Topographical distribution and prevalence of basal duct-like recess sign in a cohort of Papillary Craniopharyngioma-novel findings and implications

PURPOSE

Basal duct-like recess (DR) sign serves as a specific marker of papillary craniopharyngiomas (PCPs) of the strictly third-ventricular (3 V) topography. Origins of this sign are poorly understood with limited validation in external cohorts.

METHODS

In this retrospective study, MRIs of pathologically proven PCPs were reviewed and evaluated for tumor topography, DR sign prevalence, and morphological subtypes.

RESULTS

Twenty-three cases with 24 MRIs satisfied our inclusion criteria. Median age was 44.5 years with a predominant male distribution (M/F ratio 4.7:1). Overall, strictly 3 V was the commonest tumor topography (8/24, 33.3%), and tumors were most commonly solid-cystic (10/24, 41.7%). The prevalence of DR sign was 21.7% (5/23 cases), all with strictly 3 V topography and with a predominantly solid consistency. The sensitivity, specificity and positive and negative predictive value of the DR sign for strict 3 V topography was 62.5%, 100%, 100% and 84.2% respectively. New pertinent findings associated with the DR sign were observed in our cohort. This included development of the cleft-like variant of DR sign after a 9-year follow-up initially absent at baseline imaging. Additionally, cystic dilatation of the basal tumor cleft at the pituitary stalk-tumor junction and presence of a vascular structure overlapping the DR sign were noted. Relevant mechanisms, hypotheses, and implications were explored.

CONCLUSION

We confirm the DR sign as a highly specific marker of the strictly 3 V topography in PCPs. While embryological and molecular factors remain pertinent in understanding origins of the DR sign, non-embryological mechanisms may play a role in development of the cleft-like variant.

Microsurgical Resection of a Parachiasmatic Craniopharyngioma via a Left-Sided Pterional Transsylvian Approach

Craniopharyngiomas are histologically benign tumors that originate from squamous rests along the pituitary stalk. They make up approximately 1.2% to 4.6% of all intracranial tumors and do not show significant differences in occurrence based on sex. Adamantinomatous craniopharyngiomas have 2 peaks of incidence, commonly observed in patients from ages 5 to 15 years and again from 45 to 60 years. In contrast, papillary craniopharyngiomas mainly affect adults in their fifth and sixth decades of life.1 The "malignancy" of craniopharyngiomas is attributed to their location and the challenges associated with achieving complete removal because they can manifest in the sellar, parachiasmatic, and intraventricular regions or a combination of these.2,3 Various approaches have been used to resect these tumors.4,5 Radical resection offers the most promising option for disease control, potential cure, and the ability to transform the disease from lethal to survivable in children, allowing for a functional adult life.2,3 Meticulous evaluation is crucial to determine the appropriate approach and side, with particular emphasis on closely examining the relationship between the tumor and optic pathways (nerve, chiasm, tract), which are frequently involved. This assessment should also include the tumor's relationship with other crucial structures, such as the hypothalamus and adjacent arteries, to ensure that the strategy is adjusted accordingly to further minimize the risk of postoperative morbidity. Video 1 demonstrates a left-sided pterional transsylvian approach to remove a parachiasmatic craniopharyngioma involving the left optic chiasm and tract.

Dabrafenib as a diagnostic and therapeutic strategy for the non-surgical management of papillary craniopharyngioma

PURPOSE

Papillary craniopharyngiomas can cause considerable morbidity due to mass effect and potential surgical complications. These tumors are known to harbor BRAF V600 mutations, which make them exquisitely sensitive to BRAF inhibitors.

METHODS

The patient is a 59 year old man with a progressive suprasellar lesion that was radiographically consistent with a papillary craniopharyngioma. He was consented to an Institution Review Board-approved protocol, which permits sequencing of cell free DNA in plasma and the collection and reporting of clinical data.

RESULTS

The patient declined surgical resection and was empirically treated with dabrafenib at 150 mg twice daily. Treatment response was demonstrated after 19 days, confirming the diagnosis. After achieving a near complete response after 6.5 months on drug, a decision was made to deescalate treatment to dabrafenib 75 mg twice daily with subsequent tumor stability for 2.5 months.

CONCLUSION

Patients with a suspected papillary craniopharyngioma can be challenged with dabrafenib as a potentially effective diagnostic and therapeutic strategy, given that rapid regression with dabrafenib is only observed in tumors harboring a BRAF V600 mutation. Further work is needed to explore the optimal regimen and dose of the targeted therapy.

Diagnosis and Management of Pediatric Papillary Craniopharyngiomas

OBJECTIVE

Papillary craniopharyngioma (PCP) was previously believed to occur only in adults. Sporadic pediatric PCP (PPCP) confirmed by detection of BRAF V600E mutation has been reported since 2018, but is often misdiagnosed before being diagnosed definitively. We aimed to evaluate PPCP characteristics and propose diagnostic criteria for prompt diagnosis, seeking to reduce patient morbidity and mortality and reduce costs linked to misdiagnosis.

METHODS

This study included 5 patients with PPCPs whose data were retrieved retrospectively from among 1032 patients with craniopharyngiomas admitted to Sanbo Brain Hospital Management Group from March 2017 to May 2021. Patients' demographics, clinical presentation, tumor imaging characteristics, histopathologic results, surgical approaches, and postoperative outcomes were analyzed.

RESULTS

PPCP was misdiagnosed intraoperatively as sellar abscess (n = 4) or Rathke cleft cyst (n = 1). Preoperative magnetic resonance imaging showed that all tumors were under the saddle diaphragm, and the cyst wall was enhanced (n = 5). Computed tomography scans showed scattered high-density signs (n = 4). No recurrence was noted after complete resection. Postoperative hypothalamic dysfunction was mild. BRAF V600E mutation was confirmed in all cases by sequencing and immunohistochemistry. Immunohistochemistry showed granulation and inflammation and MPO, CD3, CD20, CD38, CD68, and CD163 were positively expressed.

CONCLUSIONS

Misdiagnosis of PPCP is responsible for failed surgical treatment. We propose that prompt diagnosis of PPCP can be achieved if preoperative magnetic resonance images show the tumor under saddle diaphragm with tumor wall enhancement and computed tomography scans show high-density signs scattered in the tumor, which leads to safe, effective tumor resection. Our proposed diagnosis and treatment strategy for PPCP reduces morbidity and mortality.

Duct-like diverticulum at the base of third ventricle tumors: a morphological signature diagnostic of papillary craniopharyngioma

This study describes and characterizes a narrow, hollow tubular structure, termed as duct-like diverticulum (DV), found specifically at the basal midline of papillary craniopharyngiomas (PCPs) located within the third ventricle (3V). The presence of this structure was systematically investigated on autopsy studies and magnetic resonance imaging (MRI) scans of 3536 craniopharyngioma (CP) cases published in the medical literature from 1911 to 2021, as well as in other twelve 3V tumor categories (n = 1470 cases). A basal DV was observed in a total of 50 PCPs, including two of our own cases. This DV corresponds to a tubular-shaped recess invaginated at the midline bottom of the tumor, following the same angled trajectory as the pituitary stalk. It can be easily seen as a hypointense linear structure on T1- and T2-weighted MRI scans, with two main length types: long DVs (74%), which reach the tumor center, and short DVs (26%), which penetrate the tumor only a few millimeters. The DV sign identifies the papillary CP type with a specificity of 100% and a sensitivity of 33% in the overall CP population. This finding also serves to establish the strictly intra-3V location of the lesion with a 95% specificity and 42% sensitivity among papillary CPs. No similar basal DV was found in adamantinomatous CPs nor among other categories of strictly 3V tumors. Consequently, the presence of a diverticulum in a 3V tumor represents a morphological signature pathognomonic of the papillary type and a valuable sign to reliably define the strictly 3V topography.

Papillary Craniopharyngioma: A Type of Tumor Primarily Impairing the Hypothalamus - A Comprehensive Anatomo-Clinical Characterization of 350 Well-Described Cases

OBJECTIVE

Papillary craniopharyngiomas (PCPs) represent a rare histological type of craniopharyngiomas (CPs) usually involving the hypothalamus. This study systematically analyzes the clinical-anatomical correlation between tumor topography and symptoms related to hypothalamic dysfunction in the largest series of PCPs ever gathered.

METHODS

From 5,346 CP reports published from 1856 to 2021, we selected 350 well-described cases of the squamous-papillary type. Clinical presentation, tumor topography, severity of hypothalamic adhesion, patient outcome, and tumor recurrence were thoroughly analyzed.

RESULTS

PCPs predominantly occur in adult (96.3%), male (61.7%) patients presenting with headache (63.4%), visual alterations (56.2%), and psychiatric disturbances (50.4%). Most PCPs are solid (50%), round (72%) lesions that occupy the third ventricle (3V, 94.8%) and show low-risk severity adhesions to the hypothalamus (66.8%). Two major topographical categories can be found: strictly 3V (57.5%), growing above an intact 3V floor, and not-strictly or infundibulo-tuberal (32.9%), expanding at the infundibulum and/or tuber cinereum. The hypothalamic syndrome predominated among strictly 3V PCPs (p < 0.001). Psychiatric symptoms (p < 0.001) and high-risk hypothalamic attachments (p = 0.031) related to unfavorable postoperative outcomes among patients treated from 2006 onwards. The not-strictly 3V topography was identified as the major predictor of high-risk hypothalamic attachments (71.2% correctly predicted), which, along with incomplete tumor removal (p = 0.018), underlies the higher tumor recurrence of this topography (p = 0.001).

CONCLUSIONS

This systematic review evidences that PCP topography is a major determinant of hypothalamic-related symptoms, type of hypothalamic attachments, and tumor recurrence rate. Accurate preoperative definition of PCP-hypothalamus relationships is essential for the judicious, safe management of these complex lesions.

Biological Behaviour of Craniopharyngiomas

Jakob Erdheim (1874-1937) first described craniopharyn-giomas (CPs) as "hypophyseal duct tumours" and postulated the existence of two tumour types based on their histological features: (1) an aggressive type showing similarities to adamantinomas (tumours of the jaw) and (2) a more benign form characterised by the presence of papillary structures. More than a century later, these initial observations have been confirmed; based on their distinct genetic, epigenetic, and histological features, the WHO classifies CPs into two types: adamantinomatous CPs (ACPs) and papillary CPs (PCPs). Considerable knowledge has been generated on the biology of CPs in the last 20 years. Mutations in CTNNB1 (encoding β-catenin) are prevalent in ACP, whilst PCPs frequently harbour mutations in BRAF (p.BRAF-V600E). The consequence of these mutations is the activation of either the WNT/β-catenin (ACP) or the MAPK/ERK (PCP) pathway. Murine models support a critical role for these mutations in tumour formation and have provided important insights into tumour pathogenesis, mostly in ACP. A critical role for cellular senescence has been uncovered in murine models of ACP with relevance to human tumours. Several gene profiling studies of human and murine ACP tumours have identified potential targetable pathways, and novel therapeutic agents are being used in clinical and pre-clinical research, in some cases with excellent results. In this review, we will present the accumulated knowledge on the biological features of these tumours and summarise how these advances are being translated into potential novel treatments.

MAPK pathway control of stem cell proliferation and differentiation in the embryonic pituitary provides insights into the pathogenesis of papillary craniopharyngioma

Despite the importance of the RAS-RAF-MAPK pathway in normal physiology and disease of numerous organs, its role during pituitary development and tumourigenesis remains largely unknown. Here, we show that the over-activation of the MAPK pathway, through conditional expression of the gain-of-function alleles BrafV600E and KrasG12D in the developing mouse pituitary, results in severe hyperplasia and abnormal morphogenesis of the gland by the end of gestation. Cell-lineage commitment and terminal differentiation are disrupted, leading to a significant reduction in numbers of most of the hormone-producing cells before birth, with the exception of corticotrophs. Of note, Sox2+ stem cells and clonogenic potential are drastically increased in the mutant pituitaries. Finally, we reveal that papillary craniopharyngioma (PCP), a benign human pituitary tumour harbouring BRAF p.V600E also contains Sox2+ cells with sustained proliferative capacity and disrupted pituitary differentiation. Together, our data demonstrate a crucial function of the MAPK pathway in controlling the balance between proliferation and differentiation of Sox2+ cells and suggest that persistent proliferative capacity of Sox2+ cells may underlie the pathogenesis of PCP.

Targeted BRAF and CTNNB1 next-generation sequencing allows proper classification of nonadenomatous lesions of the sellar region in samples with limiting amounts of lesional cells

PURPOSE

To assess the role of high sensitivity next-generation sequencing (NGS) of CTNNB1 for the diagnosis of adamantinomatous craniopharyngiomas (aCPs) and of BRAF for that of papillary CPs (pCPs) in routinely processed surgical samples of non-adenomatous sellar lesions.

METHODS

Forty-five cases of patients operated for non-adenomatous masses of the sellar region between 2004 and 2014 were retrieved from the files of the Anatomic Pathology unit of the Bellaria Hospital in Bologna, Italy. BRAF and CTNNB1 mutation status was analyzed by NGS in samples smaller than 1 cm(3) and histological re-evaluation was performed on all cases.

RESULTS

CTNNB1 mutation analysis showed a sensitivity of 86.7 % and a specificity of 96.2 % for the diagnosis of aCPs. The specificity increased to 100 % considering that in one case, initially classified as a non-CP lesion (xanthogranuloma), the identification of a CTNNB1 S47R lead to histological re-evaluation and reclassification of the lesion as aCP. BRAF mutation analysis had a sensitivity of 76.9 % and a specificity of 96.4 % for the diagnosis of pCPs. The specificity increased to 100 % considering that in one case, initially classified as a Rathke cyst, the identification of BRAF V600E lead to histological re-evaluation and reclassification of the lesion as pCP.

CONCLUSIONS

This study confirms the diagnostic relevance of the molecular alterations recently identified in aCPs and pCPs and shows how the identification of BRAF and CTNNB1 mutations can be instrumental for the proper classification of samples that contain limiting amounts of diagnostic lesional tissue.