Impact of location on resectability and neurological outcome in spinal cutaneous inclusion tumors

Sundus Ali; Fauzia Sajjad; Adnan Qasim; Anwar M Chaudhary; Akmal M Azeemi; Asif Shabbir

doi:10.4103/isj.isj_30_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 6 | Issue : 1 | Page : 89-95

Impact of location on resectability and neurological outcome in spinal cutaneous inclusion tumors

Sundus Ali¹, Fauzia Sajjad², Adnan Qasim³, Anwar M Chaudhary², Akmal M Azeemi², Asif Shabbir²
¹ Department of Neurosurgery, King Edward Medical University, Mayo Hospital, Lahore, Pakistan; Department of Neurosurgery, Punjab Institute of Neurosciences, Lahore General Hospital, Lahore, Pakistan
² Department of Neurosurgery, Punjab Institute of Neurosciences, Lahore General Hospital, Lahore, Pakistan
³ Department of Neurosurgery, King Edward Medical University, Mayo Hospital, Lahore, Pakistan

Date of Submission	12-Apr-2022
Date of Decision	12-Aug-2022
Date of Acceptance	24-Aug-2022
Date of Web Publication	11-Feb-2023

Correspondence Address:
Adnan Qasim
Department of Neurosurgery, King Edward Medical University, Mayo Hospital, Lahore
Pakistan

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/isj.isj_30_22

Abstract

Background: Spinal cutaneous inclusion tumors are extremely rare, accounting for less than 1% of intraspinal tumors. The existing literature is scarce; in last two decades, only eight case series have documented more than 10 patients. We tried to figure out if intramedullary and extramedullary locations have an impact on outcomes in terms of extent of resection and neurological recovery. Materials and Methods: A retrospective review of intraspinal epidermoid and dermoid tumors operated at our Neurosurgical Department, between May 2006 and May 2021, was made. McCormick grading was used to evaluate the neurological status of all patients at presentation, after surgery, and at the follow-up visit in the outpatient clinic. The neurological status at the last follow-up was taken as final. Results: Of 15 cases, eight (53.3%) were males with the age at presentation ranging from 7 to 60 years (mean = 24.4 years). Spinal dysraphism was associated in four patients. The proportion of region involved in descending order was lumbar (46.6%), thoracic/thoracolumbar/lumbosacral (13.3% each) and cervicothoracic/sacrococcygeal (6.6% each) with 11 gross total resections (73.3%) and four subtotal resections (all intramedullary). Two-tailed Fischer’s exact test showed a significant correlation between location, extent of resection, and neurological recovery, whereas histological subtype and region had no significant impact on the outcome. Conclusions: To the best of our knowledge, this is the eighth largest study in the last two decades, reporting 15 cases with long-term follow-up. We attempt to bring clarity to the notion of location having no effect on resectablity by specifying location in terms of spinal compartment involved and describing spinal level as region. Overall, our gross total resection rate was lower (73.3%) than other contemporary studies (86.6%–92%), but a subgroup analysis with regard to the location of tumor revealed the intramedullary location to be the primary determinant of the extent of resection.

Keywords: Dermoid, epidermoid, intramedullary lesion, spinal tumor, surgical resection

How to cite this article:
Ali S, Sajjad F, Qasim A, Chaudhary AM, Azeemi AM, Shabbir A. Impact of location on resectability and neurological outcome in spinal cutaneous inclusion tumors. Indian Spine J 2023;6:89-95

How to cite this URL:
Ali S, Sajjad F, Qasim A, Chaudhary AM, Azeemi AM, Shabbir A. Impact of location on resectability and neurological outcome in spinal cutaneous inclusion tumors. Indian Spine J [serial online] 2023 [cited 2023 Mar 27];6:89-95. Available from: https://www.isjonline.com/text.asp?2023/6/1/89/369572

Introduction

The term “cutaneous inclusion tumors” (CIT) has been coined for more than a decade based on the suggestion that histological subtyping into dermoid and epidermoid does not affect clinical outcome.^[1] These benign, slow-growing tumors are rare, accounting for less than 1% of intraspinal tumors.^[2],[3] Various theories exist regarding the origin of these tumors being congenital or acquired, the former imparting cutaneous element during faulty neural tube closure during the third to eighth week of gestation^[4] and latter focusing on dermal elements being driven inside along the lumbar puncture needle^[5],[6] or during meningomyelocele repair.^[7],[8] A number of associated developmental anomalies signifying faulty neural tube closure such as spina bifida, dermal sinus, and diastematomyelia confirm the congenital origin.^[2]

In contrast to the epidermoid that is lined by stratified squamous epithelium, dermoids have additional elements termed as dermal appendages consisting of sebaceous glands, sweat glands, and hair follicles. Unlike true neoplasms that grow by progressive cell division, these tumors enlarge by the desquamation of epithelial cells and the secretion of dermal elements into the cystic cavity.^[9] The clinical presentation and symptoms depend on the location and extent of the tumor.

The most common location is reported to be intradural extramedullary in the lumbosacral region.^[3],[10] Motor disturbance, pain, sensory disturbance, and urological dysfunction are the most frequently reported symptoms.

Imaging features on magnetic resonance imaging are variable, though typically epidermoids follow cerebrospinal fluid signal, whereas dermoids tend to be more similar to fat, on T1- and T2-weighted sequences, but a considerable overlap exists corresponding to different concentrations of keratin, cholesterol, and water content.^[11],[12] This discrepancy is directly addressed by Van Alast, reporting that radiological diagnosis only correlated with final histopathology in five out of 17 cases.^[1]

The recommended treatment like any other spinal tumor is mainly surgical, but when the tumor adheres tightly to neural structures, a complete removal of the cyst capsule is not recommended.^{[2],[10],[13]} Although intraoperative neurophysiological monitoring (IONM) is increasingly being promoted as a standard of care in spinal surgery, being safe and reliable,^{[10],[13],[14],[15]} no difference in clinical outcomes with or without the use of IONM has been reported.^[16],[17]

The objective of the study was to evaluate the impact of location of spinal CITs on outcome in terms of the extent of resection (EOR) and neurological recovery.

Materials and Methods

All patients who were surgically treated at our neurosurgical department between May 2006 and May 2021, for intraspinal epidermoid and dermoid tumors were included. After approval by the local Institutional Review Board (IRB no. 00-07-21), charts were reviewed to note demographics such as age and gender, presenting symptoms, associated dysraphism and/or other congenital anomalies, location and region involved, magnetic resonance imaging characteristics, and operative findings. McCormick grading was used to evaluate neurological status of all patients at presentation, after surgery, and at follow-up visits in out-patient clinics. The neurological status at the last follow-up is taken as final.

All patients underwent posterior midline multilevel laminectomy followed by microsurgical removal of the tumor. Gross total resection (GTR) was defined as at least 95% removal of the tumor while any resection between 80% and 95% was termed as subtotal resection (STR). Patients were followed to assess neurological status at variable intervals following surgery according to McCormick’s grade. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS version 26) for Windows. Continuous data, i.e., age, were expressed as mean ± standard deviation and categorical data, i.e., gender, location, region, and clinical grade, were expressed as numbers and percentages. Two-tailed Fisher’s exact test was applied to document an association between categorical variables such as EOR, neurological improvement, histological subtype, location of tumor, and region, and P values equal to or less than 0.05 were considered statistically significant.

Surgical technique

Surgical excision was done under routine general anesthesia in the prone position. After laminectomy, dural opening and microsurgical excision of lesion were carried out in all 15 cases.

For the intradural extramedullary tumor, the cord–tumor interface was clear. Smaller lesions were taken as en bloc, whereas larger than 2 cm were internally decompressed first and then removed in total. For the intramedullary tumors, cord–tumor interface was clearly identifiable in all cases, but at some places, capsule was tightly adherent to the cord and/or roots, thus leaving it behind. We do not have IONM available in our set-up; therefore, in intramedullary CIT case, we only took out freely dissectible tumor tissue from the cord and left the rest behind. Care was taken throughout the procedure to avoid spillage of cyst content to prevent the risk of aseptic meningitis. Watertight dural closure was ensured for all cases. Further reinforcement with fibrin glue was done to prevent the risk of dural leak. Primary dural closure was possible in all but two cases of STR, where fascia lata dural patch graft was applied. Despite all maneuvers, two of our cases had postoperative cerebrospinal fluid leak from wound managed conservatively by tension sutures over skin.

Results

Of 15 cases, eight (53.3%) were males with the age at presentation ranging from 7 to 60 years (mean = 24.4 years). Follow-up was 0–4 years (mean = 1.73 years). The most common region involved was lumbar (7/15, 46.6%), followed by thoracic, thoracolumbar, and lumbosacral regions (2/15, 13.3% each). Cervicothoracic and sacrococcygeal were the least encountered ones in our series (1/15, 6.6% each). Regarding location, intradural extramedullary was the most common (9/15, 60%), four cases (26.6%) of intramedullary and two (13.3%) extradural were recorded. Plain x-rays of the vertebral column revealed coexisting spina bifida of variable severity in four patients. One had associated dermal sinus, none with diastematomyelia and lipoma. No patient in our series reported any history of lumbar puncture or trauma to the level involved. The involved masses had up to three segments in 73.3% of patients (11/15), and masses of more than three segments occurred in 26.6% of patients (4/15). Two-tailed Fischer’s exact test showed a significant correlation between the EOR, motor recovery, and location (P value = 0.001 each), whereas histological subtype and region had no significant impact on the outcome (P value = 1.000 and 0.022, respectively). The details are summarized in [Table 1].

Table 1: 14-year experience with cutaneous inclusion tumor development in 15 patients

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Demographics and clinical spectrum

Mean age of presentation in our series is 24.4 ± 13.1 years, which is consistent with the reported mean age in the literature.^[13] Male predominance is noticed in all but one series.^[18] Pain was also the most common symptom in our series, followed equally by lower limb weakness and sphincter disturbance (86.7%). Associated spina bifida was noticed in four patients (26.6%) [Figure 1].

Figure 1: (Case 4) Sagittal magnetic resonance imaging T1, T2, contrast (A, B, C) images, demonstrating an intramedullary dermoid tumor at D12–L2 levels. Red arrow (A, D) points toward the absence of bony elements over the lesion, Yellow arrow (D) depicting the scalloping of posterior vertebral body because of long-standing nature of the lesion. Plain x-ray (E) also shows absent spinous processes, and blue arrow depicts interpedicular widening

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Location vs region

Dermoids have affinity for lumbosacral region [Figure 2] and intradural extramedullary location, whereas epidermoids are found to be uniformly distributed both as per region and location.^[19] We did not find any such association in our series (P value = 0.516) [Table 2] and [Table 3].

Figure 2: (Case 9) Sagittal magnetic resonance imaging (MRI) T2 and contrast (A and B) images demonstrating an intradural tumor at L3–L4 levels. Cord is ending lower than usual and is tethered to the mass marked with *. Axial T2 preoperative (C) showing mass completely occupying the canal and postoperative (D) dural sac with cauda equina roots, orange arrow. Sagittal postoperative MRI contrast and T2 (E and F) showing gross total resection

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Table 2: Analysis based on tumor location and different variables

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Table 3: Analysis based on tumor spinal level and different variables

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Location vs extent of resection

The EOR was found to be significantly influenced by the intramedullary location of the lesion (P value = 0.001). All four intramedullary lesions in our series were rendered to subtotal excision (26.7%), being tightly adherent to the surrounding spinal parenchyma [Figure 3].

Figure 3: (Case 14) Sagittal MRI T1 and T2 images (A and B) demonstrating a mixed intensity intramedullary lesion at D10–L1 level. Hyperintense part (asterisk) on axial section (C) signifies high protein content, while (blue arrow) on axial section (D) depicts cord expansion as a sign of intramedullary lesion, plain x-ray (E) demonstrates a coexisting bony dysraphism from D10 to L1

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On the other hand, extramedullary lesions had a good arachnoid plane facilitating gross total excision in 73.3% cases in our series. The EOR in terms of intramedullary location as reported in the literature is depicted in [Figure 4].

Figure 4: Extent of resection according to the location of cutaneous inclusion tumor, as reported in the literature (Wang et al. and Liu et al. are excluded because of a lack of mention of extent of resection in terms of location)

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Impact of IONM in the extent of resection

In spinal tumor surgery, no difference in clinical outcomes with or without the use of IONM has been reported^[16],[17]; still, the use of IONM is increasingly promoted as a standard of care being able to detect early neurological compromise, thus adding to surgeon confidence and act as safety net for medicolegal issues. We lack the facility of IONM being a resource-limited set-up; therefore, we compared our results with those utilizing IONM. The studies utilizing IONM reports GTR rate range from 86.7% to 92% vs 73.3% in our study without IONM. This, when subjected to subgroup analysis, revealed that the former had only one IM in contrast to four in our series, implying the key role of location impacting EOR.

Clinical outcome

Motor power improved by at least one grade in 11 out of 15 patients (73.3%) in the postoperative period, which is close to that reported in the literature (70.7%).^[15] The rate of improvement in McCormick grade over the study period is displayed in [Figure 5].

Figure 5: The McCormick grade before surgery, after surgery, and at the last follow-up visit

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Discussion

CITs constitute a distinct entity within dysembryogenetic tumors, restricting to dermoid and epidermoid tumors only, unlike the wider spectrum of the later adding lipomas and teratomas. Overall, CITs account for about 14% of all tumors in the central nervous system affecting cranium six times more than spine.^[2] Because of the relative rarity (0.8%–1.4%) of these tumors in spine,^[18] there are only handful of series reporting more than 10 cases, leading to a lack of robust evidence regarding factors affecting outcome. Here, we report a relatively small cohort of 15 patients with an attempt to address the issue and reviewed the literature from the last two decades with special focus on the impact of location on the EOR in spinal CIT. To the best of our knowledge, this is the sixth largest series including both adults and pediatric patients detailing location in terms of intramedullary/extramedullary location. Studies that lack the detail of location were excluded [Table 4].

Table 4: Previously reported case series containing more than 10 reported cases each in past 20 years

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Recurrence

Although the theoretical risk of recurrence is there in cases of STR, actual recurrence is much less reported. Recurrence rate varies in the literature from 11.5% to 21% (Wang 2018).^[13] Our recurrence rate was 6.7%. In attempt to reduce recurrence rate, postoperative radiotherapy and intraoperative chemotherapy have been reported in few cases.^[21] However, the widespread use is limited because of side effects in the short and long term. Also the use of Ommaya reservoir for the suction of intramedullary cyst contents has been reported with some success against recurrence.^[22]

Limitations

Our study has small cohort and retrospective.

Future directions

We recommend meta-analysis and systemic review.

Conclusion

Intramedullary location, regardless of histopathology and region, is the key factor in determining outcome in terms of EOR as well as clinical improvement in spinal CITs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Ethical policy and institutional review board statement

This study is approved from IRB. The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki: http://www.wma.net/en/30publications/10policies/b3/index.html.

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