Symptomatic postoperative cyst following glioma excision in a pediatric patient: a case report

Abstract

Introduction and importance:

Postoperative cyst formation is a rare but significant complication following central nervous system (CNS) tumor resection. This case report describes a 14-year-old girl who developed a postoperative cyst after glioma excision, successfully managed through a minimally invasive approach.

Case presentation:

A 14-year-old female presented with headache and seizures. Magnetic Resonance Imaging (MRI) revealed a mass in the trigonal region. She underwent surgical resection of the tumor. On postoperative day 7, she developed a symptomatic cyst at the tumor bed. The cyst was drained, resulting in symptomatic improvement. Follow-up assessments confirmed her clinical recovery.

Clinical discussion:

In pediatric patients, postoperative cyst formation is less frequently reported compared to adults. This highlights the need for further investigation into its underlying mechanisms and optimal treatment strategies in children.

Conclusion:

Minimally invasive percutaneous drainage followed by shunting successfully managed the postoperative cyst and prevented recurrence in this pediatric glioma case. Given the absence of standardized treatment protocols, individualized care is essential to ensure the best possible outcomes.

Introduction

Postoperative cyst formation is a rare but serious complication following central nervous system (CNS) tumor excision. The reported incidence varies between 0.4% and 48%, with pediatric cases less frequently documented^[1]. These cysts are attributed to blood-brain barrier disruption, hemorrhage, reactive gliosis, or fluid secretion by residual tumor cells^[2]. In pediatric patients, the risk of cyst formation post-resection is less well-documented compared to adults, necessitating further investigation into its pathophysiology and optimal management strategies.

This report presents a case of postoperative cyst formation in a 14-year-old girl following glioma resection, managed successfully with minimally invasive techniques. This case is important for clinical practice because it highlights the need for early recognition and individualized management of a rare postoperative complication in the pediatric population, for which literature is scarce.

HIGHLIGHTS

• Prompt identification and minimally invasive treatment of postoperative cysts following CNS tumor resection are essential to minimize morbidity and optimize outcomes.

• Postoperative cyst formation, though uncommon, demands early recognition and appropriate intervention.

• Early postoperative imaging is critical to differentiate between cyst formation, hemorrhage, and other complications.

• Individualized patient management is necessary due to the absence of standardized treatment guidelines.

Case presentation

Patient history and symptoms

A 14-year-old female presented with bifrontal headache, vomiting, and generalized tonic-clonic seizures for 2 months. Fundus examination showed no papilledema. Neurological evaluation revealed normal motor strength, tone, and reflexes. There were no signs of neurocutaneous syndromes.

Clinical and diagnostic workup

Magnetic resonance imaging (MRI) revealed a 7 × 5 cm T2-weighted hyperintense, non-enhancing lesion in the left trigonal region (Fig. 1). Differential diagnoses included glioma, metastatic lesion, and low-grade astrocytoma. Routine laboratory tests, including complete blood count, serum electrolytes, CRP, liver and renal function, and metabolic screening, were within normal limits. Lumbar puncture was not performed due to clinical suspicion of raised intracranial pressure.

Figure 1.

Preoperative MRI of the brain displaying a T2 hyperintense, non-enhancing lesion in the left parietal and trigonal region. The FLAIR axial image (A) highlights the extent of perilesional edema, while the T1-weighted post-gadolinium axial image (B) shows no contrast enhancement, suggesting a low vascular component, consistent with a glioma.

Surgical management and immediate outcome

The patient underwent left parietal craniotomy. The lesion was soft in consistency, moderately vascular, with thrombosed vessels, and completely excised under neuronavigation guidance. There was no breach of the ventricle. Immediate postoperative CT (Fig. 2) showed complete excision of the lesion with no evidence of hemorrhage or cyst formation. Histopathological examination revealed a diffusely infiltrating astrocytic neoplasm with atypia, brisk mitoses, microvascular proliferation, and necrosis. Immunohistochemistry was positive for GFAP and negative for IDH1 and BRAF V600E. Loss of ATRX expression and nuclear positivity for H3G34R confirmed a diagnosis of diffuse hemispheric glioma, H3G34 mutant, WHO Grade 4. The Ki67 proliferation index was 50%.

Figure 2.

Axial non-contrast CT scan of the brain showing a large postoperative tension cyst at the tumor resection site. The cyst is causing a significant midline shift (8 mm) and severe cerebral edema, leading to neurological deterioration and requiring urgent intervention.

Postoperative complication and management

On postoperative day 7, the patient developed altered sensorium, multiple seizures, and left-sided mydriasis. CT scan revealed a newly formed 5 × 4 cm cystic lesion in the tumor bed, causing 8 mm midline shift and perilesional edema (Fig. 3). Emergency percutaneous needle aspiration was performed, yielding 100 ml of brownish fluid under pressure. Due to the urgent clinical deterioration, no formal cerebrospinal fluid (CSF) analysis was performed on the aspirated fluid. The contents appeared brownish and under pressure, suggestive of proteinaceous material. The patient improved neurologically, with resolution of pupillary asymmetry and cessation of seizures. CT imaging confirmed near-total cyst resolution (Fig. 4). However, persistent cerebrospinal fluid (CSF) accumulation was observed on follow-up imaging. Due to the deep location of the resection cavity and the risk of recurrence, a cystoperitoneal shunt was placed. A programmable shunt valve was used to allow postoperative pressure adjustments. This approach was preferred over repeat aspiration or fenestration. At six-month follow-up, the patient remained asymptomatic, and MRI showed complete cyst resolution with no tumor recurrence (Fig. 5). A summary of the clinical course is shown in Table 1.

Figure 3.

3D-reconstructed imaging illustrating the posterior burr hole trajectory planned for precise percutaneous puncture and decompression of the symptomatic cyst. This approach was strategically selected to ensure minimal tissue disruption while effectively draining the cystic fluid.

Figure 4.

Post-drainage CT scan showing complete decompression of the cystic cavity, with resolution of the midline shift and significant reduction in cerebral edema. The brain parenchyma has re-expanded, and ventricular asymmetry has improved.

Figure 5.

Postoperative MRI (T2 SPACE image) obtained after gross total resection and cystoperitoneal shunt placement. The image confirms successful cyst resolution, absence of fluid re-accumulation, and normalization of intracranial structures, indicating a favorable long-term outcome.

Table 1.

Chronological summary of the patient’s clinical course, from initial presentation through treatment and follow-up

Timeline	Event
Day −60 to 0	Patient presented with headache, vomiting, and seizures.
Day 0	Surgical resection of left trigonal glioma performed.
Day 1	Postoperative CT showed no cyst formation.
Day 7	Neurological deterioration; CT revealed cystic lesion with midline shift.
Day 7	Emergency percutaneous cyst drainage performed.
Day 8+	Rapid clinical improvement post-drainage.
Week 2	Cystoperitoneal shunt placement.
Month 6	Follow-up MRI showed no recurrence and favorable outcome.

This case report was written in accordance with the updated SCARE 2025 guidelines^[3].

Discussion

Pathophysiology of postoperative cyst formation

Postoperative cyst formation following brain tumor resection is a rare but clinically significant complication, most commonly arising within the first few days to weeks after surgery. Multiple pathophysiological mechanisms have been proposed to explain this phenomenon, and in most cases, these mechanisms are likely to act synergistically.

Disruption of the blood–brain barrier (BBB) during surgical manipulation is a well-recognized initiating factor. BBB disruption allows leakage of plasma proteins, inflammatory mediators (e.g., IL-6, TNF-α), and extracellular fluid, resulting in vasogenic edema, which may evolve into cystic cavitation if reabsorption fails^[1,4].

Another contributing factor is delayed hemorrhagic transformation or microhemorrhage at the resection site. These hemorrhagic events can degrade into hemosiderin-laden cystic fluid, generating local inflammatory responses and increasing osmotic gradients that favor cyst formation^[2].

In high-grade gliomas, vascular endothelial growth factor (VEGF) is often overexpressed, which increases vascular permeability and promotes secretion of extracellular fluid by residual tumor cells. This VEGF-mediated fluid accumulation is especially relevant in tumors with a high proliferative index, such as H3G34-mutant gliomas^[5,6].

Importantly, as highlighted by Fujimori et al, certain surgical and iatrogenic factors can create a “valve-like mechanism,” a one-way flow system that traps cerebrospinal fluid (CSF) within the resection cavity. This mechanism may involve the interplay between residual cerebral tissue, hemostatic agents like Surgicel, and arachnoid structures that block the egress of CSF while allowing ingress. Such a configuration may contribute to progressive cystic expansion despite the absence of infection or hemorrhage^[7].

Furthermore, low-pressure CSF diversion systems, such as ventriculoperitoneal (VP) shunts set at low opening pressures (e.g., 8 mmHg), may inadvertently facilitate fluid influx into the cavity, thereby enlarging the cyst – a mechanism observed in the same report^[8].

Risk factors for postoperative cyst formation

Multiple clinical and surgical variables have been associated with an increased likelihood of postoperative cyst development:

In pediatric patients, the risk of cyst formation post-resection is less well-documented compared to adults. Available literature suggests a lower incidence in children, potentially due to differences in tumor biology and immune responses. Moreover, management strategies are often adapted from adult protocols, highlighting the need for pediatric-specific data and guidance.

1. Tumor location and type: Tumors in periventricular or deep regions increase the risk due to proximity to CSF pathways and higher potential for partial resections^[6].

2. Histological grade: High-grade gliomas, especially those with a high Ki67 index, demonstrate aggressive behavior and are more prone to postoperative fluid accumulation due to increased angiogenesis and secretory activity^[7].

3. Extent of resection: Incomplete resections may leave secretory tumor remnants capable of continuous fluid production^[5].

4. Use of implants: The implantation of BCNU (carmustine) wafers in the resection cavity has been repeatedly linked to cyst formation, likely via local inflammatory responses and osmotic gradients^[4,5,7].

5. Microenvironmental inflammation: Cytokine-mediated vascular permeability from IL-6 and TNF-α exacerbates peritumoral fluid leakage and cystic changes^[8].

6. Iatrogenic valve formation: Application of hemostatic agents or surgical reconstruction materials can unintentionally compartmentalize the tumor bed, leading to a “valve-like” effect that promotes unidirectional fluid accumulation^[8,9].

Management strategies

The therapeutic approach depends on cyst size, symptom burden, and the risk of neurological deterioration.

1. Conservative monitoring: Asymptomatic or minimally symptomatic cysts with no mass effect can be followed conservatively with serial imaging. Spontaneous resolution has been reported, particularly when communication with CSF spaces is maintained^[2,9].

2. Percutaneous aspiration: Ideal for acute decompression, particularly in cases with rapid neurological deterioration. However, recurrence is common unless followed by definitive drainage procedures^[3].

3. Cyst fenestration: Endoscopic or open fenestration may create durable communication between the cyst cavity and adjacent cisterns or ventricles. This is especially useful when anatomical barriers impede spontaneous drainage^[6].

4. Cystoperitoneal shunting: Cystoperitoneal Shunting: This technique provides continuous drainage of cystic fluid and is effective in recurrent or persistent cysts. It has shown favorable outcomes, including in pediatric and high-grade glioma cases^[10]. In cases where anatomical communication with CSF pathways is feasible, endoscopic fenestration may also be considered as an alternative, particularly when shunt-related complications are a concern.

5. Valve/barrier resection: As described by Yu et al and Talacchi et al, surgical excision of valve-like obstructions (formed by Surgicel, arachnoid flaps, or cerebral tissue) can relieve pressure and re-establish physiological CSF circulation^[10,11].

Long-term considerations and follow-up

Given that cyst recurrence can occur weeks or months postoperatively, close clinical and radiologic monitoring is essential. Cases have been reported in which patients experienced delayed symptoms due to reaccumulation of fluid after apparent initial recovery^[9,10].

Advanced neuroimaging techniques, such as MR spectroscopy (MRS) and diffusion tensor imaging (DTI), may help differentiate metabolically active, fluid-producing tissue from inert postoperative cavities. This distinction could facilitate timely intervention before symptomatic recurrence^[12].

In the present case, Constructive Interference in Steady State (CISS) MRI sequences were not acquired; however, future cases could benefit from such high-resolution imaging to better characterize cyst content and anatomical continuity with ventricular structures.

Additionally, spinal MRI screening may be warranted in select cases – particularly where dissemination through CSF or metastatic seeding is suspected. Although rare, this complication has been documented in postoperative cystic tumor beds^[13].

Limitations

As a single-patient case report, generalizability is limited. The findings, while informative, require validation through larger pediatric series or systematic studies.

Clinical lessons

This case illustrates the need for early imaging to detect postoperative complications, the efficacy of minimally invasive drainage and shunting, and the importance of tailored management decisions in pediatric neurosurgical care. It reinforces the necessity for pediatric-specific guidelines in rare but impactful postoperative scenarios.

Future directions

There remains no universally accepted treatment guideline for managing postoperative cyst formation. Future studies should aim to:

1. Standardize protocols based on cyst size, location, and underlying pathology.

2. Investigate the use of anti-VEGF therapies like bevacizumab in reducing vascular permeability and fluid accumulation, especially in recurrent or refractory cases^[14,15].

3. Developing intraoperative strategies to minimize valve-like compartmentalization, such as controlled use of hemostatic agents and consideration of fenestration during primary resection.

4. Creating biomarker-based risk models to preoperatively identify patients at higher risk of cyst formation and tailor surgical planning accordingly^[16,17].

Conclusion

Postoperative cyst formation, though rare, represents a potentially life-threatening complication that requires early recognition and prompt management. Immediate postoperative imaging is crucial to rule out hemorrhage and monitor for fluid accumulation. Minimally invasive interventions, such as percutaneous cyst drainage and cystoperitoneal shunting, have shown to be effective in managing acute and recurrent cases. Long-term success depends on careful follow-up, patient-specific decision-making, and multidisciplinary coordination. Future research should aim to define standardized treatment protocols, explore pharmacologic adjuncts like anti-VEGF agents, and integrate advanced imaging and biomarkers into clinical workflows to improve patient outcomes.

Ethical approval

Ethical approval not required for case report.

Consent

Written informed consent was obtained from the patient legal guardian for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Sources of funding

Not applicable.

Author contributions

G.S., G.E.U., and B.C.: study concept or design, data collection, data analysis or interpretation; R.P..: writing the paper.

Conflicts of interest disclosure

No conflict of interest.

Guarantor

Bipin Chaurasia.

Research registration unique identifying number (UIN)

None.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability statement

Not applicable.