with other intraspinal cystic mass le-sions. A variety of cystic lesions may develop within the spi-nal canal including perineural cyst [13, 15], extradural arach-noid cyst [10], and synovial cyst of the facet joint [7], as wellas extruded disc fragment in the epidural space [11]. Locationcan be a helpful discriminating factor, as synovial cysts devel-op from facet joints and are therefore usually located on theposterolateral aspect of the thecal sac. It can contain mucinousfluid or blood, has synovial lining cells in its wall [7], and hasno communication with the intervertebral disc. Perineuralcysts may have the same signal characteristics as non-hemorrhagic discal cysts with a thin wall; however, they aremultiple and in close relationship with the dorsal nerve root[13, 15]. They do not show peripheral enhancement followingcontrast administration. Extradural arachnoid cyst occurs pre-dominantly in younger persons and is located primarily in thethoracic spine usually in the dorsal aspect of the dural sac.Enhancement of an arachnoid cyst is not seen in contrast-enhanced MR images [10]. An extruded disc fragment in theepidural space can occur in the ventrolateral epidural spacejust like a discal cyst. MR image shows a non-enhancing discfragment with surrounding thick granulation tissue [11].

The etiology and pathogenesis of an intraspinal discal cystremain unknown. Two hypotheses for the formation of thesecysts have been suggested [2, 6]. Chiba et al. [2] proposed thatdisc injury in the setting of mild disc degeneration causes anannulus fibrosus fissure in the posterior intervertebral disc, lead-ing to hemorrhage of the epidural hematoma and a blood-filledor hemosiderin-containing cyst. Kono et al. [6] proposed thatdiscal cysts result from focal degeneration and cystic softeningof collagenous connective tissue of the disc with fluid produc-tion, similar to the mechanism of meniscal cyst formation oc-casionally observed in patients with meniscal degeneration inthe knee. The extruded fluid incites an inflammatory responseleading to reactive pseudo-membrane formation and the devel-opment of the discal cyst [6]. We prefer this hypothesis for thepathologic findings of the cyst wall, including fibrous structurewithout synovial lining cells in our case, which is compatiblewith pseudo-membrane. Our patient presented with mild discdegeneration. His career as a bodybuilder implies a prior historyof severe and repetitive mechanical stress, including raisingabdominal pressure like Valsalva maneuver. But in addition todisc stress caused by bodybuilding exercises, it is plausible thatbony anomalies in spine (incompletely closing of posterior archin T12) also may contribute to further disc degeneration, and byextension, to the evolution of the discal cyst.

Fig. 1 Sagittal T2-weighted (a)and axial T2-weighted magneticresonance (MR) image (b)demonstrates a intraspinal,extradural cystic lesion locatingalong the L1–L2 vertebral bodyhaving connection (arrow) withL1–2 intervertebral disc. Post-gadolinium MR image (c)demonstrates mild rimenhancement around the cyst.Incomplete closing of posteriorarch of T12 detected on computedtomographic axial image (d,arrow)

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In most reported cases, the pain and symptoms of patientsafter surgical removal were remarkably relieved [4, 5, 8]. Inour case, the discal cyst was easily resected using a micro-scopic approach. It is difficult to draw evidences on the besttreatment of discal cysts as the natural history and the long-term prognosis remain unclear. Several authors have docu-mented spontaneous resolution of discal cyst under conserva-tive management, but surgery (endoscopic resection orlaminotomy with cyst excision) is the most common treat-ment, especially in physically active patients [3, 8, 12].More cases with longer follow-up are needed to provide ther-apeutic guidelines [1].

It is important to be aware of discal cyst, to recognize itsappearance on MRI, and to be able to differentiate it from thatof the more common cystic lesions within the spinal canal.Once discal cysts are diagnosed via a meticulous review of

MR image, a gross total resection of the cyst can providecomplete relief of the symptoms.

Compliance with Ethical Standards

Conflict of Interest The authors declare that they have no conflict ofinterest.

Consent for Publication The patient has consented to submission of thiscase report to the journal.

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Fig. 2 A dark blue-colored cystic lesion compressing the thecal sac isvisualized over the ventrolateral side under microscopic view (a, blackarrow: thecal sac, white arrow: discal cyst). The communication betweendiscal cyst and corresponding intervertebral disc is identified (b, blackarrow: connection point through fissure in annulus fibrosus, white arrow:collapsed discal cyst)

Fig. 3 Cyst wall composed of fibrous connective tissue without anyepithelial lining. Fibroblastic proliferation and inflammatory cells werenoted around the cyst (a, H&E, × 200). Hemosiderin pigment in the cystwall was observed (b, H&E stain, × 200)

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