Pituicytoma with gelsolin amyloid deposition

Surgical approach to the treatment of pituicytoma. Report of five cases and a literature review

Background

Pituicytoma (PTs) is a rare tumor of the sella and suprasellar region, derived from the pituicytes of the neurohypophysis, having distinct histological characteristics of glial neoplasms. We reported, the clinical data, neuroimaging studies, surgical approaches and pathology in five patients with PTs and also, we reviewed the literature.

Methods

Retrospective chart from five consecutive patients with PTs treated at one University Hospital from 2016 to 2021 were reviewed. In addition, we conducted a search in PubMed/Medline databases using the term "Pituicytoma". Data regarding age, gender, pathological findings, and treatment modality applied were extracted.

Results

All patients were female, aged 29-63, complaining of headaches, visual loss and field defects, dizziness and normal or abnormal levels of circulating pituitary hormones. Magnetic Resonance Imaging (MRI) showed in all patients a sellar and suprasellar mass, which was removed through an endoscopic transsphenoidal approach. Our third patient had a subtotal resection followed by close observation. Histopathology showed a glial non-infiltrative tumors with spindle cells, and a final diagnosis of pituicytoma was made. After surgery, visual field defects in all patients were normalized, and in two patients normal levels of plasma hormones were restored. After a mean of three years follow-up, the patients were managed post-operatively through close clinical observation and serial MRI. None of the patients had recurrence of the disease.

Conclusion

PTs is a rare glial tumor of the sellar and suprasellar region that arises from neurohypophyseal pituicytes. Disease control may be achieved by total excision.

Pituicytoma: A rare tumor of the sella. A case report and review of literature for diagnosis and management

Background

Pituicytomas are rare tumors of the pituitary gland derived from the ependymal cells and line the pituitary stalk and posterior lobe. These tumors are located in the vulnerable regions of the brain: Either in the sellar or suprasellar area. The location marks the difference in the clinical features of the tumor. Here, we report a case of histopathologically diagnosed pituicytoma of the sellar region. Literature is also reviewed and discussed to gain a better understanding of this rare disease.

Case Description

A 24-year-old female presented to the outpatient department with complaints of headache, diplopia, dizziness, and decreased vision in the right eye for 6 months. Computed tomography scan brain without contrast showed a well-defined hyperdense lesion in the sella without associated bony erosion. Her magnetic resonance imaging showed well defined rounded lesion in the pituitary fossa which was isointense on T1-weighted image and hyperintense on T2-weighted images. A presumptive diagnosis of pituitary adenoma was made. She underwent endoscopic endonasal transsphenoidal resection of pituitary mass. Intraoperatively, normal pituitary gland was visualized and there was a grayish-green-colored, jelly like tumor which was pulled gently. On 9^th postoperative day, she presented with cerebrospinal fluid (CSF) rhinorrhea. She underwent endoscopic CSF leak repair. Her histopathology was concluded to be Pituicytoma.

Conclusion

Pituicytoma is an uncommon diagnosis. The surgical aim is to completely excise the tumor which results in complete cure, but incomplete resection may be performed due to high vascularity of this tumor. In case of incomplete excision, recurrence is common and adjuvant radiotherapy may be administered.

A novel hotspot of gelsolin instability triggers an alternative mechanism of amyloid aggregation

Gelsolin comprises six homologous domains, named G1 to G6. Single point substitutions in this protein are responsible for AGel amyloidosis, a hereditary disease causing progressive corneal lattice dystrophy, cutis laxa, and polyneuropathy. Although several different amyloidogenic variants of gelsolin have been identified, only the most common mutants present in the G2 domain have been thoroughly characterized, leading to clarification of the functional mechanism. The molecular events underlying the pathological aggregation of 3 recently identified mutations, namely A551P, E553K and M517R, all localized at the interface between G4 and G5, are here explored for the first time. Structural studies point to destabilization of the interface between G4 and G5 due to three structural determinants: β-strand breaking, steric hindrance and/or charge repulsion, all implying impairment of interdomain contacts. Such rearrangements decrease the temperature and pressure stability of gelsolin but do not alter its susceptibility to furin cleavage, the first event in the canonical aggregation pathway. These variants also have a greater tendency to aggregate in the unproteolysed forms and exhibit higher proteotoxicity in a C. elegans-based assay. Our data suggest that aggregation of G4G5 variants follows an alternative, likely proteolysis-independent, pathway.

Posterior pituitary tumours: patient outcomes and determinants of disease recurrence or persistence

OBJECTIVE

Posterior pituitary tumours (PPTs) are rare neoplasms with the four recognised subtypes unified by thyroid transcription factor -1 (TTF-1) expression, according to the 2017 WHO classification. Though traditionally defined as low-grade neoplasms, a substantial proportion of them show recurrence/persistence following surgery.

METHODS

We selected patients with PPTs in our cohort of 1760 patients operated for pituitary tumours over the past 10 years (2010-2019). The clinical, radiological, hormonal, histopathological profiles and long-term outcomes of the three cases identified (two pituicytomas and one spindle cell oncocytoma, SCO) were analysed. Following a literature review, data of all published cases with documented TTF-1 positive pituicytomas and SCOs were analysed to determine the predictors of recurrence/persistence in these tumours.

RESULTS

Patients presented with compressive features or hypogonadism. Two had sellar-suprasellar masses. One had a purely suprasellar mass with a pre-operative radiological suspicion of pituicytoma. Two were operated by transsphenoidal surgery and one transcranially guided by neuronavigation. Histopathology confirmed spindle cells in a storiform arrangement and low Ki67 index. Immunohistochemistry showed positive TTF-1, S-100 expression and variable positivity for EMA, vimentin and GFAP. Re-evaluation showed recurrence/persistence in two patients. A literature review of recurrent/persistent pituicytoma (n = 17) and SCO (n = 9) cases revealed clinical clues (headache for pituicytomas, male gender for SCO), baseline tumour size (≥20.5 mm with sensitivity exceeding 80%) and longer follow-up duration as determinants of recurrence/persistence.

CONCLUSION

PPTs are rare sellar masses with quintessential TTF-1 positivity. Recurrent/persistent disease following surgery is determined by greater tumour size at baseline and duration of follow-up. This warrants intensive and long-term surveillance in these patients.

Primary tumors of the posterior pituitary: A systematic review

In 2017, the World Health Organization established that pituicytoma, granular cell tumor (GCT), spindle cell oncocytoma (SCO) and sellar ependymomas (SE) are posterior pituitary tumors (PPT). They probably arise from the pituicytes and may constitute a unique histopathological entity. We carried out a systematic review using PubMed's database. A total of 266 patients with pathological diagnosis of PPT (135 pituicytomas, 69 GCT, 47 SCO, 8 SE and 7 mixed histology tumors) were analyzed. Gender distribution was identical and median age at diagnosis was 48 ± 21.8 years. Main presentation symptoms were visual disorders (n = 142; 58.1%), headache (n = 99; 40.5%), hypopituitarism (n = 84; 34.4%), hypercortisolism (n = 10; 4.1%), polyuriapolydipsia (n = 6; 2.4%) and acromegaly features (n = 5; 2.0%). On MRI, 122 (47.6%) patients showed sellar with suprasellar extension masses, 67 (23.1%) were suprasellar and 63 (24.6%) exclusively sellar. Median tumor size was 22.0 ± 14.2 mm. Two hundred sixty four patients underwent surgery, transphenoidal access was selected in 132 (64.4%) and craniotomy in 58 (28.3%). Complications were hypopituitarism (n = 70; 42.1%), diabetes insipidus (n = 55; 33.1%) and hemorrhage (n = 50; 30.1%). Tumor persisted in 93 patients (45.6%) and recurred in 13 (6.4%). Regarding comparison between main types of PPT, SCO patients were diagnosed later (60.0 vs 47.0 vs 47.0 years, p = 0.023), the tumor was larger 25.0 mm [10.8] vs 20.0 mm [14.2] vs 2.0 mm [15.0] and they were frequently sellar with suprasellar extension tumors (71.7% vs 46.2% vs 32.8%, p = 0.003) compared to pituicytoma and GCT. In conclusion, PPT are rare tumors and have been misdiagnosed mainly as non-functioning pituitary adenomas. Different types of PPT share similar epidemiology, clinical manifestations and surgical outcomes. Surgery is the only curative option but complications and subtotal resection are common.

Clinical features, diagnosis and therapy of pituicytoma: an update

BACKGROUND

Pituicytomas (PTs) are extremely rare, low-grade glial tumors closely related to the neurohypophyseal axis. Definite conclusions concerning the optimal diagnostic and therapeutic approach to these neoplasms are lacking to date, as most of this information has been presented as case reports.

METHODS

Retrospective review of case reports published in the scientific literature to date, including a new illustrative example treated in our department.

RESULTS

116 cases were collected. PTs had a higher prevalence in the fifth and sixth decades of life, with a slight male predominance. Main symptoms, which tended to be progressive, included visual field defects and pituitary-hypothalamic dysfunction. Radiologically, PTs were found anywhere along the hypothalamic-pituitary axis mimicking other, more frequent tumors growing in this anatomical region. Surgical treatment included both transcranial or transsphenoidal approaches, and resulted in gross total resection and morbidity rates of 46.8 and 59%, respectively; the latter essentially consisted in anterior and posterior pituitary dysfunction, with limited impact on daily quality of life.

CONCLUSIONS

Due to both low frequency and the absence of pathognomonic clinical and/or radiological features, formulating a suspicion diagnosis of PT represents a considerable challenge even for experienced professionals. The indication for treatment should be made on an individual basis, but it is inescapable in the presence of a visual field defect. The surgical approach has to be tailored according to the topography of the tumor and preoperative symptoms; the greatest challenges in accomplishing a gross total removal are represented by the degree of adherence and vascularization of the PT.

Gelsolin pathogenic Gly167Arg mutation promotes domain-swap dimerization of the protein

AGel amyloidosis is a genetic degenerative disease characterized by the deposition of insoluble gelsolin protein aggregates in different tissues. Until recently, this disease was associated with two mutations of a single residue (Asp187 to Asn/Tyr) in the second domain of the protein. The general opinion is that pathogenic variants are not per se amyloidogenic but rather that the mutations trigger an aberrant proteolytic cascade, which results in the production of aggregation prone fragments. Here, we report the crystal structure of the second domain of gelsolin carrying the recently identified Gly167Arg mutation. This mutant dimerizes through a three-dimensional domain swapping mechanism, forming a tight but flexible assembly, which retains the structural topology of the monomer. To date, such dramatic conformational changes of this type have not been observed. Structural and biophysical characterizations reveal that the Gly167Arg mutation alone is responsible for the monomer to dimer transition and that, even in the context of the full-length protein, the pathogenic variant is prone to form dimers. These data suggest that, in addition to the well-known proteolytic-dependent mechanism, an alternative oligomerization pathway may participate in gelsolin misfolding and aggregation. We propose to integrate this alternative pathway into the current model of the disease that may also be relevant for other types of AGel amyloidosis, and other related diseases with similar underlying pathological mechanisms.

Pituicytoma-An outlook on possible targeted therapies

INTRODUCTION

Pituicytoma is a rare neoplasm of the sella region. Tumor resection is the primary treatment option, but remains subtotal due to excessive bleeding in many cases. The search for alternative or additional treatment regimens is necessary.

AIMS

We aimed to determine the receptor expression of pituicytoma to find alternatives or supplements to surgical therapy in the use of targeted therapies.

METHODS

Pituicytoma samples were collected from three institutions between 2006 and 2015 and were stained for vascular endothelial growth factors (VEGF), thyroid transcription factor (TTF1), and somatostatin receptors (SSTR 2/3/5). The stains were classified from 0=no staining to +++=strong staining. A complementary retrospective analysis of the patient charts regarding sex, age, and primary symptoms, pituitary function, and perioperative complications was performed.

RESULTS

Ten samples were analyzed; mean patient age was 57.8 years SD 16.3 years. Seven samples were acquired from male patients (one relapse) and three from female. All tumors stained strongly positive (+++) for VEGF-R. Six samples stained positive for TTF1. As for somatostatin receptors, three samples were slightly positive for SSTR 2; seven were negative. SSTR 3 was + in one, three were ++, three were +++, and three were 0. SSTR 5 stained +++ in 1, ++ in 5, + in 1, and 0 in three patients.

CONCLUSIONS

Pituicytomas were generally positive for VEGFR and showed regular expression of SSTR 3 and 5 indicating a possible treatment option through targeted therapies in cases where resection remains insufficient. Further research is necessary as to whether tumor growth can be inhibited using these pathways.

DHA-mediated regulation of lung cancer cell migration is not directly associated with Gelsolin or Vimentin expression

AIMS

Deaths associated with cancer metastasis have steadily increased making the need for newer, anti-metastatic therapeutics imparative. Gelsolin and vimentin, actin binding proteins expressed in metastatic tumors, participate in actin remodelling and regulate cell migration. Docosahexaenoic acid (DHA) limits cancer cell proliferation and adhesion but the mechanisms involved in reducing metastatic phenotypes are unknown. We aimed to investigate the effects of DHA on gelsolin and vimentin expression, and ultimately cell migration and proliferation, in this context.

MAIN METHODS

Non-invasive lung epithelial cells (MLE12) and invasive lung cancer cells (A549) were treated with DHA (30μmol/ml) or/and 8 bromo-cyclic adenosine monophosphate (8 Br-cAMP) (300μmol/ml) for 6 or 24h either before (pre-treatment) or after (post-treatment) plating in transwells. Migration was assessed by the number of cells that progressed through the transwell. Gelsolin and vimentin expression were measured by Western blot and confocal microscopy in cells, and by immunohistochemistry in human lung cancer biopsy samples.

KEY FINDINGS

A significant decrease in cell migration was detected for A549 cells treated with DHA verses control but this same decrease was not seen in MLE12 cells. DHA and 8 Br-cAMP altered gelsolin and vimentin expression but no clear pattern of change was observed. Immunofluorescence staining indicated slightly higher vimentin expression in human lung tissue that was malignant compared to control.

SIGNIFICANCE

Collectively, our data indicate that DHA inhibits cancer cell migration and further suggests that vimentin and gelsolin may play secondary roles in cancer cell migration and proliferation, but are not the primary regulators.

Analysis of gelsolin expression pattern in developing chicken embryo reveals high GSN expression level in tissues of neural crest origin

Gelsolin is one of the most intensively studied actin-binding proteins. However, in the literature comprehensive studies of GSN expression during development have not been performed yet in all model organisms. In zebrafish, gelsolin is a dorsalizing factor that modulates bone morphogenetic proteins signaling pathways, whereas knockout of the gelsolin coding gene, GSN is not lethal in murine model. To study the role of gelsolin in development of higher vertebrates, it is crucial to estimate GSN expression pattern during development. Here, we examined GSN expression in the developing chicken embryo. We applied numerous methods to track GSN expression in developing embryos at mRNA and protein level. We noted a characteristic GSN expression pattern. Although GSN transcripts were present in several cell types starting from early developmental stages, a relatively high GSN expression was observed in eye, brain vesicles, midbrain, neural tube, heart tube, and splanchnic mesoderm. In older embryos, we observed a high GSN expression in the cranial ganglia and dorsal root ganglia. A detailed analysis of 10-day-old chicken embryos revealed high amounts of gelsolin especially within the head region: in the olfactory and optic systems, meninges, nerves, muscles, presumptive pituitary gland, and pericytes, but not oligodendrocytes in the brain. Obtained results suggest that GSN is expressed at high levels in some tissues of ectodermal origin including all neural crest derivatives. Additionally, we describe that silencing of GSN expression in brain vesicles leads to altered morphology of the mesencephalon. This implies gelsolin is crucial for chicken brain development.