Abstract

Background: Teratomas are a unique family of tumors derived from two or more of the three embryonic layers: endoderm, mesoderm, and ectoderm. Mature teratomas are comprised the most well-differentiated tissue types and may contain skin, hair, teeth, smooth muscle, respiratory tissues, etc. Infrequently, mature teratomas may be found within the central nervous system and, in exceedingly rare cases, may be occur within the spinal cord itself (i.e., intramedullary/intradural).

Case Description: A 78-year-old female presented with a subacute progressive lower extremity paraparesis. The MR revealed a cystic 81 × 30 × 25 mm intradural/intramedullary spinal mass involving the distal conus with exophytic extension into the L1-L4 spinal canal. Following surgical intervention consisting of a L1-L4 laminectomy, the lesion was largely removed. Pathology of the mass confirmed a large mature teratoma containing a multilobulated cyst that intraoperatively compressed the conus and cauda equina. Immediately postoperatively, the patient significantly improved neurologically. However, on postoperative day 2, she acutely developed a change in mental status with the left gaze preference and hemiparesis. CT brain in the acute setting showed no evidence of causative pathology and subsequent MR brain was unremarkable. The patient’s neurologic deficits progressively improved leading to eventual discharge.

Conclusion: Intrathecal intramedullary/extramedullary mature teratomas of the conus that results in subacute cauda equina syndromes are rare. The differential diagnosis for such lesions exophytic to the conus must include mature teratomas which, though rare, may be readily resected resulting in generally favorable outcomes.

Keywords: Mature teratoma, Neurosurgery, Spinal teratoma

INTRODUCTION

Mature teratomas are one of the three WHO defined variations of teratoma; mature, immature, and teratoma with malignant transformation. Each is derived from two or more of the three embryonic layers: the endoderm, mesoderm, and ectoderm.[ 4 ] Mature teratomas are the most well-differentiated variation, typically showing varying histologic morphologies (i.e., skin, hair, teeth, nerve, brain, smooth muscle, adipose tissue, cartilage, and enteric- or respiratory-type tissue).[ 3 ] Further, they may demonstrate multicystic components that may be watery, mucoid, and/or sebaceous in consistency.[ 2 ]

Mature teratomas, though variable in presentation, are classically found in young females. Only very rarely (0.2%) do they arise within the spinal cord (i.e., intradural/intramedullary/ extramedullary) at the cervical, thoracic, and lumbar levels.[ 3 , 9 , 10 ] Here, we encountered a 78-year-old female with a subacute presentation of paraparesis attributed to an MR-documented intramedullary conus lesion with exophytic extension into the L1-L4 conus/cauda equina. Following excision of the teratoma, the patient largely regained normal neurological function.

CASE DESCRIPTION

A 78-year-old female with a history of a “spinal mass” first documented in 2014, presented with the subacute onset (i.e., over several weeks) of a bilateral paraparesis right greater than left [ Table 1 ].

Table 1:

Compilation of the relevant pre- and post-operative data for this case.

The lumbar MRI revealed an 81 × 30 × 25 mm intrathecal intramedullary conus mass with extramedullary extension into the lumbar canal at L1-L4. The mass was accompanied by multiple complex cysts [ Figures 1a and b ].

Figure 1:

(a) Preoperative T2-weighted image of the cystic mass. The mass appears heterogeneous, ranging from L1 to L4, with an evidence of expansion of the spinal canal and deviation of the conus medullaris and proximal nerve roots in the cauda equina anteriorly. (b) Preoperative T1-weighted image of the cystic mass. There is minimal evidence of T1 hyperintensity within the mass.

Surgery

The patient underwent an urgent L1-L4 laminectomy with removal of the conus-cauda equina multicystic tumor.[ 4 ] (i.e., a large and multilobulated cystic lesion compressing the neural elements). Fenestration of a cystic lobule resulted in extrusion of a nonpurulent milky fluid that proved to be sterile. The cyst was safely dissected off the conus and filum terminale with the use of intraoperative neuromonitoring. Interestingly, there was no gross evidence of accompanying teeth, hair, or visible adipose tissue. There were no intraoperative complications.

Postoperative course and imaging

Immediately postoperatively, the patient was neurologically intact. However, on postoperative day 2, she experienced an acute change in neurologic status of unknown etiology (i.e., severe disorientation, persistent gaze preference with facial droop, and left-sided hemiparesis). CT brain was immediately conducted following the acute decline and showed no evidence of a potentially causal pathology. Subsequently, MR brain and EEG were performed to definitively rule out a new stroke or lesion and seizure activity, respectively. Both were unremarkable. The patient was eventually discharged fully orientated and with progressively improving lower extremity strength. Imaging obtained on postoperative day 0 showed successful resection of the mass without evidence of acute complication [ Figure 2 ].

Figure 2:

Postoperative T2-weighted imaging.

Histology of mature teratoma

Microscopically, the tumor was composed of both solid and cystic components (i.e., that contained blood/debris and showed predominantly pseudostratified ciliated and nonciliated columnar epithelial lining with focal stratified squamous epithelium [endoderm]). The surrounding fibrous connective tissue contained lobules of mature adipose tissue (mesoderm), mature hyaline cartilage (mesoderm), peripheral nerve bundles (ectoderm), Pacinian corpuscles (ectoderm), and focal smooth muscle bundles (mesoderm) [ Figures 3 and 4 ]. No immature structures were seen.

Figure 3:

(a) Solid cystic lesion containing adipocytes, blood vessels, smooth muscle fibers, and pseudostratified columnar epithelium-lined spaces. HE original magnification ×20; (b) Pacinian corpuscles (HE, ×400); (c) ganglion cells and adipose (HE, ×400); and (d) small tubules, vessel, and peripheral nerve bundles (HE, ×400).

Figure 4:

(a) Mature cartilage and loose connective tissue underlying ciliated columnar epithelium resembling bronchial tissue. HE original magnification ×100; (b) ciliated columnar epithelium (HE, ×200); and (c) stratified squamous epithelium (HE, ×200).

DISCUSSION

Classification of teratomas

Historically, cystic intraspinal lesions including teratomatous cysts, neurenteric cysts, and teratoid cysts have demonstrated varying morphologic criteria.[ 6 ] Here, a definitive diagnosis of a mature cystic teratoma was established in accordance with the current WHO classification guidelines (i.e., tissues originating from all three embryonic cell layers were clearly demonstrated within the presence of only highly differentiated cells).[ 4 ]

CT/MR diagnoses for intramedullary/extramedullary conus/cauda equina mature teratoma

The differential diagnosis for an intradural intramedullary/ extramedullary/exophytic conus-cauda equina spinal mass includes myxopapillary ependymoma, paraganglioma, nerve sheath tumor, meningioma, and rarely spinal teratomas.[ 5 ] For mature spinal teratomas, CT scans may confirm the “sack-of-marbles” appearance due to fat globules within the cystic portion of the mass (93% of cases) and calcification due to the presence of teeth (53% of cases).[ 8 ] CT may also demonstrate an intracystic mass adherent to the wall of the teratoma, known as a Rokitansky nodule (hair). On T1-weighted MR images, these lesions may be hyperintense due to their intrinsic fat and high fluid content.[ 8 ] Although imaging findings are often highly suggestive of mature teratomas, definitive diagnosis requires surgical resection and histologic examination of the tissue/mass.

Pathogenesis of mature spinal teratomas

The pathogenesis of spinal teratoma still remains unclear; however, theories include (1) tumors arising from misplaced primordial germ cells from the yolk sac, (2) tumors arising from pluripotent cell rest at sites of neural closure, and (3) malformations giving rise to a dysembrogenic process. Mature teratoma has also been associated with spinal dysraphism, lumbar puncture, and prior spinal surgery.[ 6 , 9 ] Notably, mature teratomas within the spinal cord are slow growing, with an average growth of 1.8 mm/year.[ 8 ]

Mature teratomas: Risk of malignant transformation

Mature teratomas have a 2% risk of malignant transformation and a <1% risk of cyst rupture.[ 7 , 8 ] Thus, diagnosis of a mature teratoma on MR/CT imaging warrants timely surgical intervention regardless of neurological deficits to avoid these potentially severe sequelae.

Efficacy of surgical resection of mature teratomas

As in this case, surgical removal of mature teratomas typically results in significant neurological improvement.[ 1 ] As early diagnosis and gross total resection are correlated with the best surgical outcomes, early diagnostic evaluation and treatment are warranted.

CONCLUSION

Intrathecal intramedullary/extramedullary mature teratomas of the conus that results in subacute cauda equina syndromes are rare. The differentiate diagnosis of such lesions is exceptionally broad, but with rapid identification, these mature teratomas may be readily and completely resected. As was seen here, these patients may, more often than not, go on to extremely favorable neurologic recovery.

Declaration of patient consent

Patient’s consent not required as patients identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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