Oncogene-induced senescence in meningiomas-an immunohistochemical study.

PURPOSE: Meningiomas are tumours originating from meningothelial cells, the majority belonging to grade 1 according to the World Health Organization classification of the tumours of the Central Nervous System. Factors contributing to the progression to the higher grades (grades 2 and 3) have not been elucidated yet. Senescence has been proposed as a potential mechanism constraining the malignant transformation of tumours. Senescence-associated beta-galactosidase (SA-ß-GAL) and inhibitors of cyclin-dependent kinases p16 and p21 have been suggested as senescence markers. METHODS: We analysed 318 meningiomas of total 343 (178 grade 1, 133 grade 2 and 7 grade 3). Tissue microarrays were constructed and stained immunohistochemically, using antibodies for SA-ß-GAL, p16 and p21. RESULTS: The positive correlation of the tumour grade with the expression of p16 (p = 0.016) and SA-ß-GAL (p = 0.002) was observed. The expression of p16 and SA-ß-GAL was significantly higher in meningiomas grade 2 compared to meningiomas grade 1 (p = 0.006 and p = 0.004, respectively). SA-ß-GAL positivity positively correlated with p16 and p21 in the whole cohort. In grade 2 meningiomas, a positive correlation was only between SA-ß-GAL and p16. Correlations of senescence markers in meningiomas grade 2 were not present. CONCLUSION: Our findings suggest the senescence activation in meningiomas grade 2 as a potential mechanism for the restraining of tumour growth and give hope for applying of promising senolytic therapy.

Secondary vs. primary pituitary xanthogranulomas: which yellow is more mellow?

Pituitary xanthogranulomatomas (XG) are a rare pathological entity caused by accumulation of lipid laden macrophages and reactive granuloma formation usually triggered by cystic fluid leakage or hemorrhage. Our aim was to compare clinical characteristics and presenting features of patients with secondary etiology of XG and those with no identifiable founding lesion (primary -"pure" XG) in order to gain new insights into this rare pituitary pathology. In a retrospective review of 714 patients operated for sellar masses, at tertiary center, we identified 16 (2.24%) with histologically confirmed diagnosis of pituitary XG over the period of 7 years (2015-2021). Patients were further analyzed according to XG etiology: "pure"- XG (n = 8) with no identifiable founding lesion were compared to those with histological elements of pituitary tumor or cyst - secondary XG (n = 8). We identified 16 patients (11 male), mean age 44.8 ± 22.3 years, diagnosed with pituitary XG. Secondary forms were associated with Ratke's cleft cyst (RCC, n = 2) and pituitary adenoma (PA, n = 6). The most common presenting features in both groups were hypopituitarism (75%), headache (68.5%) and visual disturbances (37.5%). Predominance of male sex was noted (males 68.75%, females 31.25%), especially in patients with primary forms. Patients with primary pituitary XG were all males (p = 0.0256) and more frequently affected by panhypopituitarism (87.5% vs. 25%, p = 0.0406) compared to patients with secondary causes. Hyperprolactinemia was noted in pituitary tumor group with secondary etiology only (p = 0.0769). Majority of lesions were solid on magnetic resonance imaging - MRI (81.25%). Distinct clinical phenotype was observed dependent on the etiology of XG.

The sellar region as presenting theater for hematologic malignancies-A 17-year single-center experience.

Hematological neoplastic mass lesions of the sellar region are rare. We identified five cases of hematological malignancy with first presentation in the sellar region from our departmental database of 1,405 patients (0.36%) with sellar lesions diagnosed over the 17-year period (2005-2021). All patients were females (mean age 55.2 ± 3.4 years). One patient had multiple myeloma (MM), one patient had acute myeloid leukemia (AML), while three other patients had lymphoma (intravascular lymphoma (IVL, n = 1) or non-Hodgkin's lymphoma (NHL, n = 2). Most patients presented with ophthalmoplegia, and one patient with diabetes insipidus (DI), with short duration of symptoms (median 30 days). All patients had an elevated erythrocyte sedimentation rate and altered blood count, while patients with lymphoma had elevated lactate dehydrogenase (LDH). Sellar mass was demonstrated in three patients while the patient with IVL had an empty sella and in the AML patient posterior lobe T1W hyperintensity was lost. Two patients (IVL and NHL) presented with multiple anterior pituitary deficiencies and one patient (AML) had DI. All patients were treated with chemotherapy. Two patients responded well to treatment (one had reversed hypopituitarism), while three patients died. Differential diagnosis of sellar-parasellar pathology should include suspicion of hematological malignancy, particularly in patients with short duration of nonspecific symptoms, neurological signs (ophthalmoplegia), blood count alterations and LDH elevation, pituitary dysfunction and imaging features atypical for pituitary adenoma. Early diagnosis is crucial for timely initiation of hematological treatment aimed at inducing disease remission and partial or full recovery of pituitary function.

Histopathology of Parasellar Neoplasms.

The anatomical and histological complexity of the parasellar region as well as the presence of embryonic remnants determine the huge diversity of parasellar neoplasms. Some of them are only located in the parasellar region, whereas others can occur elsewhere, within or outside the central nervous system. Their spectrum ranges from histologically benign and low-grade malignant to high-grade malignant tumours. Although rare, metastases can pose differential diagnostic dilemmas. The severity of the clinical picture, the challenges of surgery and the risk of adverse sequelae related to surgery or radiotherapy make parasellar tumours interesting entities for the clinicians irrespective of their histological malignancy grade. Due to the different cell origins of parasellar tumours, the World Health Organization classification system does not categorise them as a distinct group. Detailed criteria for classification and malignancy grading are presented in the classification systems covering central nervous system tumours, haematological malignancies and tumours of the soft tissue and bone. In the last few years, molecular genetic features have been integrated into the diagnosis of several types of the parasellar tumours enhancing diagnostic accuracy and providing information of the value for targeting therapies. In this review, we will present histopathological and molecular genetic features, updated classification criteria and recent advances in the diagnostics and rationale for novel pharmacological therapies of selected types of parasellar neoplasms.

Hypopituitarism in five PROP1 mutation siblings: long-lasting natural course and the effects of growth hormone replacement introduction in middle adulthood.

Twenty years after the first description of combined hypopituitarism (CPHD) caused by PROP1 mutations, the phenotype of affected subjects is still challenging for clinicians. These patients suffer from pituitary hormone deficits ranging from IGHD to panhypopituitarism. ACTH deficiency usually develops later in life. Pituitary size is variable. PROP1 mutation is the most frequent in familial congenital hypopituitarism (CH). Reports on initiation of hormonal replacement including growth hormone (GH) in adults with CH are scarce. We identified 5 adult siblings with CPHD due to PROP1 mutation (301-302delAG), aged 36-51 years (4 females), never treated for hormone deficiencies. They presented with short stature (SD from - 3.7 to - 4.7), infantile sexual characteristic, moderate abdominal obesity and low bone mineral density in 3 of them. Complete hypopituituitarism was confirmed in three siblings, while two remaining demonstrated GH, TSH, FSH and LH deficiencies. Required hormonal replacement including rhGH was initiated in all patients. After several months necessity for hydrocortisone replacement developed in all patients. After 2 years of continual replacement therapy, BMD and body composition (measured by DXA-dual X-ray absorptiometry) improved in all subjects, most prominently in two younger females and the male sibling. Besides rhGH therapy, these three patients have received sex hormones contributing to the favorable effect. The male sibling was diagnosed with brain glioblastoma two years following complete hormonal replacement. This report provides important experience regarding hormonal replacement, particularly rhGH treatment, in adults with long-term untreated CH. Beneficial effect of such therapy are widely acknowledged, yet these subjects could be susceptible to certain risks of hormonal treatment initiated in adulthood. Careful and continual clinical follow-up is thus strongly advised.

Bridging the Gap with Clinicians: The Issue of Underrecognition of Pathologists and Radiologists as Scientific Authors in Contemporary Medical Literature.

The purpose of this study was to evaluate recognition of pathologists and radiologists as coauthors in case reports in the field of surgical oncology. The MEDLINE database was searched for all full free text case reports involving human material published from April 1, 2011 until March 31, 2016, using search terms: "case report" + "tumors" + "surgery" + "malignant". The search strategy identified a total of 1427 case reports of which 907 were included in this analysis. Of 807 articles with histopathological images and/or descriptions, 352 (43.6%) did not acknowledge or include the pathologist as a coauthor. Of 662 case reports with radiographic images and/or their description, 537 (81.1%) did not list the radiologist as coauthor nor acknowledge them. In case reports containing histopathological images, significantly more pathologists were either listed as coauthors or acknowledged compared to those who were not (Z = 5.128; p = 0.001). However, among case reports containing radiographic images, there were significantly less articles either listing radiologists as coauthors or acknowledging them compared to a larger proportion of articles in which radiologists were omitted (Z = - 22.646; p = 0.001). In conclusion, pathologists and radiologists are underrecognized as coauthors in surgical oncology case reports in spite of obvious proof of their contribution to manuscript preparation. When involved in research and publishing, all physicians should be aware of fair and honest collaboration with specialists in other clinical and non-clinical disciplines to better serve the scientific community.

Histopathological classification of non-functioning pituitary neuroendocrine tumors.

Non-functioning pituitary neuroendocrine tumors do not cause endocrine symptoms related to hypersecretion of adenohypophyseal hormones and are clinically characterized by symptoms due to growing sellar tumor mass. Histopathological classification of this tumor group has always been challenging due to their heterogeneity, limited knowledge on their biology, and diverse methodological problems. We have searched PubMed database for data related to the histopathological classification of non-functioning pituitary tumors and methods for its application. Principles of the classification and grading presented in the recently released 4th edition of the World Health Organization classification of endocrine tumors have been summarized. Based on the expression of anterior pituitary hormones and pituitary specific transcription factors, gonadotroph tumors dominate within the group of clinically non-functioning tumors, followed by corticotroph type; however, other less common types of the non-functioning tumors can be identified. Assessment of tumor cell proliferation is important to identify "high-risk adenomas." A few subtypes of non-functioning tumors belong to the category of potentially aggressive tumors, independent of the cell proliferation rate. Here, we present up to date criteria for the classification of clinically non-functioning pituitary tumors, offer a diagnostic approach for the routine clinical use, and emphasize a need for inclusion of prognostic and predictive markers in the classification.

Single center study of 53 consecutive patients with pituitary stalk lesions.

BACKGROUND: The etiological spectrum of pituitary stalk lesions (PSL) is wide and yet specific compared to the other diseases of the sellar and suprasellar region. Because of the pituitary stalk's (PS) critical location and role, biopsies of these lesions are rarely performed, and their underlying pathology is often a conundrum for clinicians. A pituitary MRI in association with a clinical context can facilitate their diagnosis. AIM: To present the various causes of PSL-their clinical, hormonal, histopathological, and MRI characteristics in order to gain better insight into this pathology. METHOD: A retrospective observational study consisting of 53 consecutive patients with PSL of the mean age 32 ± 4.2 years (range 6-67), conducted at the Department for Neuroendocrinology, Clinical Center of Serbia 2010-2018. RESULTS: Congenital malformations were the most common cause of PSL in 25 of 53 patients (47.1%), followed by inflammatory (9/53; 16.9%) and neoplastic lesions (9/53; 16.9%). The exact cause of PSL was established in 31 (58.4%) patients, of whom 23 were with congenital PS abnormalities and 8 with histopathology of PSL (7 neoplastic and 1 Langerhans Cell Hystiocytosis). A probable diagnosis of PSL was stated in 12 patients (22.6%): 6 with lymphocytic panhypophysitis, while Rathke cleft cyst, tuberculosis, dissemination of malignancy in PS were each diagnosed in 2 patients. In 10 patients (18.8%), the etiology of PSL remained unknown. CONCLUSION: Due to the inability of establishing an exact diagnosis, the management and prognosis of PSL are difficult in many patients. By presenting a wide array of causes implicated in this condition, we believe that our study can aid clinicians in the challenging cases of this pathology.

Expression of G1/S-cyclins and cyclin-dependent kinase inhibitors in actinic keratosis and squamous cell carcinoma.

BACKGROUND: Actinic keratosis (AK) and Bowen's disease (squamous cell carcinoma in situ, SCCIS) are pre-invasive stages in the development of squamous cell carcinoma (SCC). METHODS: Immunohistochemical study of cyclin D1, cyclin E, p16(INK4a) and p21(Cip1) (/Waf1) in AK (53 cases), SCCIS (16 cases) and SCC (40 cases), in relation to the type of the lesion and SCC prognostic parameters (grade, diameter and thickness). RESULTS: Diffuse cyclin D1 distribution was more frequent in SCCIS and SCC than in AK (p = 0.03) and similar pattern was observed for p16(INK4a) . For cyclin E, central distribution dominated in SCC compared with the AK (p = 0.001) and SCCIS (p = 0.03). p21(Cip1) (/Waf1) displayed suprabasal distribution more frequently in AK than in SCCIS (p = 0.001) and SCC (p = 0.0004). Semiquantitative assessment showed more positive cells in AK (p = 0.04) and SCCIS (p = 0.04) than in SCC for cyclin E. SCC with diameter over 20 mm and those thicker than 6 mm revealed higher labeling index with p16(INK4a) and p21(Cip1) (/Waf1) , respectively. CONCLUSIONS: Our results suggest different alterations for p16(INK4a) and p21(Cip1) (/Waf1) in AK, SCCIS and SCC. Immunostaining distribution showed closer correlation with the type of the lesion, whereas percentage of positive cells displayed better association with the SCC prognostic parameters.

The impact of TP53 and RAS mutations on cerebellar glioblastomas.

Cerebellar glioblastoma (cGBM) is a rare, inadequately characterized disease, without detailed information on its molecular basis. This is the first report analyzing both TP53 and RAS alterations in cGBM. TP53 mutations were detected in more than half of the samples from our cohort, mainly in hotspot codons. There were no activating mutations in hotspot codons 12/13 and 61 of KRAS and HRAS genes in cGBM samples but we detected alterations in other parts of exons 2 and 3 of these genes, including premature induction of STOP codon. This mutation was present in 3 out of 5 patients. High incidence of RAS mutations, as well as significantly longer survival of cGBM patients compared to those with supratentorial GBM suggest that cGBM may have different mechanisms of occurrence. Our results suggest that inactivation of TP53 and RAS may play an important role in the progression of cerebellar GBM.

Plurihormonal Pituitary Neuroendocrine Tumours - A Single Centre Experience.

Introduction. Plurihormonal pituitary neuroendocrine tumours (PitNET)/adenomas are pituitary neuroendocrine tumours composed of monomorphous cell populations expressing anterior pituitary transcription factors and/or hormones belonging to more than one cell lineage. Studies dedicated to plurihormonal tumours are rare and quite heterogenous with their results, bearing in mind changes in diagnostic criteria and inconsistent use of antibodies for anterior pituitary transcription factors in the diagnostic immunohistochemical panel. Material and Methods. We retrospectively analysed all patients surgically treated for PitNETs from 2016 to July 2022 in a tertiary healthcare institution. All tumours previously diagnosed PitNETs with the word "plurihormonal" were re-examined and potentially re-classified, according to 2022 WHO classification of endocrine tumours. Results. Among 721 patients surgically treated for PitNET in 5.5 years period, the diagnosis of plurihormonal PitNET was established in 11 tumours (1.3%). All tumours showed diffuse and intensive positivity for anterior pituitary transcription factors PIT1 and SF1. Clinically, all patients presented with acromegaly. Conclusions. Retrospective studies related to newly defined plurihormonal PitNETs with a reassessment of diagnoses are necessary due to their rarity and ambition to investigate their origin and biological behaviour. The fact that the majority of plurihormonal PitNETs are clinically presented with acromegaly and show simultaneous positivity to PIT1 and SF1 transcription factors deserve special attention and need for further research in larger cohorts of these exceptional tumours.

A dermatological perspective: eosinophilic eruption of hematoproliferative disease as a clinical and histological dilemma.

The emergence of de novo or recurrent cutaneous eruptions in individuals with hematological diseases presents a challenge when determining whether they indicate secondary dissemination or an unrelated diagnosis. Eosinophilic eruption of hematoproliferative disease is a rare nonspecific manifestation accompanying lymphoproliferative disorders, including chronic lymphocytic leukemia (CLL). We present the case of a 70-year-old man with CLL in remission (previously treated with two 6-month cycles of fludarabine-cyclophosphamide plus rituximab, 2 and 5 years earlier) with an acute, disseminated polymorphic skin eruption. Skin biopsies from two sites (bulla and infiltrated nodule) were taken for histopathological examination. The pathologist reported giant spongiform vesicle formation with eosinophils with dermal and hypodermal inflammatory infiltrate composed of lymphocytes (predominantly T cells, fewer B cells) and eosinophils. Secondary neoplasm dissemination and sarcoidosis were excluded by means of immunohistochemistry. A diagnosis of eosinophilic eruption of hematoproliferative disease in the CLL patient post-chemotherapy and without active disease was established. Two weeks after skin remission, the patient worsened with enlarged lymph nodes and a leukocyte count of 291 × 10^9/l. CLL relapse was confirmed. Leukocytapheresis was performed and ibrutinib 140 mg three times daily was prescribed. Our case underscores the importance of recognizing this relatively common but underreported eosinophilic eruption associated with hematoproliferative diseases.

Intraorbital ganglioglioma of optic nerve in a patient with neurofibromatosis type 1.

We report the case of an orbital optic nerve gangliogoma in a 55-year-old woman with neurofibromatosis type 1 (NF1). Clinical course neuroimaging findings, pathology, and treatment options of gangliogloma are discussed and contrasted with pilocytic astrocytomas of the optic nerve, a much more frequent visual pathway neoplasm in NF1 patients.

Expression of kisspeptin and KISS1 receptor in pituitary neuroendocrine tumours - an immunohistochemical study.

INTRODUCTION: Pituitary neuroendocrine tumours (PitNETs), traditionally designated as pituitary adenomas, show elatively frequent invasive growth with exceptional metastatic potential, the causes of which are not entirely elucidated. Kisspeptins, which perform their activity through KISS1 receptor (KISS1R), are recognised as metastatic suppressors in many malignant tumours. This study aimed to investigate the immunohistochemical expression of kisspeptin and KISS1R in different types of PitNETs and to compare it with the expression in the normal anterior pituitary, using tissue microarray. MATERIAL AND METHODS: The experimental group consisted of 101 patients with PitNETs, with 45 (37.3%) being of gonadotroph, 40 (33.9%) somatotroph, 4 (3.4%) corticotroph, 4 (3.4%) thyrotroph, 3 (2.5%) lactotroph, and 6 (5.1%) null-cell type. The control group consisted of anterior pituitary tissue accidentally removed during the surgery for PitNETs in 17 patients. RESULTS: Kisspeptin expression was observed in both experimental and control groups, without statistically significant differences in the staining intensity. Negative kisspeptin staining was detected in 10 (9.9%), weak in 79 (78.2%), and moderate in 12 tumours (11.9%); none of the tumours had strong staining intensity. The weak staining intensity was predominant in all PitNET types except thyrotroph tumours. Significant statistical difference in terms of kisspeptin expression between types of PitNET and the control group was not observed. Immunohistochemical expression of KISS1R was not observed in the control group or in the experimental group. CONCLUSIONS: We conclude that immunohistochemistry, as a method, cannot confirm the involvement of kisspeptin in tumourigenesis and aggressiveness of PitNETs, but potentially supports its antimetastatic role. The absence of KISS1R immunohistochemical expression in all anterior pituitaries and PitNETs in our cohort needs verification through the use of different procedures designed for the detection of the presence and localisation of proteins in the cell.

Mapping the journey of transition: a single-center study of 170 childhood-onset GH deficiency patients.

OBJECTIVE: To analyze metabolic parameters, body composition (BC), and bone mineral density (BMD) in childhood-onset GH deficiency (COGHD) patients during the transition period (TP). DESIGN: Single- center, retrospective study was performed on 170 consecutive COGHD patients (age 19.2 ± 2.0 years, range 16-25) transferred after growth completion from two pediatric clinics to the adult endocrine unit. Two separate analyses were performed: (i) cross-sectional analysis of hormonal status, metabolic parameters, BC, and BMD at first evaluation after transfer from pediatrics to the adult department; (ii) longitudinal analysis of BC and BMD dynamics after 3 years of GH replacement therapy (rhGH) in TP. RESULTS: COGHD was of a congenital cause (CONG) in 50.6% subjects, tumor-related (TUMC) in 23.5%, and idiopathic (IDOP) in 25.9%. TUMC patients had increased insulin and lipids levels (P < 0.01) and lower Z score at L-spine (P < 0.05) compared to CONG and IDOP groups. Patients treated with rhGH in childhood demonstrated lower fat mass and increased BMD compared to the rhGH-untreated group (P < 0.01). Three years of rhGH after growth completion resulted in a significant increase in lean body mass (12.1%) and BMD at L-spine (6.9%), parallel with a decrease in FM (5.2%). CONCLUSION: The effect of rhGH in childhood is invaluable for metabolic status, BC, and BMD in transition to adulthood. Tumor-related COGHD subjects are at higher risk for metabolic abnormalities, alteration of body composition, and decreased BMD, compared to those with COGHD of other causes. Continuation of rhGH in transition is important for improving BC and BMD in patients with persistent COGHD.

Corticotroph Aggressive Pituitary Tumors and Carcinomas Frequently Harbor ATRX Mutations.

CONTEXT: Aggressive pituitary tumors (APTs) are characterized by unusually rapid growth and lack of response to standard treatment. About 1% to 2% develop metastases being classified as pituitary carcinomas (PCs). For unknown reasons, the corticotroph tumors are overrepresented among APTs and PCs. Mutations in the alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene, regulating chromatin remodeling and telomere maintenance, have been implicated in the development of several cancer types, including neuroendocrine tumors. OBJECTIVE: To study ATRX protein expression and mutational status of the ATRX gene in APTs and PCs. DESIGN: We investigated ATRX protein expression by using immunohistochemistry in 30 APTs and 18 PCs, mostly of Pit-1 and T-Pit cell lineage. In tumors lacking ATRX immunolabeling, mutational status of the ATRX gene was explored. RESULTS: Nine of the 48 tumors (19%) demonstrated lack of ATRX immunolabelling with a higher proportion in patients with PCs (5/18; 28%) than in those with APTs (4/30;13%). Lack of ATRX was most common in the corticotroph tumors, 7/22 (32%), versus tumors of the Pit-1 lineage, 2/24 (8%). Loss-of-function ATRX mutations were found in all 9 ATRX immunonegative cases: nonsense mutations (n = 4), frameshift deletions (n = 4), and large deletions affecting 22-28 of the 36 exons (n = 3). More than 1 ATRX gene defect was identified in 2 PCs. CONCLUSION: ATRX mutations occur in a subset of APTs and are more common in corticotroph tumors. The findings provide a rationale for performing ATRX immunohistochemistry to identify patients at risk of developing aggressive and potentially metastatic pituitary tumors.

Clinical case seminar: Familial intracranial germinoma.

BACKGROUND: Intracranial germinomas (ICG) are uncommon brain neoplasms with extremely rare familial occurance. Since ICG invades hypothalamus and/or pituitary, the endocrine dysfunction is one of the common determinants of these tumors. We presented two brothers with the history of ICG. Patient 1 is a 25-year-old male who had been suffering from the weakness of the right half of his body at the age of 18. Cranial MRI revealed mass lesion in the left thalamus. He underwent neurosurgery, tumor was removed completely. Histopathological (HP) and immunohistochemical analyses verified the diagnosis of pure germinoma. He experienced complete remission of the tumor after a radiation therapy. At the age of 22 the diagnosis of isolated growth hormone deficiency (IGHD) was established and GH replacement was initiated. Patient 2 is a 20-year old boy who was presented with diabetes insipidus at the age of 12. MRI detected tumor in the third ventricle and pineal region. After the endoscopic tumor biopsy the HP diagnosis was pure germinoma. He received chemotherapy followed by radiotherapy, and treated with GH during childhood. At the age of 18 GH replacement was reintroduced. A six month follow-up during the next two years in both brothers demonstrated the IGF1 normalization with no MRI signs of tumor recurrence. CONCLUSION: To the best of our knowledge so far, only six reports have been published related to familial ICG. The presented two brothers are the first report of familial ICG case outside of Japan. They are treated successfully with GH therapy in adult period. < /p > < p >.

All that glitters on PET is not cancer! 18F-deoxy-glucose avidity versus tumor biology: pituitary incidentaloma in a survivor of two previous unrelated malignancies.

INTRODUCTION: 18F-deoxy-glucose positron emission tomography combined with computed tomography (18F-FDG PET/CT) is routinely used in the detection of malignant disease based on the property of malignant cells to fuel their growth and replication by increased glucose uptake. Malignant lesions are rare in the sellar region, while pituitary adenomas are the most common pathology. These are benign neoplasms with insidious onset and low proliferation activity, and therefore are only exceptionally detected by 18F-FDG PET/CT. Studies that compare the biology of pituitary adenomas and their radiological properties using PET/CT are still lacking. CASE REPORT: We investigate and discuss tumour biology in light of increased 18F-FDG avidity in a symptom-free, 70-year-old male patient, previously treated for two different malignancies (lung and rectal). Increased tracer accumulation in the sellar region was incidentally detected on a follow-up 18F-FDG PET/CT scan. Additional MRI disclosed pituitary adenoma. Normal hormonal status was found, consistent with the diagnosis of non-functioning pituitary adenoma. Analysis of tumour tissue after pituitary surgery confirmed a silent gonadotroph adenoma with low proliferation index. Low expression of oncogene-induced senescence markers did not support senescence as the explanation for the tumour's low proliferative activity although it was in consonance with the hormonal activity. CONCLUSIONS: Pituitary adenomas can manifest as hypermetabolic foci on 18F-FDG PET/CT imaging with increased tracer uptake even in indolent, clinically silent pituitary adenomas with low mitotic activity. Special attention should be paid to evaluation of 18F-FDG avid pituitary adenomas in patients with multiple malignancies, bearing in mind that avidity does not always mirror its biological behaviour.

Oncogene-Induced Senescence in Pituitary Adenomas--an Immunohistochemical Study.

Oncogene-induced senescence (OIS) serves as an initial barrier to cancer development, being proposed as a possible explanation for the usually benign behavior of the pituitary adenomas. We aimed to explore the immunohistochemical expression of the OIS markers, senescence-associated lysosomal ß-galactosidase (SA-ß-GAL), p16, and p21 in different types of 345 pituitary adenomas and compared it with the expression in the normal pituitary and in the specimens from the repeated surgeries. SA-ß-GAL was overexpressed in the pituitary adenomas, compared to the normal pituitaries. Growth hormone (GH) producing adenomas showed the strongest SA-ß-GAL, with densely granulated (DG)-GH adenomas more reactive than the sparsely granulated (SG). Nuclear p21 was decreased in the adenomas, except for the SG-GH adenomas that had higher p21 than the normal pituitaries and the other adenomas. p16 was significantly lower in the adenomas, without type-related differences. SA-ß-GAL was slightly lower and p16 slightly higher in the recurrences. Our findings indicate alterations of the senescence program in the different types of pituitary adenomas. Activation of senescence in the pituitary adenomas presents one possible explanation for their usually benign behavior, at least in the GH adenomas that show a synchronous increase of two OIS markers. However, subdivision into GH adenoma subtypes reveals differences that reflect complex regulatory mechanisms influenced by the interplay between the granularity pattern and the hormonal factors, with possible impact on the different clinical behavior of the SG- and DG-GH adenoma subtypes. p16 seems to have a more prominent role in the pituitary tumorigenesis than in the senescence. Recurrent growth in a subset of the pituitary adenomas is not associated with consistent changes in the senescence pattern.