Structural and ultrastructural characteristics of human pineal gland, and pineal parenchymal tumors

Understanding and Managing Pineal Parenchymal Tumors of Intermediate Differentiation: An In-Depth Exploration from Pathology to Adjuvant Therapies

BACKGROUND

Pineal parenchymal cell tumors constitute a rare group of primary central nervous system neoplasms (less than 1%). Their classification, especially the intermediate subtype (PPTIDs), remains challenging.

METHODS

A literature review was conducted, navigating through anatomo-pathological, radiotherapy, and neurosurgical dimensions, aiming for a holistic understanding of these tumors.

RESULTS

PPTIDs, occupying an intermediate spectrum of malignancy, reveal diverse histological patterns, mitotic activity, and distinct methylation profiles. Surgical treatment is the gold standard, but when limited to partial removal, radiotherapy becomes crucial. While surgical approaches are standardized, due to the low prevalence of the pathology and absence of randomized prospective studies, there are no shared guidelines about radiation treatment modalities.

CONCLUSION

Surgical removal remains pivotal, demanding a personalized approach based on the tumor extension. This review underscores the considerable variability in treatment approaches and reported survival rates within the existing literature, emphasizing the need for ongoing research to better define optimal therapeutic strategies and prognostic factors for PPTIDs, aiming for further and more detailed stratification among them.

Pineal cysts in children: a paediatric series treated over the last twenty years in Lyon

BACKGROUND

Pineal cysts are a rare lesion of the pineal gland. Pineal cysts are benign lesions, generally asymptomatic, and are usually an incidental discovery on MRI performed for other problems. The management of pineal cysts in children remains a matter for debate. Here, we report our own retrospective paediatric cases that have been surgically treated and review the paediatric literature on this topic.

METHODS

This is a retrospective monocentric study. All patients operated by the senior author (CM) for a benign pineal cyst from 2000 to 2021 were included. All other pineal region cystic lesions were excluded. Medical and surgical data were extracted from the hospital medical database.

RESULTS

Twelve patients were included. The clinical symptomatology was characterized by headaches in seven patients, visual troubles in two patients, precocious puberty in one patient, signs of intracranial hypertension in two patients, seizures associated with headache in one patient, and headaches associated with behavioural troubles in another patient. No major post-operative complications were observed in this series. It is to noted that surgery was performed because a suspicion of a true pineal parenchymal tumour has been made. Histopathological study came back with the diagnosis of pineal cyst.

CONCLUSIONS

Pineal cyst is rare. If the radiological diagnosis is clear, no surgery is advocated except in cases associated with hydrocephalus and rapid growth. In case of a suspicion of a true pineal parenchymal tumour, a surgery may be needed to confirm the diagnosis. Lastly, we stress that only cystic lesions of the pineal gland itself should be considered as pineal cyst.

Histopathology and molecular pathology of pediatric pineal parenchymal tumors

Pineal parenchymal tumors in children are rare. They consist of two main types, pineoblastoma (PB) and pineal parenchymal tumor of intermediate differentiation (PPTID), which are World Health Organization (WHO) grade 4 and grade 2-3 respectively. PBs are divided into four distinct molecular groups: PB-miRNA1, PB-miRNA2, PB-RB1, and PB-MYC/FOXR2. PB-RB1 and PB-MYC/FOXR2 affect young children and are associated with a dismal prognosis. PB-miRNA1 and PB-miRNA2 groups affect older children and follow a more favorable course. They are characterized by mutually exclusive alterations in genes involved in miRNA biogenesis, including DICER1, DROSHA, and DGCR8. They may be sporadic or may represent one manifestation of DICER1 syndrome. PB-RB1 tumors show alterations in the RB1 gene and may develop in the setting of congenital retinoblastoma, a condition known as "trilateral retinoblastoma." In the pediatric population, PPTIDs typically affect adolescents. They are characterized by small in-frame insertions in the KBTBD4 gene which is involved in ubiquitination.

Pineal parenchymal tumor of intermediate differentiation: a systematic review and contemporary management of 389 cases reported during the last two decades

Pineal parenchymal tumor of intermediate differentiation (PPTID) is a WHO grade II and III tumor arising from pineal parenchymal cells. PPTID is a rare tumor accounting for less than 1% of all primary central nervous system neoplasms. Therefore, reports describing the clinical characteristics and biological features of PPTID are lacking. Moreover, the therapeutic strategy remains controversial. The current study aimed to evaluate treatment results and problems of contemporary therapeutic modalities of PPTID based on its features compared with other pineal parenchymal tumors. A comprehensive systematic literature review of 69 articles was performed, including articles on PPTID (389 patients) and similar tumors. Patient demographics, disease presentation, imaging characteristics, biological features, and current therapeutic options and their results were reviewed. We found that histopathological findings based on current WHO classification are well associated with survival; however, identifying and treating aggressive PPTID cases with uncommon features could be problematic. A molecular and genetic approach may help improve diagnostic accuracy. Therapeutic strategy, especially for grade III and aforementioned uncommon and aggressive tumors, remains controversial. A combination therapy involving maximum tumor resection, chemotherapy, and radiotherapy could be the first line of treatment. However, although challenging, a large prospective study would be required to identify ways to improve the clinical results of PPTID treatment.

Role of Aldynoglia Cells in Neuroinflammatory and Neuroimmune Responses after Spinal Cord Injury

Aldynoglia are growth-promoting cells with a morphology similar to radial glia and share properties and markers with astrocytes and Schwann cells. They are distributed in several locations throughout the adult central nervous system, where the cells of the aldynoglia interact and respond to the signals of the immune cells. After spinal cord injury (SCI), the functions of resident aldynoglia, identified as ependymocytes, tanycytes, and ependymal stem cells (EpSCs) of the spinal cord are crucial for the regeneration of spinal neural tissue. These glial cells facilitate axonal regrowth and remyelination of injured axons. Here, we review the influence of M1 or M2 macrophage/microglia subpopulations on the fate of EpSCs during neuroinflammation and immune responses in the acute, subacute, and chronic phases after SCI.

Mass-spectrometry analysis of the human pineal proteome during night and day and in autism

The human pineal gland regulates day-night dynamics of multiple physiological processes, especially through the secretion of melatonin. Using mass-spectrometry-based proteomics and dedicated analysis tools, we identify proteins in the human pineal gland and analyze systematically their variation throughout the day and compare these changes in the pineal proteome between control specimens and donors diagnosed with autism. Results reveal diverse regulated clusters of proteins with, among others, catabolic carbohydrate process and cytoplasmic membrane-bounded vesicle-related proteins differing between day and night and/or control versus autism pineal glands. These data show novel and unexpected processes happening in the human pineal gland during the day/night rhythm as well as specific differences between autism donor pineal glands and those from controls.

Systematic review of pineal cysts surgery in pediatric patients

INTRODUCTION

We present a consecutive case series and a systematic review of surgically treated pediatric PCs. We hypothesized that the symptomatic PC is a progressive disease with hydrocephalus at its last stage. We also propose that PC microsurgery is associated with better postoperative outcomes compared to other treatments.

METHODS

The systematic review was conducted in PubMed and Scopus. No clinical study on pediatric PC patients was available. We performed a comprehensive evaluation of the available individual patient data of 43 (22 case reports and 21 observational series) articles.

RESULTS

The review included 109 patients (72% females). Ten-year-old or younger patients harbored smaller PC sizes compared to older patients (p < 0.01). The pediatric PCs operated on appeared to represent a progressive disease, which started with unspecific symptoms with a mean cyst diameter of 14.5 mm, and progressed to visual impairment with a mean cyst diameter of 17.8 mm, and hydrocephalus with a mean cyst diameter of 23.5 mm in the final stages of disease (p < 0.001). Additionally, 96% of patients saw an improvement in their symptoms or became asymptomatic after surgery. PC microsurgery linked with superior gross total resection compared to endoscopic and stereotactic procedures (p < 0.001).

CONCLUSIONS

Surgically treated pediatric PCs appear to behave as a progressive disease, which starts with cyst diameters of approximately 15 mm and develops with acute or progressive hydrocephalus at the final stage. PC microneurosurgery appears to be associated with a more complete surgical resection compared to other procedures.

Melatonin in Synaptic Impairments of Alzheimer's Disease

Alzheimer's disease (AD) underlies dementia for millions of people worldwide with no effective treatment. The dementia of AD is thought stem from the impairments of the synapses because of their critical roles in cognition. Melatonin is a neurohormone mainly released by the pineal gland in a circadian manner and it regulates brain functions in various manners. It is reported that both the melatonin deficit and synaptic impairments are present in the very early stage of AD and strongly contribute to the progress of AD. In the mammalian brains, the effects of melatonin are mainly relayed by two of its receptors, melatonin receptor type 1a (MT1) and 1b (MT2). To have a clear idea on the roles of melatonin in synaptic impairments of AD, this review discussed the actions of melatonin and its receptors in the stabilization of synapses, modulation of long-term potentiation, as well as their contributions in the transmissions of glutamatergic, GABAergic and dopaminergic synapses, which are the three main types of synapses relevant to the synaptic strength. The synaptic protective roles of melatonin in AD treatment were also summarized. Regarding its protective roles against amyloid-β neurotoxicity, tau hyperphosphorylation, oxygenation, inflammation as well as synaptic dysfunctions, melatonin may be an ideal therapeutic agent against AD at early stage.

Nuclear CRX and FOXJ1 Expression Differentiates Non-Germ Cell Pineal Region Tumors and Supports the Ependymal Differentiation of Papillary Tumor of the Pineal Region

Papillary tumor of the pineal region (PTPR) is a neuroepithelial neoplasm first described in 2003. Despite the anatomic association of PTPR with the pineal gland, the features of these tumors resemble those of the ependymal circumventricular subcommissural organ (SCO) of the posterior third ventricle. Given the presumed distinct derivation of PTPR and pineal parenchymal tumors, we hypothesized that expression of lineage-specific transcription factors could distinguish these tumors and provide additional insight into the differentiation of PTPR. A broad series of pineal region samples was reviewed, including 7 benign pineal glands, 4 pineal cysts, 13 pineocytomas, 28 pineal parenchymal tumors of intermediate differentiation, 11 pineoblastomas, and 18 PTPR. All samples were evaluated by immunohistochemistry for expression of CRX, a master transcriptional regulator of photoreceptor differentiation expressed in pineal gland and retina and/or FOXJ1, a master transcriptional regulator of ciliogenesis expressed in normal ependymal cells and ependymal neoplasms. Diffuse nuclear CRX expression is present in 100% of pineal samples. FOXJ1 is negative in all pineal samples. CRX staining is present in 53% of PTPR, though expression is nearly always limited to rare cells. Diffuse nuclear FOXJ1 expression is present in 100% of PTPR. Fetal human SCO diffusely expressed FOXJ1 but was negative for CRX. Immunohistochemistry for FOXJ1 and CRX differentiates non-germ cell pineal region tumors with high sensitivity and specificity, including pineal parenchymal tumors and PTPR. Our findings support the hypothesis that PTPR have ependymal differentiation and are phenotypically more similar to SCO than pineal gland.

Histopathologic review of pineal parenchymal tumors identifies novel morphologic subtypes and prognostic factors for outcome

BACKGROUND

Pineal parenchymal tumors (PPTs) are rare neoplasms of the central nervous system, and data concerning clinical outcomes are limited. The purpose of this study was to define the clinical behavior of PPT according to current histopathologic criteria and identify prognostic factors to guide therapeutic decisions.

METHODS

Seventy-five patients treated for PPT at a single institution between 1992 and 2015 were retrospectively identified. Forty-five resection specimens were available and re-reviewed. Freedom from progression (FFP) and overall survival (OS) were estimated using the Kaplan-Meier method and compared using log-rank tests.

RESULTS

Median follow-up was 4.1 years. All patients initially underwent surgery; 78% of patients with PPT of intermediate differentiation (PPTID) and all patients with pineoblastoma received adjuvant therapy. Pathologic re-review refined classification in 27% of cases, with the majority of these being adult patients with pineal tumors originally classified as pineoblastomas that more accurately resembled PPTID based on the 2007 WHO classification.

CLASSIFICATION

Our histologic review also identified that PPTIDs can be classified into small-cell and large-cell morphologic subtypes, which have distinct clinical outcomes. Tumor grade, extent of resection, and neuraxis spread were prognostic for FFP. PPTID subtype, extent of resection, and neuraxis spread were prognostic for OS. Genetic analysis of a pineoblastoma case identified somatic mutations of DICER1, ARID1A, and KDM5C genes.

CONCLUSIONS

PPTIDs can be classified into 1 of 2 novel morphologic subtypes that are associated with distinct clinical outcomes. Tumor grade, neuraxis spread, and extent of resection also influence outcome for patients with PPT.

Cytologic features of the normal pineal gland on squash preparations

As primary pineal lesions are extremely rare, many surgical pathologists are unfamiliar with normal pineal cytologic features. We describe cytologic features of the normal pineal gland in patients of varying ages and identify common diagnostic pitfalls. We performed a retrospective review of pineal gland biopsies performed at our institution, where approximately 30,000 surgical specimens are accessioned yearly, for the last 23 years. Only two pineal gland biopsies were found. Although both cases were initially diagnosed as low-grade gliomas on frozen section, the final diagnosis was benign pineal tissue based on light microscopy and immunohistochemistry results. Additionally, we performed squash preparations of five normal pineal gland autopsy specimens with Papanicolaou and Diff-Quik® (Dade Behring, Newark, DE) stains. Infant preparations were highly cellular smears composed of numerous, uniform, single cells with indistinct cytoplasm, small round-to-oval nuclei, fine chromatin, and absent nucleoli and calcifications. The vague microfollicular pattern mimicked a pineocytoma and the fine fibrillary background mimicked a glial neoplasm. Young adult smears were similar; however, microcalcifications were present with fewer background single cells. Older patients had much less cellular smears composed of small clusters of cells with fusiform-to-spindle nuclei, a fine chromatin pattern, and indistinct cytoplasmic borders. There were fewer background single cells and more microcalcifications. The cytologic features of the native pineal gland vary with age. Normal pineal tissue can be confused with a pineocytoma or low-grade glioma. Familiarity with normal pineal gland cytological features will help to avoid a potential misdiagnosis.

Pineal parenchymal tumor of intermediate differentiation: Treatment outcomes of five cases

Pineal parenchymal tumor of intermediate differentiation (PPTID) is a rare disease, first classified by the World Health Organization in 2000. The number of available studies on the treatment of PPTID is currrently limited and the optimal management for this disease has not yet been determined. We retrospectively evaluated the treatment outcomes for PPTID at our institute and analyzed the roles of radiation therapy and chemotherapy for this disease. The clinical data on five patients diagnosed with PPTID since 2000 were retrospectively reviewed. Patients with cerebrospinal dissemination at diagnosis received biopsy-only surgery, craniospinal and whole-ventricular irradiation and chemotherapy. Patients with locally limited disease at diagnosis received local or whole-ventricular irradiation after surgery. The median relapse-free and overall survival were 72.9 and 94.1 months, respectively. Two of the five patients developed a relapse of cerebrospinal dissemination after treatment and succumbed to the disease. All the patients who received both craniospinal and whole-ventricular irradiation exhibited evidence of cerebral white matter abnormalities in magnetic resonance imaging and developed neurocognitive disorders after treatment. Although PPTID may be aggressive and has cerebrospinal fluid seeding potential, PPTID patients may survive long-term, even after recurrence. Considering the long survival time and the late adverse effects due to intensive treatment, the irradiation field and usage of chemotherapy after surgery require optimization.

Pineal tumors

Pineal tumors are a rare and heterogeneous group of primary central nervous system neoplasms, including pineal parenchymal tumors (pineocytomas, pineal parenchymal tumors of intermediate differentiation, and pineoblastomas), germ cell tumors, and neuroepithelial tumors, such as astrocytomas, ependymomas, and papillary tumor of the pineal region. Their classification has evolved over time, with several updates incorporated into the most recent World Health Organization classification, published in 2007. This review highlights the most recent classification and grading scheme for pineal parenchymal tumors and discusses the newly recognized papillary tumor of the pineal region, including clinicopathologic features, differential diagnosis, and management options.

Histopathology of tumors of the pineal region

Pineal region tumors are heterogeneous lesions and include mainly pineal parenchymal tumors (PPTs), papillary tumors of the pineal region (PTPRs) and germ cell tumors (GCTs). This article describes the cystic pineal gland compared with normal tissue and histopathological features of the most frequent pineal region tumors. PPTs are subdivided into pineocytoma (grade I), pineoblastoma (grade IV) and tumors with intermediate differentiation (PPTIDs; grades II-III). A grading system based on the number of mitoses and neurofilament protein expression distinguishes low- from high-grade PPTID. PTPR is a new tumoral entity thought to originate from the subcommissural organ. GCTs include germinoma, embryonal carcinoma, teratoma, yolk sac tumor and choriocarcinoma and are often of mixed histologic composition. New histogenetic data for GCTs are presented.

Pineal parenchymal tumor of intermediate differentiation with papillary features: a continuum of primary pineal tumors?

Pineal parenchymal tumors comprise a rare group of primary neoplasms of the pineal gland. We describe a case involving a 29-year-old woman who presented with signs and symptoms of hydrocephalus secondary to a pineal region tumor obstructing the third ventricle. Surgical resection was performed and pathological analysis revealed a novel diagnosis consistent with a pineal parenchymal tumor of intermediate differentiation (PPTID) with transition to a papillary tumor of the pineal region (PTPR). To our knowledge, this particular pineal region tumor pathology has not yet been reported in the literature and highlights the continuum with which primary pineal tumors exist. We provide a review of the existing literature on pineal region tumors, specifically PTPR and PPTID, and offer insight into the management of these rare neoplasms.

Pineal parenchymal tumors. Management with interstitial iodine-125 radiosurgery

PURPOSE

To evaluate the efficacy of interstitial radiosurgery (IRS) for pineal parenchymal tumors (PPTs).

PATIENTS AND METHODS

18 consecutively admitted patients (twelve male and six female, age range 6-68 years, median age 34 years) with PPTs (eight pineocytomas, ten malignant PPTs) were treated at the authors' institution with IRS using stereotactically guided iodine-125 seed implantation ((125)I-IRS) as either primary or salvage therapy. The cumulative tumor surface dose ranged from 40 to 64 Gy. Adjuvant radiotherapy of the whole brain or the craniospine was done in patients with grade III and grade IV PPT. The median follow-up period was 57.4 months (range 6-134 months).

RESULTS

Overall actuarial 5- and 8-year survival rates after IRS were 100% and 86% for pineocytomas, and the overall actuarial 5-year survival rate was 78% for high-grade PPTs. Follow-up magnetic resonance imaging showed complete remission in 72% (13/18) and partial remission in 28% (5/18) of the cases. One patient developed an out-of-field relapse 4 years after partial remission of a pineocytoma, which had already been treated with IRS. There was no treatment-related mortality. Treatment-related morbidity occurred in two patients only.

CONCLUSION

This study indicates that stereotactic (125)I-IRS for the management of PPTs is quite efficient and safe. Due to the low rate of side effects, IRS may develop into an attractive alternative to microsurgery in de novo diagnosed pineocytomas. In malignant PPTs, IRS may be routinely applied in a multimodality treatment schedule supplementary to conventional irradiation.

CRX is a diagnostic marker of retinal and pineal lineage tumors

Background

CRX is a homeobox transcription factor whose expression and function is critical to maintain retinal and pineal lineage cells and their progenitors. To determine the biologic and diagnostic potential of CRX in human tumors of the retina and pineal, we examined its expression in multiple settings.

Methodology/Principal Findings

Using situ hybridization and immunohistochemistry we show that Crx RNA and protein expression are exquisitely lineage restricted to retinal and pineal cells during normal mouse and human development. Gene expression profiling analysis of a wide range of human cancers and cancer cell lines also supports that CRX RNA is highly lineage restricted in cancer. Immunohistochemical analysis of 22 retinoblastomas and 13 pineal parenchymal tumors demonstrated strong expression of CRX in over 95% of these tumors. Importantly, CRX was not detected in the majority of tumors considered in the differential diagnosis of pineal region tumors (n = 78). The notable exception was medulloblastoma, 40% of which exhibited CRX expression in a heterogeneous pattern readily distinguished from that seen in retino-pineal tumors.

Conclusions/Significance

These findings describe new potential roles for CRX in human cancers and highlight the general utility of lineage restricted transcription factors in cancer biology. They also identify CRX as a sensitive and specific clinical marker and a potential lineage dependent therapeutic target in retinoblastoma and pineoblastoma.

A potential role for crystallization inhibitors in treatment of Alzheimer's disease

Melatonin is a hormone synthesized from the neurotransmitter serotonin and is found mainly in the pineal gland. Melatonin has been suggested to have several properties, acting both as an antioxidant and a neuroprotective agent. Melatonin synthesis decreases with age in all humans, but this decline is more pronounced in Alzheimer's patients. In fact, melatonin inhibits the formation of beta-amyloid protein. The mechanism responsible for this decline has not been fully elucidated, although it is known that the human pineal gland calcifies with age. Such calcification necessarily implies the existence of a tissue injury that, if not reabsorbed by the immune system, will act as heterogeneous nucleant for hydroxyapatite and will induce calcification. For this reason, it is hypothesized that a lack of inhibitors of calcium salt crystallization, such as pyrophosphate and phytate, will favor calcification. Therefore, the absence of crystallization inhibitors may be a risk factor for development of Alzheimer's disease, and this hypothesis should be evaluated.

Pineocytoma and pineal parenchymal tumors of intermediate differentiation presenting cytologic pleomorphism: a multicenter study

Cytologic pleomorphism has been described in a limited number of benign pineal tumors, namely pineocytoma (PC) and pineal parenchymal tumors (PPTs) of intermediate differentiation (PPTID). We examined the clinicopathologic features in a retrospective series of 14 cases (seven females and seven males aged from 10 to 65 years) of pleomorphic PPT. Seven cases were PC, with no mitoses and with areas of tumoral cells forming large pineocytomatous rosettes and other areas with giant cells containing hyperchromatic nuclei. The other seven were PPTID, presenting few mitoses (< or =2), a Ki67 proliferation index between 3% and 7%, and predominantly composed of small neoplastic cells and scattered giant cells, sometimes multinucleated. In the 14 tumors, the proportion of pleomorphic areas was variable. Most tumoral cells showed extensive neuronal differentiation with strong expression of neuron-specific enolase, synaptophysin and neurofilaments. Some of the neoplastic cells expressed S100 protein. The follow-up period ranged from 1.2 to 13 years and only one PC and one PPTID progressed after stereotactic biopsy or incomplete resection. The lack of invasiveness and the low proliferation index of these tumors suggest a benign clinical course despite the marked pleomorphism, the latter of which can lead to upgrading.

Pineal calcification in Alzheimer's disease: an in vivo study using computed tomography

Melatonin has been postulated to have diverse properties, acting as an antioxidant, a neuroprotector, or a stabilizer within the circadian timing system, and is thus thought to be involved in the aging process and Alzheimer's disease (AD). We used computed tomography to determine the degree of pineal calcification (DOC), an intra-individual melatonin deficit marker, as well as the size of uncalcified pineal tissue, in 279 consecutive memory clinic outpatients (AD: 155; other dementia: 25; mild cognitive impairment: 33; depression: 66) and 37 age-matched controls. The size of uncalcified pineal tissue in patients with AD (mean 0.15 cm(2) [S.D. 0.24]) was significantly smaller than in patients with other types of dementia (0.26 [0.34]; P=0.038), with depression (0.28 [0.34]; P=0.005), or in controls (0.25 [0.31]; P=0.027). Additionally, the DOC in patients with AD (mean 76.2% [S.D. 26.6]) was significantly higher than in patients with other types of dementia (63.7 [34.7]; P=0.042), with depression (60.5 [33.8]; P=0.001), or in controls (64.5 [30.6]; P=0.021). These two findings may reflect two different aspects of melatonin in AD. On the one hand, the absolute amount of melatonin excretion capability, as indicated by uncalcified pineal volume, refers to the antioxidant properties of melatonin. On the other hand, the relative reduction in melatonin production capability in the individual, as indicated by DOC, refers to the circadian properties of melatonin.

Prognosis and Histopathologic Features in Papillary Tumors of the Pineal Region

Papillary tumor of the pineal region (PTPR) is a recently described tumor entity thought to arise from the specialized ependyma of the subcommissural organ. Whereas histologic features of PTPR are well defined, data on the prognostic value of PTPR remain scarce. We therefore investigated clinicopathologic features, including data on progression-free survival and overall survival, in a retrospective series of 31 PTPR. The age of the 14 males and 17 females ranged from 5 to 66 years (median age, 29 years). Histologically, all tumors were characterized by an epithelial-like growth pattern in which the vessels were covered by layers of columnar or cuboidal tumor cells forming perivascular pseudorosettes. Most of the tumor cells showed strong expression of neuron-specific enolase, cytokeratins (particularly CK18), S-100 protein, and vimentin. Most PTPRs examined also expressed microtubule-associated protein-2. Expression of synaptophysin, epithelial membrane antigen, transthyretin, neural cell adhesion molecule, and nestin was encountered in some tumors. Gross total resection could be achieved in 21 of 31 cases; 15 patients received radiotherapy on resection of the primary tumor. Nevertheless, the majority of patients experienced recurrences; 5-year estimates for overall survival and progression-free survival were 73% and 27%, respectively. To conclude, the clinical course of PTPR is characterized by frequent local recurrence, and the value of radiotherapy on disease progression will need to be investigated in future prospective trials.

Postoperative adjuvant treatment for pineal parenchymal tumour of intermediate differentiation

Pineal parenchymal tumour of intermediate differentiation (PPTID) in adults is rare and a treatment strategy for this condition has not yet been established. We present a case of an elderly patient treated with postoperative adjuvant therapy using radio- and chemotherapy. This 60-year-old man presented with a 3-month history of memory disturbance, gait instability and double vision. Computed tomography and magnetic resonance imaging demonstrated a mass in the pineal region that suggested a malignant tumour. Partial removal of the tumour was undertaken via the right occipital transtentorial approach. The histological diagnosis was PPTID. Postoperative radio- and chemotherapy were administered, with a good response. Little is known about the clinical behaviour of PPTID in adults. Our treatment plan indicates one effective option for the management of such tumours.

Microarray Analysis Reveals Differential Gene Expression Patterns in Tumors of the Pineal Region

Several types of tumors are known to originate from the pineal region, among them pineal parenchymal tumors (PPTs) and papillary tumors of the pineal region (PTPRs), probably derived from the subcommissural organ. As a result of their rarity, their histologic diagnosis remains difficult. To identify molecular markers, using CodeLink oligonucleotide arrays, gene expression was studied in 3 PPTs (2 pineocytomas and one pineoblastoma), 2 PTPRs, and one chordoid glioma, another rare tumor of the third ventricle. Because PTPR and chordoid glioma may present ependymal differentiation, gene expression was also analyzed in 4 ependymomas. The gene patterns of the 3 PPTs fell in the same cluster. The pineocytomas showed high expression of TPH, HIOMT, and genes related to phototransduction in the retina (OPN4, RGS16, and CRB3), whereas the pineoblastoma showed high expression of UBEC2, SOX4, TERT, TEP1, PRAME, CD24, POU4F2, and HOXD13. Using reverse transcriptase-polymerase chain reaction on 13 PPTs, we demonstrated that PRAME, CD24, POU4F2, and HOXD13 might be candidates for grading PPT with intermediate differentiation. PTPRs, classified with chordoid glioma and separately from ependymomas, showed high expression of SPEDF, KRT18, and genes encoding proteins reported to be expressed in the subcommissural organ, namely ZFH4, RFX3, TTR, and CGRP. Our results highlight the usefulness of gene expression profiling for classify tumors of the pineal region and identify genes with potential use as diagnostic markers.

Pineal parenchymal tumors: a correlation of histological features with prognosis in 66 cases

The WHO classification of CNS tumors divides pineal parenchymal tumors (PPT) into pineocytoma (PC), pineoblastoma (PB) and mixed pineocytoma-pineoblastoma or PPT with intermediate differentiation. The reported incidence of mixed/intermediate PPT varies and this may reflect the difficulty in classifying tumors of this type. In an attempt to overcome the problem of the classification of PPT with intermediate differentiation, we describe the relationship between histological features and patient survival in a large cooperative series of 66 PPT from 12 neurosurgical centres. All tumors were studied with both light microscopy and immunohistochemically using antibodies against glial markers or neural/neuroendocrine markers. Our series included 11 PC, 39 mixed/intermediate PPT and 16 PB. A number of mitoses greater than 6 and the presence of necrosis were associated with a poorer outcome, while positive immunostaining for neurofilaments was associated with a better survival. We propose a new prognostic grading of 4 grades, grade I for PC, grade II for PPT with fewer than 6 mitoses and positive immunolabelling for neurofilaments, grade III for PPT with either 6 or more than 6 mitoses or fewer than 6 mitoses but without immunostaining for neurofilaments and grade IV for PB.

The role of Gamma Knife radiosurgery in the treatment of pineal parenchymal tumours

OBJECT

The aim of this study was to document the possible role of Gamma Knife radiosurgery, suitable for the treatment of deep and well limited tumors, in the management of pineal parenchymal tumors (PPT).

POPULATION AND METHODS

We reviewed retrospectively a series of 13 patients with PPT treated by Gamma Knife radiosurgery during 16 procedures. Mean age was 31 (range 10 to 74). Eight patients had pineocytomas (61.5%), and 5 had pineoblastomas (38.5%). Radiosurgery was performed alone in 6 cases, after partial microsurgical resection in 3 cases, in association with chemotherapy in 3 cases and following conventional fractionated radiotherapy in 1 case. The marginal dose to these tumors ranged from 11 to 20 Gy (mean 15 Gy).

RESULTS

With a mean follow-up of 34 months (range 6 to 88), all tumors responded to treatment and disappeared or ceased growing. Two patients with pineoblastoma had tumor size progression out of the initial target requiring several radiosurgery procedures. At the end of the follow-up period, 10 out of 12 patients were alive. Two patients with pineoblastoma died because of carcinomatous meningitis or tumor size progression. We observed no mortality or major morbidity related to radiosurgery.

CONCLUSION

This study confirms that radiosurgery can be an effective and safe primary treatment modality for patients with pineocytomas. It should have a role in multimodality therapy which includes microsurgical resection, fractionated radiotherapy and chemotherapy for the management of malignant pineal tumors.

Identification of differentially expressed genes in human pineal parenchymal tumors by microarray analysis

Human pineal parenchymal tumors (PPTs) are rare tumors, and little is known about their molecular pathogenesis. We used Atlas plastic human 8 K microarray analysis to identify the genes expressed in four human PPTs of different grades, in normal brain tissue and in a normal fetal pineal gland. We selected the most highly expressed genes in PPT (n=39) and compared their expression to that both in normal brain and fetal pineal gland. Nine genes were expressed more than twice as strongly and 3 at about half the level in PPT. Furthermore, real-time reverse transcription-PCR was performed to compare mRNA levels in the four PPTs, in four medulloblastomas (MBs) (the most common type of similar embryonal neoplasm in the cerebellum), and in normal brain, for 9 of the 39 genes. Among genes showing an expression similar to that obtained with microarray, puromycin-sensitive aminopeptidase and teratocarcinoma-derived growth factor 3 were up-regulated in PPT and in MB, and adenomatous polyposis coli like was down-regulated only in PPT. Up-regulated expression of chromosome 17 open reading frame 1A was seen in high-grade PPT and in MB, but not in lower grade PPT. In conclusion, our results identified a number of genes that are differentially expressed in PPT and MB, and some of them may serve as prognostic markers and can be used to define mechanisms of tumorigenesis.

Papillary neuroepithelial tumor of the pineal region. A case report

We present here an unusual case of papillary neuroepithelial tumor of the pineal region. The patient was a 29-year-old female who presented with headaches. A computed tomography scan revealed a tumorous lesion at the pineal region and hydrocephalus. The resected tumor was composed of columnar and cuboidal cells showing characteristics of papillary growth. The tumor cells exhibited diffuse and intense immunoreactivity to cytokeratins and neural cell adhesion molecule. The tumor expressed abundant levels of transthyretin (prealbumin) and appeared ependymal in nature, with numerous microlumens delineated by punctate and ring-like patterns in epithelial membrane antigen staining. Reactivity to synaptophysin and glial fibrillary acidic protein was observed only in the infiltrated non-neoplastic pineal parenchyma. These histological characteristics matched the description of the recently reported papillary tumor of the pineal region thought to originate from the specialized ependyma of the subcommissural organ (SCO). Transthyretin expression of the present case further supports the likelihood of SCO origin, as transthyretin is one of the proteins presumed to be secreted by human SCO.

Papillary tumor of the pineal region

Primary papillary tumors of the central nervous system are rare. We have encountered a series of six papillary tumors of the pineal region with distinctive features that appear to represent a clinicopathologic entity. The tumors occurred in four women and two men, ranging in age from 19 to 53 years. Imaging studies showed a large well-circumscribed mass in the pineal region. The tumors were characterized by an epithelial-like growth pattern, in which the vessels were covered by a layer of tumoral cells. In papillary areas, the neoplastic cells were large, columnar or cuboidal, with a clear cytoplasm. Nuclei, round or infolded, were found generally at the basal pole of tumoral cells. Immunohistochemically, the tumor cells showed strong staining for cytokeratin, S-100 protein, neuron-specific enolase, and vimentin but only weak or no staining for epithelial membrane antigen and glial fibrillary acid protein. Ultrastructural examination of two cases revealed abundant rough endoplasmic reticulum with distended cisternae filled with secretory product, microvilli, and perinuclear intermediate filaments. The morphofunctional features of these papillary tumors of the pineal region, remarkably uniform within this series, are similar to those described for ependymal cells of the subcommissural organ, and the papillary tumors of the pineal region may be derived from these specialized ependymocytes.

Pineal parenchymal tumor with marked retinoblastic differentiation: Case report

A 53-year-old woman was found to have a tumor in the pineal region. Histologically, Homer-Wright rosettes were sporadically distributed in a diffuse proliferation of round tumor cells that were immunoreactive for synaptophysin and chromogranin. A few perivascular pseudorosettes were also present, and the perivascular tumor cells were immunoreactive for glial fibrillary acidic protein and vimentin. By electron microscopy, well-developed junctions and pronounced interdigitation of abutting plasma membranes were noted in many tumor cells, as well as abundant intracytoplasmic microtubules. These findings indicated that the tumor was a pineal parenchymal tumor accompanied by an extraordinary epithelial-like differentiation, suggesting retinoblastic photoreceptor cell differentiation.

Differential somatostatin receptor subtype expression in human normal pineal gland and pineal parenchymal tumors

Somatostatin is a potent antiproliferative signal in both tumoral and normal mammalian cells, and altered somatostatin receptor (sst) expression is associated with carcinogenesis in human tissues. In this study, two normal and three tumoral human pineal glands were analyzed using the reverse transcriptase-polymerase chain reaction (RT-PCR) for the presence of mRNA coding for the five different somatostatin receptors (sst1-sst5). Pineal parenchymal tumor (PPT) differentiation was confirmed by immunohistochemical detection of neuroendocrine markers (synaptophysin, neurofilaments, and chromogranin A). The presence of mRNA coding for c-myc, a proto-oncogene, and for tryptophan hydroxylase (TPOH), serotonin N-acetyltransferase (NAT), and hydroxyindole-O-methyltransferase (HIOMT), enzymes of the melatonin pathway, was also analyzed by RT-PCR. Only the tumoral tissues contained c-myc mRNA. All five tissues contained TPOH, NAT, and HIOMT mRNA, the levels of HIOMT mRNA being lower in PPT than in the normal pineal gland, suggesting that PPT retain the ability to synthesize melatonin. All tissues contained sst1, sst2, and sst3 transcripts, but not sst4, while small amounts of sst5 mRNA were only found in normal pineal glands. Real-time PCR, performed only with the most abundant subtpe sst2, evidenced an about sixfold higher level in in normal pineal glands. These results demonstrate the presence of somatostatin receptors in the human pineal gland, as described in other species, and point to a differential expression of the sst2 and sst5 subtypes associated with carcinogenesis.

Malignant pineal parenchymal tumors in adult patients: patterns of care and prognostic factors

OBJECTIVE

The aim of our study was to analyze patterns of care and to identify prognostic factors in patients at least 18 years of age who received radiotherapy for malignant pineal parenchymal tumors.

METHODS

In a multicenter, retrospective study, we analyzed data for 37 previously published cases and 64 patients treated at the participating institutions.

RESULTS

A total of 56 patients received postoperative radiotherapy, and 45 patients received primary radiotherapy. Chemotherapy was administered to 34 patients. The median follow-up period was 38 months, and median overall survival was 100 months. The variables that significantly influenced overall survival were the extent of disease (localized versus disseminated; P = 0.0002), differentiation (pineal parenchymal tumor of intermediate differentiation versus pineoblastoma; P = 0.001), and residual disease (> or = 50% versus < 50% reduction in size; P < 0.0001). In a multivariate analysis, the parameters turned out to be independent risk factors. The median survival in patients with local or spinal failure was 15 months. Local control was better in older patients (> or = 32 yr versus < 32 yr; P = 0.02). Spinal control was more successful in patients with pineal parenchymal tumors of intermediate differentiation than it was in patients with pineoblastomas (P = 0.03). Nine of 45 treatment failures occurred later than 5 years after treatment.

CONCLUSION

Stage, histological characteristics, and response are independent risk factors in adults with malignant pineal parenchymal tumors. Late relapses are common.

Pathology of pineal region tumors

Various histological types of tumors arise in the pineal region. The most common tumors are pineal parenchymal tumors and germ cell tumors. Pineal parenchymal tumors are divided into pineocytoma, pineal parenchymal tumor with intermediate differentiation and pineoblastoma. Pineocytomas are well-differentiated tumors and retain the morphological and immunohistochemical features of pineal parenchymal cells. Lobular architectures and pineocytomatous rosettes are also typical features. In contrast, pineoblastomas are embryonal tumors resembling primitive neuroectodermal tumors (PNET). However, pineoblastomas are distinct from PNET in other sites due to their exhibiting photosensory differentiation including Flexner-Wintersteiner rosettes and fleurettes. Although pineal cysts are tumor-like lesions, and not true neoplasms, they are occasionally difficult to distinguish from pineocytoma and astrocytoma. From the therapeutic aspect, a precise differential diagnosis is critical. The pineal region is the most common site of the brain in which germ cell tumors occur. Germinoma, teratoma, embryonal carcinoma, yolk sac tumor and choriocarcinoma are encountered, and the latter three types of tumors usually constitute elements of mixed germ cell tumors. The morphological and immunohistochemical features of intracranial germ cell tumors are very similar to those of gonadal germ cell tumors, although there are some differences in germinoma. Pineal germinoma may exhibit carcinomatous differentiation. Other types of tumors are occasionally observed, including fibrillary and pilocytic astrocytoma, glioblastoma, ependymoma, melanoma, meningioma and so on. Metastatic pineal tumors are also rare. The most common site of origin for pineal metastasis is the lung.

Vertebral metastases from pineoblastoma

Two male patients aged 26 and 18 years presented with vertebral metastases originating from pineoblastomas on which surgery had been performed 8 years and 5 months earlier, respectively. In the first case in which the metastasis developed in the T8 corpus, the disease is presently under control after high-dose chemotherapy and autologous blood stem cell transplantation. The second patient (sacral metastasis), despite aggressive adjuvant therapy, died 2 years after the last operation because of spinal seeding. These uncommon cases are discussed with reference to the literature on extraneural metastases that originate from neuroepithelial tumors of the central nervous system.

Comparative genomic hybridization in pineal parenchymal tumors

Nine pineal parenchymal tumors were studied by comparative genomic hybridization. These consisted of three pineocytomas (WHO grade II), three pineal parenchymal tumors of intermediate differentiation (WHO grade III), and three pineoblastomas (WHO grade IV). An average of 0 chromosomal changes per pineocytoma, 5.3 per pineal parenchymal tumor of intermediate differentiation (3.3 gains vs. 2.0 losses), and 5.6 per pineoblastoma (2.3 gains vs. 3.3 losses) were found. The most frequent DNA copy number changes among pineal parenchymal tumors of intermediate differentiation and pineoblastomas were gains of 12q (3/6 cases), 4q, 5p, and 5q (2/6 cases each), as well as losses of 22 (4/6 cases), 9q, and 16q (2/6 cases each). Among pineal parenchymal tumors of intermediate differentiation, the most common chromosomal imbalances were +4q, +12q, and -22 (2/3 cases each), and in pineoblastomas -22 (2/3 cases). Five high level gains were identified, all of them in pineoblastomas; these were found on 1q12-qter, 5p13.2-14, 5q21-qter, 6p12-pter, and 14q21-qter. Clinically, all patients with pineocytomas and pineal parenchymal tumors of intermediate differentiation were alive after a mean observation time of 142 and 55 months, respectively, whereas all patients with pineoblastomas had died after an average of 17 months. Our findings suggest that pineal parenchymal tumors of intermediate differentiation are cytogenetically more similar to pineoblastomas and prognostically more similar to pineocytomas. Furthermore, imbalances in higher-grade pineal parenchymal tumors mainly affect gains of 12q and losses of chromosome 22.

Clinicopathological study of pineal parenchymal tumors: correlation between histopathological features, proliferative potential, and prognosis

This study describes the clinicopathologic features of 13 cases with pineal parenchymal tumors. Based on the histopathologic findings, especially the extent of atypia and pineocytic differentiation as determined by Bodian's staining, we classified these tumors into pineocytomas (4), pineocytomas with anaplasia (4) and pineoblastomas (5). All the cases with pineocytoma and pineocytoma with anaplasia were adults, and all the cases with pineoblastoma were younger children. One patient with pineocytoma died of other disease 7 months after initial treatment. One patient with pineocytoma with anaplasia died 168 months after initial treatment. The other patients with pineocytoma and pineocytoma with anaplasia survived between 9 and 179 months after surgery. However, all of the five pineoblastoma patients died within 14 months after initial treatment. The mean MIB-1 index in pineoblastomas was significantly higher than that in other types of pineal parenchymal tumors, but there were no differences between pineocytomas and pineocytomas with anaplasia with respect to the MIB-1 index. The mean MIB-1 index in neurofilament protein-immunopositive cases was significantly lower than that in immunonegative cases. With regard to the malignant potential, we emphasize that a clear distinction should be made between pineoblastomas in children and other types of pineal parenchymal tumors in adults.

Cytogenetic and ultrastructural study of a pineocytoma case report

The authors report a case of pineocytoma in a 44-year-old woman suffering from headache, vomiting and Parinaud syndrome. At histopathological examination the neoplasm showed a ill-defined lobulate pattern with some small pineocytomatous rosettes. The electron-microscopy revealed cells of moderate size and oval nuclei with smooth nuclear envelopes; well-developed organelles were found in the, abundant cytoplasm. The chromosome analysis revealed this kariotype: 58-59, XXX, -4, -5, -13, - 14, -15, + 19. This is the first report of a pineocytoma with ultrastructural and cytogenetic study; it confirms the literature findings of the electron-microscopy, whereas there is partial accordance with the previous cytogenetic studies.

Parenchymal pineal tumors: a clinicopathological study of 76 cases

PURPOSE

The aim of this study was to identify factors that could lead to optimization of the management of pineal parenchymal tumors (PPT) which remains equivocal and controversial.

METHODS AND MATERIALS

In order to determine factors that influence PPT prognosis, a series of 76 consecutive patients from 12 European centers with histologically proven tumors was retrospectively reviewed. The clinical records and material for histologic review were available in all cases. Follow-up was achieved in 90% of cases.

RESULTS

According to WHO classification, there were 19 pineocytomas, 28 intermediate and mixed PPT, and 29 pineoblastomas. According to a four-grade institutional classification, there were 11 Grade 1, 27 Grade 2, 20 Grade 3, and 18 Grade 4. Surgical resection was attempted in 44 patients, whereas 30 had biopsy only. In one case, diagnosis was made at autopsy and in another on spinal deposits. Forty-four patients were irradiated following surgery, 15 patients received chemotherapy. Forty-one patients were alive (median follow-up: 85 months); 9 patients died perioperatively; 26 patients relapsed. Univariate analysis showed a good outcome correlated with age above 20 years, tumor diameter less than 25 mm, and low-grade histology. Multivariate analysis confirmed histology and tumor volume to be significant independent prognostic factors. The extent of surgery and radiotherapy had no clear influence on survival.

CONCLUSIONS

This review highlights the prognostic features of PPT and may help to determine treatment strategies based on radiologic and pathologic characteristics.

Synaptic-like microvesicles in mammalian pinealocytes

The recent deciphering of the protein composition of the synaptic vesicle membrane has led to the unexpected identification of a compartment of electron-lucent microvesicles in neuroendocrine cells which resemble neuronal synaptic vesicles in terms of molecular structure and function. These vesicles are generally referred to as synaptic-like microvesicles (SLMVs) and have been most intensively studied in pancreatic beta-cells, chromaffin cells of the adrenal medulla, and pinealocytes of the pineal gland. This chapter focuses on the present knowledge of SLMVs as now well-established constituents of mammalian pinealocytes. I review the results of morphological, immunocytochemical, and biochemical studies that were important for the characterization of this novel population of secretory vesicles in the pineal organ. The emerging concept that SLMVs serve as a device for intercellular communication within the pineal gland is outlined, and unanswered questions such as those pertaining to the physiological function and regulation of pineal SLMVs are discussed.