Persisting Embryonal Infundibular Recess (PEIR): Two Case Reports and Systematic Literature Review

Endoscopic Endonasal Surgery for Uncommon Pathologies of the Sellar and Parasellar Regions

Endoscopic skull base surgery has become an integral part of the present neurosurgical armamentarium. The pioneering efforts in which the purely endoscopic transsphenoidal approach was introduced have triggered a growing tide of using the endoscopic endonasal procedures for a large variety of skull base lesions. Because of their anatomical peculiarities, lesions of the sellar and parasellar regions lend themselves very well to the endoscopic endonasal approaches. Apart from the common pathological entities, many other less frequent pathologies are encountered in the sellar and parasellar area. In this chapter, we review the surgical technique of the endoscopic endonasal transsphenoidal approach and its extensions applied to a variety of rare and uncommon pathological entities involving the sella turcica and clivus. An overview of these pathological entities is also presented and exemplified.

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.

Persisting embryonal infundibular recess (PEIR) and transsphenoidal-transsellar encephaloceles: distinct entities or constituents of one continuum?

Persisting embryonal infundibular recess (PEIR) is a very rare anomaly of the floor of the third ventricle in which the embryonic morphology of the infundibular recess (IR) persists. The exact underlying mechanism of development of PEIR is unknown, and the anomaly has been reported as an isolated finding or in association with other conditions. On the other hand, trans-sphenoidal encephaloceles are the rarest form of basal encephaloceles. The trans-sphenoidal trans-sellar encephalocele (TSE) is the least common variant in which the pituitary gland, pituitary stalk, optic pathways, parts of the third ventricle and IR may be present within the encephalocele. We recently treated one patient with TSE. Based on the observed morphological similarity of the IR in our patient and in the published cases of PEIR, we reviewed the literature in order to validate the hypothesis that PEIR and TSE may possibly belong to one spectrum of malformations. Across the published reports, the morphology of the IR in TSE is very closely similar to PEIR. Moreover, radiological, patho-anatomical, and embryological evidence is in support to our hypothesis that PEIR and TSE are most likely the two extremes of the same continuum of malformations.

Basal Recess in Third Ventricle Tumors: A Pathological Feature Defining a Clinical-Topographical Subpopulation of Papillary Craniopharyngiomas

This study investigates the presence of a hollow recess at the midline undersurface of tumors primarily localized within the third ventricle (3V). This structure was originally identified by magnetic resonance imaging (MRI) of 6 3V craniopharyngiomas (CPs) from our series and was then methodically scrutinized in autopsy studies (n = 1091) and MRI scans (n = 5558) of CPs and in 1251 3V tumors reported in the medical literature from 1839 to 2021. A recess at the tumor base was identified in 110 CPs, 95 with a verified papillary histology (papillary craniopharyngioma [PCP]) and 15 with typical gross appearance of PCP. Topographically, 90 tumors were strictly within the 3V (82%); 20 developed at the infundibulo-tuberal region of the 3V floor (18%). Morphologically, 2 main types of recess were identified: (i) a long, narrow recess with either a duct-like or a tubular shape that reached the central region of the CP (n = 47, 42.5%); and (ii) a short recess extending only a few millimeters into the lesion, either with a duct-like or a shallow cleft-like morphology (n = 63, 57.5%). Thus, the presence of a basal recess represents a pathological hallmark of a subpopulation of 3V PCPs. The presumed nature and diagnostic significance of this novel finding is comprehensively addressed.

Persisting embryonal infundibular recess in a case of TITF-1 gene mutation

The thyroid transcription factor 1 (TITF-1) gene plays an important role in the development of the ventral forebrain, thyroid and lungs. Mutations of this gene are known to cause benign hereditary chorea (BHC) and can cause the full spectrum of abnormalities seen in the brain-thyroid-lung syndrome. Abnormalities of the ventral forebrain on imaging have been variably documented in the literature. Multiple previous reports describe a cystic pituitary mass, as well as duplication of the pituitary stalk and communication between an intrasellar cyst and the third ventricle. The initial MRI performed in our case was interpreted as an intrasellar cyst, but the high-resolution MRI performed later was able to resolve this as a persisting embryonal infundibular recess (PEIR), rather than the cystic pituitary mass which has previously been described. This case illustrates the role of the TITF-1 gene in the development of the pituitary and hypothalamus.

A Potential Concomitant Sellar Embryonic Remnant-Associated Collision Tumor: Systematic Review

BACKGROUND

Diagnosing the well-known concomitant Rathke's cleft cyst (RCC) and differentiating it from other sellar lesions are difficult because RCC is and other sellar lesions are closely related and represent a continuum from simple RCCs to more complex lesions. The purpose of this study is to better understand the adeno- and neurohypophysis adjacent to the par intermedia remnants and their role in the origin of the coexistence of these two distinct tumor neoplasias; to assess the incidence in different age groups; to categorize the pathohistological subtype, which can be incorporated in predictive/prognostic models; and finally, to evaluate the current evidence on collision tumors of the sellar embryonic remnant tract in terms of their biological behavior and pathology.

METHODS

Utilizing the PubMed database, data were collected from 1920 to 2019. Information about demographics, clinical characteristics, and age was summarized and analyzed by using univariable and multivariable models. The same cell type was observed regardless of whether the tumor was only one type or mixed types, and their histologic patterns were assessed.

RESULTS

The incidence rates were similar among patients stratified into three age subgroups: 40-49 years (24.57%), 50-59 years (19.54%), and older than 60 years (22.98%). We found that various types of sellar lesions, namely, squamous metaplasia (SM) + goblet cells (GC) (HR 46.326), foamy macrophages (FM) (HR 39.625), epithelial cells and multinucleated giant cells or cholesterin (EM) (HR 13.195), a cavernous portion of the right internal carotid artery (CP-ICA) (HR 9.427), epithelial cells with ciliated cuboidal (EC-CC) (HR 8.456), were independently associated with RCC pathological status. These divergent AUCs (0.848 for Hypo as RCC, 0.981 for RCC co PA, 0.926 for CD and CP co RCC) and subtypes of PA (HR 4.415, HR 2.286), Hypo (HR 3.310), CD and CP (HR 2.467), EC and DC and PG and SGR (HR 1.068), coexisting with the risk of a comorbid RCC lesion, may reflect the etiologic heterogeneity of coderivation and the different effects of some risk factors on tumor subtypes. Our analyses suggested that the greatest accuracy was observed for the pituitary adenoma subtype, with an AUC of 0.981 (95% confidence interval [CI]: 0.959-1.005), while the poorest accuracy was observed for aneurysms, with an AUC of 0.531 (95% CI: 0.104-0.958). We separately analyzed and confirmed the above results. Sensitivity analysis revealed no evidence of systematic bias due to missing data.

CONCLUSION

This study showed that the histopathological changes in patients with sellar embryonic remnant-associated collision tumors showed highly consistent epithelial cell replacement (renewal) (ciliated columnar epithelium to ciliated squamous epithelium to squamous epithelium) or accumulation, and the RCC cyst wall was similar in structure to the tracheobronchial airway epithelium, with progenitor cell characteristics. The collision accuracy between RCC and other tumors (PAs, craniopharyngioma, chordoma, etc.) is different; these characteristics constitute the theoretical basis for the postmigration development of the pharyngeal bursa.

Variation in the MRI appearance of the canine pituitary gland

A recent publication described pathological findings in the pituitary gland incidentally discovered during routine necropsies of the brain of dogs and cats; however, imaging characteristics of these lesions were not reported. Aims of this retrospective, observational study were to characterize MRI variants and incidental lesions in pituitary glands of dogs with no clinical signs of pituitary disease. Cranial MRIs from dogs with no suspicion of pituitary disease, based on history and presenting clinical signs, were retrieved from a veterinary teleradiology database during the period of January 2014 to January 2016. Images were reinterpreted by two observers and pituitary lesions were described based on consensus. A total of 580 scans were evaluated and pituitary lesions were detected in 78 dogs (13.44%). Pituitary cystic lesions were the most common finding and occurred in 31 dogs (5.34%). Of these 31 dogs, the majority (74%) were of toy or brachycephalic breed. Partial or total empty sella lesions were detected in 14 dogs (2.41%), and all of these were small or toy breeds. A significantly increased incidence of the partial empty sella lesion was found in male dogs (P = .034). Pituitary lesions greater than 1 cm occurred rarely (0.69%). There was a significant association between low-field (LF) MRI strength and detection of a partial or total empty sella lesion (P = .0112), and detection of a pituitary lesion greater than 1 cm (P = .0125). A significant difference was present between the MRI field strength (FS) that identified pituitary cysts and the FS that detected an empty sella (P = .0068), with the former being a high FS and the latter a LF strength. The findings from this study indicated that up to 13% of dogs with no presenting clinical signs of pituitary disease may have MRI pituitary lesions.

Persisting Embryonal Infundibular Recess in Morning Glory Syndrome: Clinical Report of a Novel Association

Morning glory syndrome is characterized by a congenital optic disc defect that resembles the eponymous flower. We present the MR imaging findings of 2 pediatric patients with morning glory disc anomaly and persisting embryonal infundibular recess, another rare malformative finding, a previously unreported association. Neuroradiologists should be aware of the possible presence of a persisting embryonal infundibular recess in patients with morning glory syndrome, to aid in the differential diagnosis including other pituitary malformations such as pituitary stalk duplication.