A Rare Presentation of Ruptured Pineal Region Teratoma with Postoperative Aseptic Meningitis

Abstract

Introduction

Mature teratomas are germ cell tumors composed of tissues derived from all three germ layers. These tumors are rare in the central nervous system, primarily occurring in the suprasellar and pineal regions. Rupture of intracranial teratomas is an exceptionally rare phenomenon, typically presenting on imaging as disseminated fatty droplets and occasionally associated with aseptic meningitis. We describe a case of a ruptured cystic teratoma in the pineal region, manifesting postoperatively with severe neurological symptoms consistent with aseptic meningitis.

Case Presentation

A 15-year-old boy presented with a 2-month history of persistent headaches. Computed tomography revealed a calcified mass lesion in the pineal region with low-density areas in the lateral ventricles. Magnetic resonance imaging (MRI) demonstrated a complex lesion in the pineal region and high T1 signal intensity bilaterally in the anterior horns of the lateral ventricles, suggestive of a ruptured teratoma. The patient underwent surgical resection. Postoperatively, he developed mild fever, severe headache, ocular pain, decreased vision, diplopia, and neck rigidity. Contrast-enhanced MRI revealed faint meningeal enhancement, consistent with aseptic meningitis. Symptoms gradually improved with steroid therapy.

Conclusion

This case underscores the importance of recognizing rupture as a potential complication of intracranial teratomas, which may result in severe postoperative aseptic meningitis. Intraoperative measures, such as meticulous irrigation, are critical to mitigate this rare but serious complication.

Introduction

Mature teratomas are germ cell tumors composed of tissues derived from the three germ layers: ectoderm, mesoderm, and endoderm. Within the central nervous system (CNS) [1], these tumors predominantly arise in the suprasellar and pineal regions. Rupture of tumors with dissemination of fatty droplets on imaging is well documented in cases of dermoid cysts, which are occasionally complicated by aseptic meningitis [2]. While ruptured mature teratomas have been reported in the ovary [3], their occurrence within the cranium is exceedingly rare [4]. Furthermore, postoperative aseptic meningitis associated with intracranial mature teratomas has not been previously reported. Here, we present a rare case of a ruptured mature teratoma in the pineal region, complicated by severe neurological symptoms indicative of aseptic meningitis in the postoperative period.

Case Presentation

History and Presentation

A 15-year-old boy with a history of pediatric epilepsy presented to his primary physician with a 2-month history of persistent headaches. Magnetic resonance imaging (MRI) revealed a tumor in the pineal region, leading to his referral to our hospital. Neurological examination revealed no deficits, and fundoscopic evaluation showed no evidence of papilledema. Computed tomography demonstrated a calcified tumor in the pineal region with hypodense areas in the lateral ventricles (Fig. 1). MRI identified a 1.5-cm tumor with partial hyperintensity on T1-weighted images and heterogeneous enhancement after contrast administration (Fig. 2a). High-signal intensity areas were observed bilaterally in the lateral ventricles, which attenuated on fat-suppressed sequences (Fig. 2b). These findings suggested a preoperative diagnosis of a ruptured teratoma in the pineal region.

Fig. 1.

Preoperative non-contrast CT scan. The CT demonstrated a calcified tumor in the pineal region (arrow heads) with hypodense areas (arrows) in the ventricles, which were presumed to represent fat components. CT, computed tomography.

Fig. 2.

a Preoperative gadolinium-enhanced T1-weighted MRI: left – axial view; right – sagittal view. b Preoperative non-contrast MRI: left – T1-weighted image; right – T1-weighted fat-suppressed image. A 1.5-cm tumor with partial hyperintensity on T1-weighted images and heterogeneous enhancement after contrast administration was identified (dashed circles). High-signal intensity areas were observed bilaterally in the lateral ventricles, which attenuated on fat-suppressed sequences (arrows).

Operation

The patient underwent surgery under general anesthesia in the prone position, with the head slightly rotated to the left. A right occipital craniotomy was performed using an occipital trans-tentorial approach to access the tumor. The tumor appeared pearly and was relatively soft, containing yellow, viscous material that was easily aspirated. Gross total resection was achieved, and the surgical field was irrigated with 500 mL of artificial cerebrospinal fluid to minimize the risk of aseptic meningitis.

Pathological Findings

Histopathological examination revealed fragments of fibrous tissue intermixed with keratinized stratified squamous epithelium, thyroid tissue, sebaceous and apocrine glands, respiratory epithelium, cartilage, calcification, and CNS tissue containing glial cells. These findings confirmed the diagnosis of a mature teratoma.

Postoperative Course

Immediately following surgery, the patient experienced severe headache, photophobia, decreased vision, and visual field disturbances. His body temperature remained at approximately 37°C, and neck rigidity was noted. Contrast-enhanced MRI demonstrated complete tumor resection and diffuse meningeal enhancement (Fig. 3a, b), findings suggestive of meningitis of some kind. However, considering the immediate postoperative context, infectious meningitis was deemed unlikely. Instead, the symptoms and the MRI findings were interpreted as aseptic meningitis secondary to the intraoperative dissemination of fat components. Intravenous steroid therapy with betamethasone was initiated on postoperative day 1, at a dose of 8 mg/day for 2 days, followed by gradual tapering and discontinuation. The patient’s headache and photophobia improved significantly by day 10, and his decreased vision and visual field disturbances resolved over the following 2 weeks.

Fig. 3.

a Postoperative gadolinium-enhanced T1-weighted MRI: left – axial view; right – sagittal view. b Postoperative T1-weighted MRI: left – non-contrast image; right – gadolinium-enhanced image. The tumor was resected completely (dashed circles), and faint meningeal enhancement was observed (arrow heads).

As his visual field deficits improved, he reported mild diplopia when looking downward to the left and right. We hypothesize that the severe headache, photophobia, decreased vision, and neck rigidity were primarily due to aseptic meningitis. In contrast, the hemianopsia and diplopia were likely attributable to intraoperative manipulation of the occipital lobe and midbrain tegmentum, respectively. Finally, the diplopia resolved completely.

Discussion

Intracranial teratomas are rare, constituting approximately 0.5% of all intracranial tumors and 2–4% of pediatric intracranial tumors [5]. These tumors originate from multipotential germ cells derived from all three germ layers, mimicking normal organogenesis [1]. The 2021 WHO Classification of CNS Tumors categorizes intracranial teratomas into three subtypes: mature, immature, and teratomas with malignant transformation [6]. While mature teratomas are generally benign, their potential to rupture, particularly in the CNS, is not well documented, with only a few reported cases [4, 7, 8].

In contrast, rupture of intracranial dermoid cysts is well characterized, with a rupture frequency of 49.3% reported by Chung et al. [9]. Rupture of dermoid cysts leads to dissemination of fatty content into the subarachnoid space, causing complications such as hydrocephalus, cerebral vasospasm, and aseptic meningitis. The mechanism of rupture in dermoid cysts is typically attributed to tumor enlargement due to hormone-dependent secretion or trauma [9]. However, systematic studies on the rupture of intracranial teratomas are lacking, with only sporadic reports describing cases in the posterior cranial fossa and lumbar spinal cord [4, 10, 11]. These cases often demonstrate free fatty material in the ventricles, as observed in our patient.

Extracranial teratoma rupture, particularly in the ovaries and mediastinum, is better understood [3, 12]. A review of 350 cases of ovarian mature teratomas in children reported preoperative rupture in 2% and perioperative rupture in 6% of cases [3]. Sasaka et al. [12] identified contributing factors such as chronic inflammation, endogenous enzyme secretion, sebaceous gland activity, ischemia, and rapid tumor growth leading to thinning of the tumor wall. These mechanisms, elucidated in mediastinal teratomas, may provide insights into the pathogenesis of intracranial teratoma rupture.

In the present case, the patient’s initial symptom was a prolonged mild headache that progressed postoperatively to severe headache, neck stiffness, photophobia, and decreased vision. MRI findings of faint leptomeningeal enhancement were consistent with aseptic meningitis, likely caused by the leakage of tumor contents, including fatty material. Similar inflammatory mechanisms have been observed in ruptured craniopharyngiomas, where cholesterol crystals in cystic fluid elicit a severe inflammatory response [13]. Meticulous irrigation of the surgical field with artificial cerebrospinal fluid is critical to reducing the risk of aseptic meningitis [14]. Steroid therapy, as demonstrated in this case, can be effective; the patient’s symptoms improved gradually with intravenous betamethasone, tapered over 10 days.

We report a rare case of a ruptured mature teratoma in the pineal region. While intracranial teratomas are uncommon, their potential to rupture and cause postoperative aseptic meningitis should be recognized. Preventive measures during surgery are essential. Further research is needed to elucidate the detailed pathogenesis of intracranial teratoma rupture and establish optimal management strategies. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000546099).

Statement of Ethics

Ethical approval was not required for this study, in accordance with local and national guidelines. Informed assent for publication of the details of their medical case and any accompanying images was obtained from the patient, and written informed consent for the same was obtained from the legal guardian of the patient.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

This study was not supported by any sponsor or funder.

Author Contributions

K.F. performed data collection, analysis, manuscript drafting, and figure preparation. T.Y. contributed to the study’s conception and design and critically revised the manuscript for intellectual content. T.Y., M.S., I.T., Y.T., K.T., and N.H. contributed to the decision-making process for the treatment plan and the actual treatment, and approved the final manuscript.

Funding Statement

This study was not supported by any sponsor or funder.

Data Availability Statement

The data supporting the findings of this case report are securely stored in the electronic medical records of Kyoto Prefectural University of Medicine and consist of patient-specific information. Due to privacy and ethical restrictions, the data are not publicly available. Further inquiries can be directed to the corresponding author.