Physiological alterations of pineal recess crowding in symptomatic non-hydrocephalic pineal cysts

Pineal cysts are prevalent in the population. Due to more widespread use of magnetic resonance imaging, an increasing number of symptomatic patients with non-hydrocephalic pineal cysts are referred to neurologists and neurosurgeons. Currently, there is no generally accepted theoretical framework for linking symptoms to a pineal cyst. We have previously suggested that cyst-induced crowding of the pineal recess may affect venous runoff from the deep cerebral veins crossing the cyst. However, evidence underpinning this hypothesis is sparse. In the present study, we asked whether crowding of the pineal recess without imaging signs of hydrocephalus may be accompanied with alterations in blood flow of the internal cerebral veins, cerebrospinal fluid flow in the Sylvian aqueduct and cerebrospinal fluid-mediated tracer clearance from the brain along extravascular pathways (referred to as glymphatic function). This prospective, observational study included symptomatic individuals with non-hydrocephalic pineal cysts who underwent a standardized magnetic resonance imaging protocol (n = 25): Eleven patients were treated surgically with craniotomy and cyst extirpation and 14 individuals were managed conservatively without surgery. Our findings suggest that cyst-induced crowding of the pineal recess may have brain-wide effects: (i) There was a significant negative correlation between degree of crowding within the pineal recess and change in maximum venous flow velocity at the cyst, and a significant positive correlation between maximum venous flow velocity change at the cyst and net cerebrospinal fluid flow in the Sylvian aqueduct; (ii) increased degree of crowding in the pineal recess was accompanied by significantly impaired glymphatic enrichment in the cerebral cortex and subcortical white matter, indicative of a brain-wide effect in this cohort who also reported markedly impaired subjective sleep quality; (iii) there was a significant negative correlation between the apparent diffusion coefficient (suggestive of interstitial water content) within the thalamus and glymphatic enrichment of tracer and (iv) pineal recess crowding associated with symptoms. Comparison of the surgical cases [in whom 10/11 (91%) reported marked clinical improvement at follow-up] and the conservatively managed cases [in whom 1/14 (7%) reported marked clinical improvement at follow-up] showed differences in pre-treatment glymphatic tracer enrichment as well as differences in tracer enrichment in subarachnoid cerebrospinal fluid spaces. Taken together, we interpret these observations to support the hypothesis that cyst-induced crowding of the pineal recess without hydrocephalus may alter blood flow of the internal cerebral veins and cerebrospinal fluid flow and even cause brain-wide impairment of glymphatic transport with possible implications for cerebrospinal fluid transport of trophic factors such as melatonin.

Pineal cysts without hydrocephalus: microsurgical resection via an infratentorial-supracerebellar approach-surgical strategies, complications, and their avoidance

Indications for surgery of pineal cysts without ventriculomegaly are still under debate. In view of the limited data for pineal cyst resection in the absence of hydrocephalus, and the potential risk of this approach, we have analyzed our patient cohort focusing on strategies to avoid complications according to our experience in a series of 73 pineal cyst patients. From 2003 to 2015, we reviewed our database retrospectively for all patients operated on a pineal cyst. Furthermore, we prospectively collected patients from 2016 to 2020. In summary, 73 patients with a pineal cyst were treated surgically between 2003 and 2020. All patients were operated on via a microscopic supracerebellar-infratentorial (SCIT) approach. The mean follow-up period was 26.6 months (range: 6-139 months). Seventy-three patients underwent surgery for a pineal cyst. An absence of enlarged ventricles was documented in 62 patients (51 female, 11 male, mean age 28.1 (range 4-59) years). Main presenting symptoms included headache, visual disturbances, dizziness/vertigo, nausea/emesis, and sleep disturbances. Complete cyst resection was achieved in 59/62 patients. Fifty-five of 62 (89%) patients improved after surgery with good or even excellent results according to the Chicago Chiari Outcome Scale, with complete or partial resolution of the leading symptoms. Pineal cysts resection might be an indication in certain patients for surgery even in the absence of ventriculomegaly. The high percentage of postoperative resolution of quality-of-life impairing symptoms in our series seems to justify surgery. Preoperatively, other causes of the leading symptoms have to be excluded.

In and around the pineal gland: a neuroimaging review

Lesions arising in or around the pineal gland comprise a heterogeneous group of pathologies ranging from benign non-neoplastic cysts to highly malignant neoplasms. Pineal cysts are frequently encountered as an incidental finding in daily radiology practice but there is no universal agreement on the criteria for, frequency of, and duration of follow-up imaging. Solid pineal neoplasms pose a diagnostic challenge owing to considerable overlap in their imaging characteristics, although a combination of radiological appearances, clinical findings, and tumour markers allows for narrowing of the differential diagnosis. In this review, we describe the radiological anatomy of the pineal region, clinical symptoms, imaging appearances, and differential diagnosis of lesions arising in this area, and highlight the clinical management of these conditions.

Pineal cysts: Does anyone need long-term follow up?

Pineal cysts are a common incidental finding on brain magnetic resonance imaging (MRI) whichfrequently prompts referral to neurosurgery. Currently, a management algorithm for patientswithout hydrocephalus, Parinaud's syndrome, or pineal apoplexy is lacking.We aimed to identifypredictive factors of pineal cyst volume change andsurgical intervention by performing retrospective chart review of 98 patients between 2005 and 2018 diagnosed with pineal cysts gleaned from our Neurosurgery clinical databases.We included patients whose initial and follow-up MRIs were available in our institutional radiology system or whose surgical pathology confirmed pineal cyst after evaluation with an initial MRI. Patients' medical records were queried for presenting symptoms, demographic, management, and pineal cyst measurements. Three dimensions (anterior-posterior, rostral-caudal, transverse) of pineal cyst size were measured and converted to cyst volume (cm³) for analysis. Fifty-five patients (mean age 26.09 ± 14.7 years) with pineal cysts met study criteria. Follow-up ranged from 4 months to 10 years. The indications for MR imaging included headache (81.8%) and vision problems (42%).Forty-eight patients who were observed had a mean volume change of 0.051 ± 0.862 cm [3] and median volume change of 0 cm [3] Patient symptoms, referral source, and age were not associated with changes in volume on follow-up. Aggregated number of symptoms did not differ between operative and observation patients. (p = 0.29). Pineal cyst volumes tend to remain stable over serial MR images, do not reliably correlate with symptoms, and do not typically require long-term follow-up.

Headache outcomes after surgery for pineal cyst without hydrocephalus: A systematic review

Background:

Pineal cysts are common entities, with a reported prevalence between 10 and 54%. Management of pineal cysts has historically been expectant, with surgical treatment of these lesions usually reserved for patients with a symptomatic presentation secondary to mass effect. The appropriate management of pineal cysts in patients presenting with headache in the absence of hydrocephalus – often the most common clinical scenario – has been more ambiguous. Here, we report the results of a comprehensive systematic review of headache outcomes for surgically treated, non-hydrocephalic pineal cyst patients without signs of increased intracranial pressure (ICP).

Methods:

Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to construct a systematic review. A comprehensive search of the PubMed, Embase, Scopus, and Web of Science databases was conducted from through June 2020. Relevant English-language articles were identified using the search terms “pineal cyst” and “headache.” The following eligibility criteria were applied: the inclusion of at least one surgically-treated, non-hydrocephalic pineal cyst patient presenting with headache in the absence of hemorrhage or signs and symptoms of increased ICP. Patient demographics and post-operative headache outcomes for the included studies were extracted and summarized.

Results:

A total of 24 pineal cyst cases meeting our selection criteria were identified across 11 included studies. Postoperative improvement or resolution of headaches was reported for 23/24 patients. Our systematic review of the literature demonstrates that non-hydrocephalic patients with pineal cysts have a high rate of headache improvement following surgical intervention.

Conclusion:

The results indicate a need for further investigation of the link between headache and pineal cysts in the non-hydrocephalic patient.

Unusual Brain MRI Findings in Patients Imaged for Headache: a Case Series

PURPOSE OF REVIEW

We describe a series of cases with unusual brain MRI findings in patients who present with headache disorders.

RECENT FINDINGS

Incidental findings in patients imaged for headache include the following: aneurysm, arachnoid cyst, cerebral vascular malformations, Arnold-Chiari malformations, empty sella turcica, gray matter heterotopias, mastoiditis, mega cisterna magna, meningioma, normal variants of cerebral circulation, paranasal sinus disease, pineal cyst, pituitary tumor, Rathke's cleft cyst, skull hyperostosis, and vestibular schwannoma. The most common abnormal MRI findings encountered in migraine are nonspecific white matter lesions. The current 2019 guidelines from the American College of Radiology and American Headache Society recommend against ordering neuroimaging in patients with a high probability of a primary headache disorder not typically associated with diagnostic imaging findings and who have normal neurologic exam in addition to no red flags in history. Often, unnecessary neuroimaging yields incidental findings, and this typically results in patient anxiety and further unnecessary testing. Detailed below are a series of cases in which unusual findings were found in patients presenting to our clinic for further evaluation of headache disorders. Imaging may have been done prior to presentation to us or by us due to concern for secondary causes.

Current understanding of pineal gland structure and function in headache

PURPOSE

The pineal gland plays an important role in biological rhythms, circadian and circannual variations, which are key aspects in several headache disorders.

OVERVIEW

Melatonin, the main pineal secreting hormone, has been extensively studied in primary and secondary headache disorders. Altered melatonin secretion occurs in many headache syndromes. Experimental data show pineal gland and melatonin both interfere in headache animal models, decreasing trigeminal activation. Melatonin has been shown to regulate CGRP and control its release.

DISCUSSION

Melatonin has been used successfully as a treatment for migraine, cluster headaches and other headaches. There is a rationale for including the pineal gland as a relevant brain structure in the mechanisms of headache pathophysiology, and melatonin as a treatment option in primary headache.

Pineal gland abnormality in major depressive disorder

Patients with major depressive disorder (MDD) often have circadian rhythm alteration and sleep disturbance. The pineal gland regulates the circadian rhythm and sleep by the secretion of melatonin neurohormone. However, the relationship between pineal abnormality and MDD remains elusive. 50 patients with MDD and 35 gender- and age-matched healthy controls underwent high-resolution structural MRI. Pineal parenchymal volume (PPV) was measured manually. Inter-group differences in prevalence of pineal cyst and PPV were examined. In addition, we investigated the correlations between PPV and symptom severity as well as sleep variables in the patient group. Compared to healthy controls, patients with MDD had a higher prevalence of pineal cyst. Moreover, patients had significantly decreased PPV relative to controls. However, no significant correlations were observed between PPV and symptom severity as well as sleep variables. Our findings suggest that pineal abnormality may play a critical role in depression.

Pineal Cyst-Related Aqueductal Stenosis as Cause of Intractable Headaches in Nonhydrocephalic Patients

BACKGROUND

Pineal cysts (PCs) are histologically benign lesions of the pineal gland. Although the majority of PCs are asymptomatic, some cases are ambiguous and accompanied by nonspecific symptoms of variable severity. We suggested that disabling headache in nonhydrocephalic patients with PCs is associated with cerebral aqueduct (CAq) stenosis.

METHODS

A retrospective analysis was conducted in patients with PCs suffering from headache without secondary hydrocephalus who underwent surgical resection at Burdenko Neurosurgery Center between 1995 and 2016. All available medical records and radiographic images were retrospectively assessed in these patients. The comparison groups included 22 patients with nonoperated PCs and 25 healthy individuals. Specific magnetic resonance imaging measures were selected to assess the morphometry of the CAq and degree of the stenosis.

RESULTS

In 25 patients (82%) we observed clinical improvement after surgery in a follow-up period. Among those with improvement, 10 of them (40%) experienced total relief and 15 of them (60%) had marked headache diminishment. In 5 patients the headache remained persistent. The preoperative rostral CAq diameter appeared to be significantly narrower (P = 0.0011045), and the preoperative rostral/caudal diameter ratio (Rd/Cd) was found to be lower (P = 0.004391) in patients who recovered from headache versus those who did not.

CONCLUSION

The results indicate a statistically significant relationship between the changes in the CAq morphometrics and the clinical outcome in postoperative period. Surgical removal of symptomatic pineal cysts in patients without hydrocephalus can be considered as an effective treatment. However, a thorough preoperative examination and patient selection should be conducted in every case.

Sleep disorders in children with incidental pineal cyst on MRI: a pilot study

INTRODUCTION

For several years, pineal cysts have been considered an incidental finding on brain MRI's even though research and case reports have shown a possible association of pineal cysts with headaches and sleep disturbances. This pilot study aims to evaluate sleep disorders in school-age children with an incidental pineal cyst in an otherwise normal brain MRI.

METHOD

Children aged 6-12 years, who were referred for evaluation of headaches, tics, or syncope, and had an incidental pineal cyst on an otherwise normal brain MRI were included and compared to a control group of children with the same referral reasons but with a normal MRI and to a cohort of normal controls. The Sleep Disturbance Scale for Children (SDSC) was administered to the parents. Exclusion criteria included use of medications that affect sleep, seizures, brain abnormalities, tumors, or comorbid medical conditions that affect sleep.

RESULTS

Eighteen children (11 females) with pineal cysts, 19 children with normal MRI, and 100 age- and sex-matched controls were included in our study. There were statistically significant differences in the total SDSC score (with a difference of 10 between the median scores) and in two of the six domains of this scale. Children with pineal cysts scored significantly higher in the domains of disorders of excessive sleepiness and disorders of initiating and maintaining sleep than the two control groups. The scores in these two domains correlated significantly with the size of the cyst.

CONCLUSION

School-age children with pineal cysts have significantly increased levels of sleepiness and difficulty with sleep initiation and maintenance.

Incidental Findings and Normal Anatomical Variants on MRI of the Brain in Adults for Primary Headaches

When MRI scans of the brain are obtained for evaluation of primary headaches in adults, incidental findings are commonly present. After a review of the prevalence of incidental findings and normal anatomical variants, 21 types are presented.

[Pineal cyst]

A pineal cyst (PC) is a benign neoplasm in the pineal region, or more precisely in the pineal body. Most cysts are incidental findings and are not associated with symptoms typical of patients seeking medical advice. Symptomatic cysts are discovered less often and, depending on the clinical picture, require different treatment approaches.

MATERIAL AND METHODS

We analyzed the literature data about the clinical picture, diagnosis, and treatment of PCs for more than a century (1914-2016).

CONCLUSION

To date, there is no single approach for managing PC patients. The indications for surgical treatment of symptomatic PCs are still not fully defined. It remains unclear which PC cases should be followed-up, and how often control examinations should be performed. More research of PCs is needed to develop new approaches to treatment of PC patients.

Pineal cysts and other pineal region malignancies: determining factors predictive of hydrocephalus and malignancy

OBJECTIVE Cystic lesions of the pineal gland are most often uncomplicated benign lesions with typical MRI characteristics. The authors aimed to study pineal lesion characteristics on MRI to better distinguish benign pineal cysts from other pineal region malignancies as well as to determine which characteristics were predictive of the latter malignancies. They also aimed to study risk factors predictive of hydrocephalus or malignancy in patients harboring these lesions. METHODS The authors performed a retrospective review of a prospectively compiled database documenting the outcomes of patients with suspected pineal cysts on MRI who had presented in the period from 1998 to 2004. Inherent patient and lesion characteristics were assessed in a univariate logistic regression analysis to predict the following dependent variables: development of hydrocephalus, biopsy-confirmed malignancy, and intervention. Possible inherent patient and lesion characteristics included age, sex, T1 and T2 MRI signal pattern, contrast enhancement pattern, presence of cyst, presence of blood, complexity of lesion, presence of calcification, and duration of follow-up. Inherent patient and lesion characteristics that were predictive in the univariate analysis (p < 0.15) were included in the multivariable logistic regression analysis. RESULTS Of the 79 patients with benign-appearing pineal cysts, 26 (33%) were male and 53 (67%) were female, with a median age of 38 years (range 9-86 years). The median cyst radius was 5 mm (range 1-20 mm). Two patients (2.5%) had evidence of calcifications, 7 (9%) had multicystic lesions, and 25 (32%) had some evidence of contrast enhancement. The median follow-up interval was 3 years (range 0.5-13 years). Seven patients (9%) had an increase in the size of their lesion over time. Eight patients (10%) had a hemorrhage, and 11 patients (14%) developed hydrocephalus. Nine (11%) received ventriculoperitoneal shunts for the development of hydrocephalus, and 12 patients (16%) were found to have malignancies following biopsy or resection. In the multivariate analysis, contrast enhancement on MRI (OR 1.6, 95% CI 2.86-74.74, p = 0.013) and hemorrhage (OR 26.9, 95% CI 3.4-212.7, p = 0.022) were predictive of hydrocephalus. Increasing lesion size and hydrocephalus were near perfect predictors of malignancy and thus were removed from multivariate analysis. In addition, contrast enhancement on MRI (OR 8.8, 95% CI 2.0-38.6, p = 0.004) and hemorrhage (OR 6.8, 95% CI 1.1-40.5, p = 0.036) were predictive of malignancy. CONCLUSIONS Although cystic abnormalities of the pineal gland are often benign lesions, they are frequently monitored over time, as other pineal region pathologies may appear similarly on MRI. Patients with growing lesions, contrast enhancement, and hemorrhage on MRI are more likely to develop hydrocephalus and have malignant pathology on histological examination and should therefore be followed up with serial MRI with a lower threshold for neurosurgical intervention.

Incidental Pineal Cysts: Is Surveillance Necessary?

OBJECTIVE

The natural history of incidental pineal cysts is poorly understood. Neurosurgeons and neuroradiologists are more frequently faced with this disease in the advent of higher-resolution magnetic resonance imaging (MRI) scanning. We aim to suggest a suitable surveillance strategy for these patients.

METHODS

All patients who had MRI of the brain between June 2007 and January 2014 (n = 42,099) at The Walton Centre for Neurology and Neurosurgery were included. Radiologic reports containing the terms "pineal" and "cyst" were reviewed to identify patients.

RESULTS

A total of 281 patients were identified with pineal cysts. The principal indication for head MRI was headache (50.2%), although no symptoms were deemed attributable to pineal disease. A total of 178 patients (63.3%) were female, and the age at diagnosis ranged from 16 to 84 years. The median size of pineal cyst at diagnosis was 10 mm. A total of 181 patients had subsequent follow-up at a median time of 6 months (range, 1-68). Eleven pineal cysts (6%) changed size during the follow-up period. Four patients had a reduction in cyst size; the median change was 2.5 mm. A further 7 pineal cysts increased in cyst size; the median change was 2 mm. No patients developed complications.

CONCLUSIONS

Incidental pineal cysts typically show a benign course. In the adult population, they do not require long-term neurosurgical follow-up, because pineal cysts tend to remain a stable size. In asymptomatic patients, we recommend a single follow-up MRI scan at 12 months to confirm diagnosis. The patient should then be discharged if the cyst remains stable.

Magnetic resonance imaging biomarkers indicate a central venous hypertension syndrome in patients with symptomatic pineal cysts

BACKGROUND

While most pineal cysts (PCs) are asymptomatic, some PCs are accompanied with symptoms of variable severity. We suggested that symptom severity in symptomatic patients with non-hydrocephalic PCs relates to venous compression causing central venous hypertension. This study explored whether possible magnetic resonance imaging (MRI) biomarkers of central venous hypertension could differentiate the severity of symptoms in individuals with non-hydrocephalic PCs.

METHODS

The study included all individuals with PCs and MRI available for analysis followed conservatively within the department from 2003 to 2014. Severity of symptoms at follow-up were assessed from a questionnaire. Suggested MRI biomarkers indicative of central venous hypertension were explored, in addition to MRI measures of cyst size, aqueduct stenosis, and tectal compression.

RESULTS

The study included 66 patients. As compared to the 27/66 patients (41%) with "None-Moderate" symptoms at follow-up, the 39/66 patients (59%) with "Much-Severe" symptoms presented with significantly altered indices of central venous hypertension (tectum-splenium-cyst ratio and indices of thalamic and periventricular edema). PC grading based on MRI biomarkers of central venous hypertension differentiated the severity of symptoms.

CONCLUSION

The results indicate an association between severity of symptoms and MRI biomarkers of central venous hypertension in symptomatic individuals with non-hydrocephalic PCs.

Pineal cyst resection in the absence of ventriculomegaly or Parinaud's syndrome: clinical outcomes and implications for patient selection

OBJECT

Surgical indications for patients with pineal cysts are controversial. While the majority of patients harboring a pineal cyst require no treatment, surgery is a well-accepted option for a subset of those patients with secondary hydrocephalus or Parinaud's syndrome. The majority of pineal cysts are identified incidentally during workup for other potential conditions, which may or may not be related to the presence of the cyst. In the absence of clear obstruction of CSF pathways, the treatment of presumed symptomatic pineal cysts is debatable. To clarify the role of surgery in these borderline cases, the authors reviewed their experience with resection of pineal cysts in the absence of ventriculomegaly or Parinaud's syndrome.

METHODS

The authors retrospectively reviewed medical records and imaging of all patients surgically treated between 2001 and 2014 with a pineal cyst in the absence of ventriculomegaly and Parinaud's syndrome. The presenting symptoms, preoperative cyst size, preoperative radiographic aqueductal compression, extent of resection, and radiographic and clinical follow-up were documented.

RESULTS

Eighteen patients (14 female and 4 male; mean age 24 years, range 4–47 years) underwent cyst resection in the absence of ventriculomegaly or Parinaud's syndrome. Presenting symptoms included headache (17 patients), visual disturbances (10 patients), gait instability (5 patients), dizziness (5 patients), episodic loss of consciousness (2 patients), and hypersomnolence (1 patient). The mean preoperative cyst diameter was 1.5 cm (range 0.9–2.2 cm). All patients had a complete resection. At a mean clinical follow-up of 19.1 months (range postoperative to 71 months), 17 (94%) patients had resolution or improvement of their presenting symptoms.

CONCLUSIONS

The authors' results suggest that ventriculomegaly and Parinaud's syndrome are not absolute requisites for a pineal cyst to be symptomatic. Analogous to colloid cysts of the third ventricle, intermittent occlusion of cerebrospinal fluid pathways may cause small pineal cysts to become intermittently symptomatic. A select cohort of patients with pineal cysts may benefit from surgery despite a lack of hydrocephalus or other obvious compressive pathology.

Update on the management of pineal cysts: Case series and a review of the literature

OBJECTIVE

The natural history of pineal cysts still remains unclear. Incidental pineal cysts have become more common which raises the question of their management. Symptomatic pineal cysts may require a surgical solution but therapeutic indications have not yet been clearly established.

METHOD

From 1986 to 2012, 26 patients with pineal cysts were identified. Their medical records were retrospectively assessed focusing on the initial symptoms, imaging characteristics of the cyst, management strategy, operative technique and their complications, as well as the latest follow-up. A systematic review of the literature is also presented.

RESULTS

Twenty-six patients with pineal cysts were identified. The mean age was 23.5 years ranging from 7 to 49 years. Symptoms included intracranial hypertension with obstructive hydrocephalus in 18 cases and oculomotor anomalies in 12 cases. Two adult cases presented with non-specific headaches and did not require surgery. Twenty patients were operated via a suboccipital transtentorial approach with total removal of the cyst in 70% of the cases, while the remaining 4 cases were treated with an intraventricular endoscopic marsupialization associating a third ventriculostomy. Four patients required a preoperative ventriculo-peritoneal shunt due to life-threatening obstructive hydrocephalus. Overall, peri-operative mortality was nil. In the two non-operated patients, the cyst remained stable and no recurrences were observed in all operated patients with a mean follow-up of 144 months.

CONCLUSION

In the majority of incidental pineal cysts, a clinical and imaging follow-up is sufficient but occasionally not required especially in adults as very rare cases of increase in size have been reported.

Pineal cysts in children: case-based update

PURPOSE

Pineal cysts (PC) are found in children as often asymptomatic and without change in their size over the time. However, there are some debatable issues about their evolution and management in the pediatric population. The aim of the present paper is to update the information regarding pathogenesis, clinical presentation, and management of these lesions.

METHODS

All the pertinent literature was reviewed, and a meta-analysis of operated on cases was carried out. An illustrative case regarding the clinical evolution of a 13-year-old girl is also presented.

RESULTS AND CONCLUSIONS

PC are often asymptomatic and do not evolve over the time. However, since there is a certain risk of clinical and/or radiological progression, or even sudden and severe clinical onset (apoplexy), both a clinical and radiological follow-up is recommended in the pediatric age. The surgical excision is usually limited to symptomatic patients or to cases with clear radiological evolution.

Pineal cyst: a review of clinical and radiological features

Pineal cysts (PCs) are benign and often asymptomatic lesions of the pineal region that are typically small and do not change in size over time. PCs appear as small, well circumscribed, unilocular masses that either reside within or completely replace the pineal gland. This article reviews and discusses the characteristic features of PCs-clinical, histological, and identifiable by various imaging modalities-which assist clinicians in narrowing the differential diagnosis for pineal lesions.