The International Society of Urological Pathology Education web—a web-based system for training and testing of pathologists

Abstract

Pathology training resources remain scarce in many parts of the world. With rapid economic development comes the need to educate new pathologists to meet the medical care demands. Our aim was to set up a cost-effective system for training and testing the diagnostic skills of pathologists. Pathologists in nine countries in Asia and South America were invited by the International Society of Urological Pathology (ISUP) to participate in a prostate pathology education course combining image-based tests with lectures and on-line tutorials. The tests and tutorials are available free of charge at the ISUP education website www.edu.isupweb.org. A total of 603 pathologists registered on the website. Of these, 224 completed pre- and post-lecture assessments (tests 1 and 2). Replies were classified as correct/acceptable, when a lesion was accurately classified into clinically relevant categories (benign, cancer, high-grade prostatic intraepithelial neoplasia, intraductal carcinoma of the prostate). The rate of correct/acceptable replies increased from 60.7 to 72.3% in Tests 1 and 2, respectively. In Test 1, pathologists from upper middle, lower middle, and low resource countries gave a correct/acceptable diagnosis in 65.8%, 61.0%, and 47.4%, respectively. Their results improved in Test 2 to 76.4%, 72.5%, and 62.8%, respectively. The greatest improvement in diagnostic ability was achieved in pathologists from the low resource group of countries. The use of web-based testing and training, combined with lectures, is an efficient method for improving diagnostic skills of pathologists in low to middle resource countries.

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A Study of XmAb®22841 Monotherapy & in Combination w/ Pembrolizumab in Subjects w/ Selected Advanced Solid Tumors

Conditions:   Melanoma;   Cervical Carcinoma;   Pancreatic Carcinoma;   Triple Negative Breast Cancer;   Hepatocellular Carcinoma;   Urothelial Carcinoma;   Squamous Cell Carcinoma of the Head and Neck;   Nasopharyngeal Carcinoma;   Renal Cell Carcinoma;   Colorectal Carcinoma;   Endometrial Carcinoma;   Non-small Cell Lung Carcinoma;   Small Cell Lung Carcinoma;   Gastric or Gastroesophageal Junction Adenocarcinoma;   Advanced or Metastatic Solid Tumors
Interventions:   Biological: XmAb®22841;   Biological: Pembrolizumab (Keytruda®)
Sponsors:   Xencor, Inc.;   ICON plc
Not yet recruiting

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Multiparametric Magnetic Resonance Imaging Versus Fine Needle Aspiration Cytology for Parotid Gland Neoplasms

Conditions:   Parotid Neoplasm;   Parotid Cancer
Interventions:   Diagnostic Test: Multiparametric Magnetic Resonance Imaging;   Diagnostic Test: Fine Needle Aspiration Cytology;   Diagnostic Test: Clinical Evaluation;   Diagnostic Test: Final Histopathological Diagnosis
Sponsor:   Davide Di Santo
Recruiting

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Benefits of 1-Year Lifestyle Modification Program on Exercise Capacity and Diastolic Function Among Coronary Artery Disease Men With and Without Type 2 Diabetes

Metabolic Syndrome and Related Disorders, Ahead of Print.


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Pneumocephalus and pneumoventricle

CASE REPORT

Year : 2019  |  Volume : 14  |  Issue : 1  |  Page : 325-328

Delayed pneumoventricle following endonasal cerebrospinal fluid rhinorrhea repair with thecoperitoneal shunt

Shyam Sundar Krishnan, Adarsh Manuel, Madabhushi Chakravarthy Vasudevan
Department of Neurosurgery, Achanta Lakshmipathi Neurosurgical Centre, Voluntary Health Services Hospital, Chennai, Tamil Nadu, India

Date of Web Publication

21-Feb-2019

Correspondence Address:
Dr. Shyam Sundar Krishnan
Department of Neurosurgery, Achantha Lakshmipathy Neurosurgical Centre, Voluntary Health Services, TTTI Post, Taramani, Chennai - 600 113, Tamil Nadu 
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/ajns.AJNS_224_18

Abstract

Pneumocephalus and pneumoventricle are well-documented in neurosurgical practice. Although both are common posttraumatic sequelae, iatrogenic causes are also well recognized. Iatrogenic causes may be seen after intracranial surgical procedures or cerebrospinal fluid (CSF) diversion procedures. Small amount of pneumoventricle postshunt procedure is usually a self-limiting condition. Rarely, the patient may develop tension pneumoventricle which requires emergency intervention. The occurrence of delayed tension pneumoventricle/pneumatocele following surgery for CSF rhinorrhea with CSF diversion procedures is very rare. We report one case of late presentation of delayed tension pneumoventricle with temporal pneumatocele in a patient who underwent transnasal endoscopic repair of CSF fistula followed by thecoperitoneal shunt. This condition is potentially lethal that requires prompt recognition and surgical treatment.

Keywords: Cerebrospinal fluid rhinorrhea, pneumatocele, pneumocephalus, tension pneumoventricle, thecoperitoneal shunt

How to cite this article: Krishnan SS, Manuel A, Vasudevan MC. Delayed pneumoventricle following endonasal cerebrospinal fluid rhinorrhea repair with thecoperitoneal shunt. Asian J Neurosurg 2019;14:325-8

How to cite this URL: Krishnan SS, Manuel A, Vasudevan MC. Delayed pneumoventricle following endonasal cerebrospinal fluid rhinorrhea repair with thecoperitoneal shunt. Asian J Neurosurg [serial online] 2019 [cited 2019 Feb 21];14:325-8. Available from: http://www.asianjns.org/text.asp?2019/14/1/325/250010

Introduction

The occurrence of pneumoventricle as a delayed complication of cerebrospinal fluid (CSF), rhinorrhea repair with thecoperitoneal shunt is a rare presentation. Tension pneumocephalus is a known and common entity as compared to tension pneumoventricle. The presence of pneumatocele in the temporal lobe in association with the above condition makes it a unique clinical presentation.

Case Report

This 48-year-old female presented with complaints of CSF rhinorrhea since 2 months. There was no history or clinical finding suggestive of trauma or meningitis. Her neurological examination otherwise was unremarkable. Computed tomography (CT) face/skull base followed by magnetic resonance imaging (MRI) brain and diagnostic nasal endoscopy were done which showed the defect in the cribriform plate and left a lateral wall of the sphenoid sinus [Figure 1]. Lumbar puncture done showed the CSF opening pressure of 35 cm of water and no evidence of infection.

Figure 1: Magnetic resonance images of the patient showing cerebrospinal fluid fistula in cribriform plate (short arrow) and lateral wall of sphenoid sinus (long arrow) and computed tomography paranasal sinuses bone window showing defect (long arrow) in the sphenoid bone with cerebrospinal fluid filling into the left sphenoid sinus (long arrow) Click here to view

She underwent transnasal endoscopic repair of CSF fistula along with placement of thecoperitoneal shunt with no anti-siphon device. The bath-plug technique was used to seal the defects by introducing a fat plug with a specifically secured vicryl suture into the intradural space, followed by applying traction on the suture to seal the defect much like a bathplug seals a bath. Rectus abdominis fascia graft was harvested from the same abdominal wound used for shunt placement. The defect was further reinforced by fascia, fat and surgical, and fibrin sealant. It was decided to place thecoperitoneal shunt as the CSF opening pressure was very high to prevent the recurrent CSF leak. Postoperatively, she was symptom-free and discharged to home.

After 1 month, she presented with memory disturbances, multiple episodes of vomiting and headache. There was no recurrence of CSF rhinorrhea or postnasal drip. MRI brain showed pneumoventricle with right temporal pneumatocele [Figure 2]. Diagnostic endoscopy was done which showed dislodged fascia graft. She underwent emergency repacking of the CSF fistula with the removal of thecoperitoneal shunt and aspiration of pneumoventricle underwater seal which was under high pressure. Fasica graft was repositioned to cover the defect after sealing it with fat using the bath-plug technique as in the previous surgery. Fat and fascia packing was reinforced with a pedicled Hadad flap and fibrin sealant. She improved in her symptoms postoperatively. Postoperative CT brain showed good resolution of pneumoventricle with reduced size of ventricular system [Figure 3]. She remained symptom free at 6-month follow-up.

Figure 2: Magnetic resonance imaging brain showing pneumatocele (long arrow) in the right temporal lobe and pneumoventricle (short arrow) Click here to view

Figure 3: Postoperative computed tomography brain showing good resolution of tension pneumoventricle and right temporal pneumatocele Click here to view

Discussion

Pneumocephalus is defined as the presence of air in the intracranial compartment due to communication between intracranial and extracranial compartments.^[1],[2],[3] Tension pneumocephalus is a rarer form of pneumocephalus in which the air is under high pressure.^{[1],[2],[4],[5],[6],[7]}Pneumocephalus occur most commonly in head injuries.^[1],[2],[3] Intra- and post-operative pneumocephalus/pneumoventricle is well-documented, especially, in sitting position surgeries, nitrous oxide anesthesia, and CSF diversion surgeries.^[1],[2],[3] Other conditions causing pneumocephalus are CNS infections caused by gas-producing organisms, congenital neurenteric cysts, and postradiotherapy for nasopharyngeal carcinoma.^{[1],[2],[4],[5],[6],[7]} Small amounts of pneumoventricle alone are common after shunt surgeries, ventricular tumor surgeries.^{[1],[2],[3],[8]} Sometimes, wound breakdown following the shunt surgeries may cause influx of air peritubally and cause pneumoventricle.^[9] Delayed tension pneumoventricle is an extremely rare complication and <50 cases have been described in the literature.^[1]Pneumocephalus/pneumoventricle is usually benign which does not require any treatment, and it decreases at a rate of 25% per week.^{[4],[9],[10],[11],[12]}

Two different mechanisms have been proposed in the development of delayed tension pneumoventricle/pneumocephalus.^{[1],[2],[3],[13],[14]}

1. Dandy's theory of ball valve mechanism: one-way ball valve mechanism causing air to flow into the skull through dural defect where the exit is prevented by brain or meninges sealing the leak site
2. Horowitz inverted soda-bottle effect: negative pressure develops inside the cranial cavity as a result of excessive loss of CSF. This drop in intracranial pressure (ICP) causes air to flow from the extra to the intracranial space across the pressure gradient.

In our case, the patient presented with spontaneous CSF rhinorrhea and was treated by endoscopic skull base defect repair with thecoperitoneal shunt placement. CSF rhinorrhea can be due to traumatic or nontraumatic causes. Traumatic can be either due to head injuries causing skull base fractures or due to iatrogenic causes. Spontaneous leaks could be associated with or without raised ICP. High-pressure leaks could account up to 45% of the nontraumatic CSF rhinorrhea.^[15] Sustained increase in ICP causes bony erosion and creation of an osteodural defect in pneumatized parts of the skull base such as cribriform plate, craniopharyngeal canal, sella, and spheno-occipital synchondrosis leading to CSF leak.^[7],[15] CSF leaks in these cases have been postulated to represent a manifestation of benign intracranial hypertension or pseudotumor cerebri.^{[16],[17],[18],[19]} In our case also CSF leak was associated with raised ICP with no evidence of trauma or infection. This could be an underlying benign ICP with or without congenital defect.

Normal pressure leaks represent 55% of the nontraumatic cases of the CSF rhinorrhea.^[20],[21] It is hypothesized that the spontaneous leak is due to point erosions in the skull base which occur in normal person as a result of physiologic alterations in CSF pressure with transient increase in ICP up to 80 mm of water lasting for few seconds.^[15] Other nontraumatic causes of CSF leak include congenital skull base defects, erosion of the skull base by tumors, infection, mucocele, and following radiation.

CSF diversion in patients with long-standing raised ICP may result in the pneumoventricle by air aspiration through a preexisting congenital or iatrogenic skull base erosion/fistula.^[3] These fistulous sites/erosion points are plugged by scarred meninges or gliotic brain which open up due to a drop in ICP causing inward flow of air. This air is prevented from escaping by temporarily resealing of meningeal cicatrix and this cycle repeatedly happens, resulting in tension pneumoventricle (ball valve mechanism). Shunts by their siphon effect can create significant negative ICP drop which ranges from −30 to −155 mm of water, and sometimes as low as −440 mm of water.^[2],[5] Pneumatocele is located close to the site of fistulae and more common in the temporal lobe. In our case also there might have been a sustained negative pressure caused by the thecoperitoneal shunt without anti-siphon device.

Pneumoventricle presents usually with symptoms and signs of raised ICP such as a recurrent headache with vomiting, impairment of consciousness, seizures, memory disturbances, and gait disturbance. Sometimes, patients present with acute or chronic meningitis. Intracranial splashing sounds called "bruit hydroaerique" are characteristic in some patients. Similarly, our patient also presented with memory disturbances and cognitive impairment during the second presentation.

The delay from CSF shunting to the development of pneumocephalus may vary from a week up to 5 years.^[7],[22] The usage of high-pressure shunts and antisiphon devices have been recommended by some authors to prevent this complication.^[1],[2],[23] Our routine policy is to place Chhabra standard adult thecoperitoneal shunt with no anti-siphon device. However, anti-siphon device has advantages of preventing over-drainage of CSF, and the reservoir gives access to check the patency of the shunt system. We have seen an increased risk of shunt obstruction with anti-siphon device. We had 42 cases who underwent Lumbar-peritoneal (LP) shunts without anti-siphon device in the past 5 years and none of them presented with shunt obstruction or shunt-related morbidity other than shunt migration (five patients) and abdominal pseudocyst (two patients). Programmable shunt provides the benefit of adjusting the pressure setting according to the ventricular pressure. We routinely do not use programmable LP shunts as ours is a resource-limited center with most of the patients coming from low-socioeconomic strata.

Prevention of infection, treatment of raised ICP, aspiration of pneumoventricle, closure of fistula, and removal of shunt tube are the keys to successful management of tension pneumoventricle secondary to CSF fistula.^[23] Broad-spectrum antibiotics are used after shunt removal, but its prophylactic usage is debated.^[1],[5],[23] Removal of the shunt tube relieves the sustained negative pressure which may cause recurrent pneumoventricle/pneumocephalus. Postshunt removal a temporary CSF diversion is preferred by some authors, especially, if the infection is doubted clinically or confirmed.^[1],[2],[23]

In our case, as there was dislodgement of fat-fascia graft, repacking was done followed by aspiration of pneumoventricle underwater seal and thecoperitoneal shunt was removed. We feel the tension pneumoventricle caused air to dissect into the right temporal lobe region under pressure forming the temporal pneumatocele. The shunt was removed to alleviate negative pressure gradient as it was nonprogrammable shunt with no anti-siphon device. The patient had complete resolution of symptoms after the procedure. This makes us think that we should probably reconsider the usage of anti-siphon device and also a pedicled flap to repair the skull base defects. A programmable valve may be the best choice in financially affordable patients. In patients with normal/moderately high ICP (25 cm of water), a temporary lumbar drain can be considered for few days until the defects heal thus preventing the recurrent CSF leaks.

Conclusion

Although it is a rare entity, tension pneumoventricle should be considered in patients who have undergone CSF diversion procedures along with anterior skull base repair. Sometimes, it can occur as a delayed complication which may lead to acute neurological deterioration and sudden death. Hence, prompt diagnosis is necessary for timely intervention and prevention.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 

References

1.	Tuǧcu B, Tanriverdi O, Günaldi O, Baydin S, Postalci LS, Akdemir H, et al. Delayed intraventricular tension pneumocephalus due to scalp-ventricle fistula: A very rare complication of shunt surgery. Turk Neurosurg 2009;19:276-80.
2.	Ruge JR, Cerullo LJ, McLone DG. Pneumocephalus in patients with CSF shunts. J Neurosurg 1985;63:532-6.
3.	Horton DD, Pollay M, Reynolds AF Jr. Intraventricular pneumocephalus secondary to subcutaneous emphysema: A case report. Neurosurgery 1984;15:557-8.
4.	Perrin RG, Bernstein M. Tension pneumoventricle after placement of a ventriculoperitoneal shunt: A novel treatment strategy. Case report. J Neurosurg 2005;102:386-8.
5.	Jimenez-Jimenez E, Martí SS, Villas MV. Tension pneumocephalus related to radiotherapy for nasopharyngeal carcinoma. Case Rep Oncol Med 2014;2014:327380.
6.	Aoyama I, Kondo A, Nin K, Shimotake K. Pneumocephalus associated with benign brain tumor: Report of two cases. Surg Neurol 1991;36:32-6.
7.	Kawajiri K, Matsuoka Y, Hayazaki K. Brain tumors complicated by pneumocephalus following cerebrospinal fluid shunting – Two case reports. Neurol Med Chir (Tokyo) 1994;34:10-4.
8.	Gönül E, Izci Y, Sali A, Baysefer A, Timurkaynak E. Subdural and intraventricular traumatic tension pneumocephalus: Case report. Minim Invasive Neurosurg 2000;43:98-101.
9.	Garg N, Devi I, Dua R, Arivazhagan A. Tension pneumoventricle following exposure of shunt chamber. Br J Neurosurg 2008;22:121-2.
10.	Radhziah S, Lee CK, Ng I. Tension pneumoventricle. J Clin Neurosci 2006;13:881-3.
11.	Ruiz-Juretschke F, Mateo-Sierra O, Iza-Vallejo B, Carrillo-Yagüe R. Intraventricular tension pneumocephalus after transsphenoidal surgery: A case report and literature review. Neurocirugia (Astur) 2007;18:134-7.
12.	Satapathy GC, Dash HH. Tension pneumocephalus after neurosurgery in the supine position. Br J Anaesth 2000;84:115-7.
13.	Little JR, MacCarty CS. Tension pneumocephalus after insertion of ventriculoperitoneal shunt for aqueductal stenosis. J Neurosurg 1976;44:383-5.
14.	Rizzoli HV, Hayes GJ, Steelman HF. Rhinorrhea and pneumocephalus; surgical treatment. J Neurosurg 1954;11:277-83.
15.	Yadav YR, Parihar V, Janakiram N, Pande S, Bajaj J, Namdev H, et al. Endoscopic management of cerebrospinal fluid rhinorrhea. Asian J Neurosurg 2016;11:183-93.     [Full text]
16.	Schlosser RJ, Woodworth BA, Wilensky EM, Grady MS, Bolger WE. Spontaneous cerebrospinal fluid leaks: A variant of benign intracranial hypertension. Ann Otol Rhinol Laryngol 2006;115:495-500.
17.	Owler BK, Allan R, Parker G, Besser M. Pseudotumour cerebri, CSF rhinorrhoea and the role of venous sinus stenting in treatment. Br J Neurosurg 2003;17:79-83.
18.	Al-Sebeih K, Karagiozov K, Elbeltagi A, Al-Qattan F. Non-traumatic cerebrospinal fluid rhinorrhea: Diagnosis and management. Ann Saudi Med 2004;24:453-8.
19.	Schlosser RJ, Bolger WE. Spontaneous nasal cerebrospinal fluid leaks and empty sella syndrome: A clinical association. Am J Rhinol 2003;17:91-6.
20.	Lopatin AS, Kapitanov DN, Potapov AA. Endonasal endoscopic repair of spontaneous cerebrospinal fluid leaks. Arch Otolaryngol Head Neck Surg 2003;129:859-63.
21.	Banks CA, Palmer JN, Chiu AG, O'Malley BW Jr., Woodworth BA, Kennedy DW, et al. Endoscopic closure of CSF rhinorrhea: 193 cases over 21 years. Otolaryngol Head Neck Surg 2009;140:826-33.
22.	Davis DH, Laws ER Jr., McDonald TJ, Salassa JR, Phillips LH 2nd. Intraventricular tension pneumocephalus as a complication of paranasal sinus surgery: Case report. Neurosurgery 1981;8:574-6.
23.	Sasani M, Ozer FA, Oktenoglu T, Tokatli I, Sarioglu AC. Delayed and isolated intraventricular tension pneumocephalus after shunting for normal pressure hydrocephalus. Neurol India 2007;55:81-2.   [PUBMED]  [Full text]

Figures

  [Figure 1], [Figure 2], [Figure 3]

Subpial cervical subependymoma

CASE REPORT

Year : 2019  |  Volume : 14  |  Issue : 1  |  Page : 329-331

Subpial cervical subependymoma: Report of an unusual tumor with review of literature

Deepak Khatri, Kamlesh Singh Bhaisora, Jaskaran Singh Gosal, Kuntal Kanti Das, Arun Kumar Srivastava
Department of Neurosurgery, SGPGIMS, Lucknow, Uttar Pradesh, India

Date of Web Publication

21-Feb-2019

Correspondence Address:
Dr. Kamlesh Singh Bhaisora
Department of Neurosurgery, SGPGIMS, Raibareily Road, Lucknow - 226 014, Uttar Pradesh 
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/ajns.AJNS_225_18

Abstract

Subependymoma is rare benign neoplasm (World Health Organization Grade I) usually found in the 4^th ventricle and lateral ventricles. They were first described by Boykin as a separate entity in 1954. Subependymoma constitutes only 1%–2% of spinal ependymal tumors. Majority of the spinal subependymoma is intramedullary, with a rare few reported in the extramedullary plane. Clinicoradiologically, subependymoma often mimic more frequent, aggressive tumors of the spine (astrocytoma and ependymoma) which makes them difficult to differentiate. In fact, the diagnosis of subependymoma comes as a histopathological surprise. Maximal safe resection holds the key to good postoperative outcome with a very limited role of adjuvant therapy. Complete excision of the tumor, though desirable, is not feasible in all cases. Owing to their rarity and lack of characteristic clinicoradiological features, there is limited information currently available regarding their preoperative diagnosis and "optimal" management strategy. In this case report, we are discussing a case of eccentric subpial cervical subependymoma discussing important differentiating radiological features, and surgical nuances with an attempt to define "optimal" management strategy.

Keywords: Bamboo leaf sign, cervical, subependymoma, subpial

How to cite this article: Khatri D, Bhaisora KS, Gosal JS, Das KK, Srivastava AK. Subpial cervical subependymoma: Report of an unusual tumor with review of literature. Asian J Neurosurg 2019;14:329-31

How to cite this URL: Khatri D, Bhaisora KS, Gosal JS, Das KK, Srivastava AK. Subpial cervical subependymoma: Report of an unusual tumor with review of literature. Asian J Neurosurg [serial online] 2019 [cited 2019 Feb 21];14:329-31. Available from: http://www.asianjns.org/text.asp?2019/14/1/329/250011

Introduction

Subependymoma constitutes about 1%–2% of spinal ependymal tumors.^[1],[2] Even though they may occur anywhere along the spinal cord, C1–C2 is the most frequent location (24%).^{[2],[3],[4],[5]}

Subependymoma often mimic aggressive intramedullary tumors on radiology and frequently present with pain, sensory-motor deficits, bowel, and bladder dysfunction like them. Due to their benign biological behavior, complete surgical excision is usually considered curative. Owing to a highly controversial role of adjuvant therapy, no consensus has been reached on "optimal" management of these cases.

We report a case of eccentric subpial subependymoma discussing important differentiating radiological features and surgical nuances with an attempt to define "optimal" management strategy.

Case Report

A 36-year-old male presented with pain and progressive paresthesia in right-sided limbs for 3 years without sphincter dysfunction. Examination revealed spastic weakness (Medical Research Council Grade 4/5) in both upper limbs and right lower limb with modified McCormick Grade 2 disability. He also had 30%–40% sensory loss to touch and pain below C5 with impaired posterior column sensations. Magnetic resonance imaging (MRI) showed a well-defined mass lesion extending from cervicomedullary junction to C5, causing expansion of the cord without syrinx formation or tumor cysts. Tumor was eccentrically placed, anterolaterally on right side pushing the spinal cord toward left. It was T1 hypo to isointense, T2 hyperintense without significant contrast enhancement [Figure 1]. Common intramedullary lesions such as astrocytoma and ependymoma were considered among the differential diagnoses.

Figure 1: The typical radiological findings in spinal subependymoma. A well-defined eccentrically placed, intramedullary lesion can be seen extending from cervicomedullary junction to C5 causing distinctive steep dilation of spinal cord: Bamboo leaf sign. Lesion is iso to hypointense on T1-weighted images (a and b) and hyperintense on T2-weighted image. There is no evidence of perilesional edema or syrinx formation (c). No significant enhancement is seen on T1-weighted postcontrast image (d and e) Click here to view

C1–C5 laminectomy for tumor excision was done. Intraoperatively, tumor was greyish, soft, moderately vascular lesion extending along subpial plane on the right side, without distinct planes at either end. Upper half of the tumor was found anterolateral to the cord on right side, and lower part was seen extending ventral to the cord. No myelotomy was required for tumor excision.

Histopathologically, tumor cells with mildly enlarged anisomorphic nuclei were seen clustered in the acellular fibrillary matrix. Mitotic activity and necrosis were absent. These features were consistent with subependymoma. Immunohistochemistry showed weak tumor cell positivity for glial fibrillary acidic protein (GFAP) and S-100, and negative for neuron-specific enolase and epithelial membrane antigen (EMA) with low Ki-67 index (1%) [Figure 2].

Figure 2: (a) Microphotograph showing tumor composed of loose aggregates of cells with intervening hypocellular fibrillary matrix (H and E, ×10), (b) Immunohistochemistry showing expression of glial fibrillary acidic protein (IHC, ×20), (c) Immunohistochemistry shows expression of S-100 (IHC, ×20), and (d) Ki-67 proliferation index showing nuclear positivity in <1% cells (IHC, ×20) Click here to view

Postoperatively, motor power in all four limbs worsened by one grade compared to the baseline. We planned for radiological follow-up without any adjuvant therapy. At 2-month follow-up, motor power and spasticity improved with functional recovery.

Discussion

Nearly 50% of subependymoma are identified incidentally. On the other hand, symptomatic cases occur frequently in 5^th–6^th decade and rarely affect children.^[6],[7],[8] Symptoms may exist months to several years before diagnosis are made, reflecting their indolent behavior. However, they may mimic more aggressive intramedullary tumors clinically. Pain and sensory deficits are the most common initial presentation with the risk of compressive myelopathy and loss of sphincter control later. Therefore, early surgery may preclude a significant morbidity.

Histopathogenesis of subependymoma still remains elusive, with few authors even reporting them as a variant of ependymoma based on electron microscopic study.^[9] Whereas, others believe them to be a separate entity arising from various cells such as subependymal glial cells, subependymal cell plate or as a result of some developmental defect.^{[10],[11],[12]} Krishnan et al. proposed their origin from subpial white matter progenitor cells, which later descend to eccentric, subpial location.^[3]

In contrast with ependymoma, features such as mitotic activity, ependymal rosettes, or perivascular pseudorosettes are rarely found. They exhibit the GFAP and S-100 positivity similar to astrocytic tumors but may show dot-like pattern for EMA due to poor formation of ependymal-type rosettes.^[6] Mitotic index is frequently low (<1%).

Radiologically, it is difficult to establish a definitive diagnosis due to lack of characteristic findings and a limited number of reported cases. On MRI, our case showed an eccentrically placed tumor causing distinctive steep dilation of the cervical cord. It was T1 isointense, T2 hyperintense, nonenhancing lesion without peritumoral edema. Such dilation occurs as a result of tumor growth in the subpial plane and has been termed "Bamboo leaf sign." It may help to differentiate them from ependymoma or astrocytoma which cause gradual fusiform enlargement of the cord.^[13] Therefore, a high index of suspicion for "subependymoma" should be considered in "ependymoma" which have little or no edema with minimal or no contrast enhancement. However, tumor cysts and syringomyelia are very rarely associated with them.

A gross total resection is considered curative without requiring adjuvant therapy. Intraoperative features such as lobulated shape, minimal vascularity, eccentric subpial location, and distinct anatomical planes from normal cord facilitate the dissection. Sometimes, total excision may still be difficult to achieve due to local infiltration leading to neurological deficits. Therefore, it becomes highly pertinent to define an "optimal" treatment in managing them.

In our case, we were unable to achieve total excision for the following two reasons. First, there was loss of plane between tumor and cord parenchyma at cervicomedullary junction. Second, tumor was extending ventral to the cord at its lower end with the high risk of cord traction on attempting its removal. A minimal part of tumor was left behind at these locations to prevent worsening or development of new deficits. Therefore, such a safe surgical approach may be considered "optimal."

Transient weakness in immediate postoperative period similar to our case has been reported earlier in nearly 60% of patients despite a "safe" surgical course; nonetheless, most (76%) of them improve with time.^[14] A study also suggests high incidence of poor outcome owing to the cervicothoracic location of tumor, poor intramedullary microcirculation, and postoperative kyphotic deformity.^[15]

Surgical excision forms the cornerstone of management in cervical subependymoma and also preferred by most surgeons over irradiation in case of recurrence/regrowth of tumor. Currently, the role of adjuvant radiotherapy remains controversial. Although more experience and studies with longer follow-up would be required to gain further evidence.

Conclusion

Cervical subependymoma is an uncommon, benign tumor which lacks characteristic clinicoradiological findings, and often mimic, frequently occurring aggressive tumors. Complete tumor excision, though desirable, is not feasible always. Maximal safe resection holds the key to good postoperative outcome with the limited role of adjuvant therapy.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 

References

1.	Boström A, von Lehe M, Hartmann W, Pietsch T, Feuss M, Boström JP, et al. Surgery for spinal cord ependymomas: Outcome and prognostic factors. Neurosurgery 2011;68:302-8.
2.	Wu L, Yang T, Deng X, Yang C, Zhao L, Fang J, et al. Surgical outcomes in spinal cord subependymomas: An institutional experience. J Neurooncol 2014;116:99-106.
3.	Krishnan SS, Panigrahi M, Pendyala S, Rao SI, Varma DR. Cervical subependymoma: A rare case report with possible histogenesis. J Neurosci Rural Pract 2012;3:366-9.   [PUBMED]  [Full text]
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Figures

  [Figure 1], [Figure 2]