Pseudoacromegaly-A challenging entity in the endocrine clinic: A systematic review.

OBJECTIVE: Pseudoacromegaly encompasses conditions with features of acromegaly/gigantism, but no growth hormone (GH) or insulin-like growth factor-1 (IGF-1) excess. We aimed to review published pseudoacromegaly cases evaluated due to clinical suspicion of acromegaly. DESIGN/PATIENTS: PubMed/Medline search was conducted to identify reported pseudoacromegaly cases, which were systematically reviewed to ensure they met eligibility criteria: (1) presentation suggestive of acromegaly; (2) acromegaly excluded based on normal GH, IGF-1 and/or GH suppression on oral glucose tolerance test (OGTT-GH); (3) diagnosis of the pseudoacromegaly condition was established. Data were retrieved from each case and analysed collectively. RESULTS: Of 76 cases, 47 were males, mean ages at presentation and at first acromegaloid symptoms were 28 ± 16 and 17 ± 10 years, respectively. Most common conditions were pachydermoperiostosis (47%) and insulin-mediated pseudoacromegaly (IMP) (24%). Acromegaloid facies (75%) and acral enlargement (80%) were the most common features. Measurement of random GH was reported in 65%, IGF-1 in 79%, OGTT-GH in 51%. GH excess was more frequently excluded based on two tests (53%). Magnetic resonance imaging (MRI) was performed in 30 patients, with pituitary adenoma or hyperplasia being reported in eight and three patients, respectively. Investigations differed between cases managed by endocrine and non-endocrine specialists, the former requesting more often IGF-1, OGTT-GH and pituitary MRI. CONCLUSIONS: Pseudoacromegaly is a challenging entity that may be encountered by endocrinologists. Pachydermoperiostosis and IMP are the conditions most often mimicking acromegaly. Adequate assessment of GH/IGF-1 is crucial to exclude acromegaly, which may be better performed by endocrinologists. Pituitary incidentalomas are common and require careful judgement to prevent unnecessary pituitary surgery.

Bone mineral density, turnover, and microarchitecture assessed by second-generation high-resolution peripheral quantitative computed tomography in patients with Sheehan's syndrome.

Sheehan's syndrome (SS) is a rare but well-characterized cause of hypopituitarism. Data on skeletal health is limited and on microarchitecture is lacking in SS patients. PURPOSE: We aimed to explore skeletal health in SS with bone mineral density (BMD), turnover, and microarchitecture. METHODS: Thirty-five patients with SS on stable replacement therapy for respective hormone deficiencies and 35 age- and BMI-matched controls were recruited. Hormonal profile and bone turnover markers (BTMs) were measured using electrochemiluminescence assay. Areal BMD and trabecular bone score were evaluated using DXA. Bone microarchitecture was assessed using a second-generation high-resolution peripheral quantitative computed tomography. RESULTS: The mean age of the patients was 45.5 ± 9.3 years with a lag of 8.3 ± 7.2 years prior to diagnosis. Patients were on glucocorticoid (94%), levothyroxine (94%), and estrogen-progestin replacement (58%). None had received prior growth hormone (GH) replacement. BTMs (P1NP and CTX) were not significantly different between patients and controls. Osteoporosis (26% vs. 16%, p = 0.01) and osteopenia (52% vs. 39%, p = 0.007) at the lumbar spine and femoral neck (osteoporosis, 23% vs. 10%, p = 0.001; osteopenia, 58% vs. 29%, p = 0.001) were present in greater proportion in SS patients than matched controls. Bone microarchitecture analysis revealed significantly lower cortical volumetric BMD (vBMD) (p = 0.02) at the tibia, with relative preservation of the other parameters. CONCLUSION: Low areal BMD (aBMD) is highly prevalent in SS as compared to age- and BMI-matched controls. However, there were no significant differences in bone microarchitectural measurements, except for tibial cortical vBMD, which was lower in adequately treated SS patients.

Pharmacological and Genetic Disruption of C-Type Natriuretic Peptide (nppcl) Expression in Zebrafish (Danio rerio) Causes Stunted Growth during Development.

Human patients with mutations within NPPC or NPR2 genes (encoding C-type natriuretic peptide (CNP) and guanylyl cyclase-B (GC-B), respectively) display clinical signs associated with skeletal abnormalities, such as overgrowth or short stature. Mice with induced models of Nppc or Npr2 deletion display profound achondroplasia, dwarfism and early death. Recent pharmacological therapies to treat short stature are utilizing long-acting CNP analogues, but the effects of manipulating CNP expression during development remain unknown. Here, we use Danio rerio (zebrafish) as a model for vertebrate development, employing both pharmacological and reverse genetics approaches to alter expression of genes encoding CNP in zebrafish. Four orthologues of CNP were identified in zebrafish, and spatiotemporal expression profiling confirmed their presence during development. Bioinformatic analyses suggested that nppcl is the most likely the orthologue of mammalian CNP. Exogenous CNP treatment of developing zebrafish embryos resulted in impaired growth characteristics, such as body length, head width and eye diameter. This reduced growth was potentially caused by increased apoptosis following CNP treatment. Expression of endogenous nppcl was downregulated in these CNP-treated embryos, suggesting that negative feedback of the CNP system might influence growth during development. CRISPR knock-down of endogenous nppcl in developing zebrafish embryos also resulted in impaired growth characteristics. Collectively, these data suggest that CNP in zebrafish is crucial for normal embryonic development, specifically with regard to growth.

AIP: A double agent? The tissue-specific role of AIP as a tumour suppressor or as an oncogene.

Aryl hydrocarbon receptor-interacting protein (AIP) is a co-chaperone to heat shock proteins and nuclear receptors. Loss-of-function heterozygote germline mutations lead to predisposition to growth hormone- or prolactin-secreting pituitary typically presenting in childhood. Based on these data AIP behaves as a tumour suppressor. However, previously in diffuse large B cell lymphoma and now in this new manuscript in the British Journal of Cancer on colorectal cancer, it seems that high expression of AIP is associated with tumour development and more aggressive disease. AIP, therefore, joins a distinguished group of proteins that can behave both as a tumour suppressor and as an oncogene.

Molecular genetic testing in the management of pituitary disease.

OBJECTIVE: Most pituitary tumours occur sporadically without a genetically identifiable germline abnormality, a small but increasing proportion present with a genetic defect that predisposes to pituitary tumour development, either isolated (e.g., aryl hydrocarbon receptor-interacting protein, AIP) or as part of a tumour-predisposing syndrome (e.g., multiple endocrine neoplasia (MEN) type 1, Carney complex, McCune-Albright syndrome or pituitary tumour and paraganglioma association). Genetic alterations in sporadic pituitary adenomas may include somatic mutations (e.g., GNAS, USP8). In this review, we take a practical approach: which genetic syndromes should be considered in case of different presentation, such as tumour type, family history, age of onset and additional clinical features of the patient. DESIGN: Review of the recent literature in the field of genetics of pituitary tumours. RESULTS: Genetic testing in the management of pituitary disease is recommended in a significant minority of the cases. Understanding the genetic basis of the disease helps to identify patients and at-risk family members, facilitates early diagnosis and therefore better long-term outcome and opens up new pathways leading to tumorigenesis. CONCLUSION: We provide a concise overview of the genetics of pituitary tumours and discuss the current challenges and implications of these genetic findings in clinical practice.

The tumour microenvironment of pituitary neuroendocrine tumours.

The tumour microenvironment (TME) includes a variety of non-neoplastic cells and non-cellular elements such as cytokines, growth factors and enzymes surrounding tumour cells. The TME emerged as a key modulator of tumour initiation, progression and invasion, with extensive data available in many cancers, but little is known in pituitary tumours. However, the understanding of the TME of pituitary tumours has advanced thanks to active research in this field over the last decade. Different immune and stromal cell subpopulations, and several cytokines, growth factors and matrix remodelling enzymes, have been characterised in pituitary tumours. Studying the TME in pituitary tumours may lead to a better understanding of tumourigenic mechanisms, identification of biomarkers useful to predict aggressive disease, and development of novel therapies. This review summarises the current knowledge on the different TME cellular/non-cellular elements in pituitary tumours and provides an overview of their role in tumourigenesis, biological behaviour and clinical outcomes.

Molecular characterization of DICER1-mutated pituitary blastoma.

Pituitary blastoma (PitB) has recently been identified as a rare and potentially lethal pediatric intracranial tumor. All cases that have been studied molecularly possess at least one DICER1 pathogenic variant. Here, we characterized nine pituitary samples, including three fresh frozen PitBs, three normal fetal pituitary glands and three normal postnatal pituitary glands using small-RNA-Seq, RNA-Seq, methylation profiling, whole genome sequencing and Nanostring® miRNA analyses; an extended series of 21 pituitary samples was used for validation purposes. These analyses demonstrated that DICER1 RNase IIIb hotspot mutations in PitBs induced improper processing of miRNA precursors, resulting in aberrant 5p-derived miRNA products and a skewed distribution of miRNAs favoring mature 3p over 5p miRNAs. This led to dysregulation of hundreds of 5p and 3p miRNAs and concomitant dysregulation of numerous mRNA targets. Gene expression analysis revealed PRAME as the most significantly upregulated gene (500-fold increase). PRAME is a member of the Retinoic Acid Receptor (RAR) signaling pathway and in PitBs, the RAR, WNT and NOTCH pathways are dysregulated. Cancer Hallmarks analysis showed that PI3K pathway is activated in the tumors. Whole genome sequencing demonstrated a quiet genome with very few somatic alterations. The comparison of methylation profiles to publicly available data from ~ 3000 other central nervous system tumors revealed that PitBs have a distinct methylation profile compared to all other tumors, including pituitary adenomas. In conclusion, this comprehensive characterization of DICER1-related PitB revealed key molecular underpinnings of PitB and identified pathways that could potentially be exploited in the treatment of this tumor.

AIP variant causing familial prolactinoma.

Pathogenic variants in the aryl hydrocarbon receptor-interacting protein (AIP) gene are increasingly recognised as a cause of familial isolated pituitary adenoma. AIP-associated tumours are most commonly growth hormone (GH) producing. In our cohort of 175 AIP mutation positive patients representing 93 kindreds, 139 (79%) have GH excess, 19 have prolactinoma (17 familial and 2 sporadic cases) and out of the 17 clinically non-functioning tumours 4 were subsequently operated and found to be GH or GH & prolactin immunopositive adenoma. Here we report a family with an AIP variant, in which multiple family members are affected by prolactinoma, but none with GH excess. To our knowledge this is the first reported family with an AIP pathogenic variant to be affected solely by prolactinoma. These data suggest that prolactinoma families represent a small subset of AIP mutation positive kindreds, and similar to young-onset sporadic prolactinomas, AIP screening would be indicated.

Pre-operative serum inflammation-based scores in patients with pituitary adenomas.

OBJECTIVE: Full blood count (FBC) and serum inflammation-based scores reflect systemic inflammation and predict outcomes in cancer, but little is known in pituitary adenomas (PAs). We aimed to characterise FBC and inflammation-based scores in PA patients and investigate their usefulness in predicting challenging disease course. METHODS: We studied 424 PA patients first operated at our centre with available pre-operative biochemical data. Patients with infection, malignancies, autoimmune or haematological conditions were excluded. Inflammation-based scores studied: Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), Lymphocyte-to-Monocyte Ratio (LMR), Systemic Immune-Inflammation Index (SII), Neutrophil-Platelet Score (NPS), Prognostic Nutrition Index (PNI), and Glasgow Prognostic Score (GPS). RESULTS: Cushing's disease patients had more platelets, leucocytes, neutrophils and monocytes, and higher NLR, NPS and SII. Serum inflammation-based scores didn't differ among non-Cushing PA subtypes. The glucocorticoid excess severity influenced leucocyte, eosinophil, basophil and platelet counts, and GPS in Cushing's disease. Patients with functioning non-Cushing PAs with suprasellar extension, cavernous sinus invasion and hypopituitarism had GPS ≥ 1, while NPS ≥ 1 was associated with suprasellar extension. More invasive and difficult to treat corticotrophinomas were associated with fewer platelets pre-operatively (< 299.5 × 109/L predicting multimodal treatment). Non-functioning PA patients who suffered apoplexy had more leucocytes, neutrophils and monocytes, higher GPS ≥ 1 and fewer platelets; re-operated cases had fewer lymphocytes, higher NLR and PLR. CONCLUSIONS: Serum inflammation-based scores may predict invasive/refractory PAs: GPS and PNI in non-functioning and functioning non-Cushing PAs; NPS in functioning non-Cushing PAs; NLR and PLR in non-functioning PAs. Platelets < 299.5 × 109/L predict multimodal treatment in Cushing's disease. Further studies are needed to confirm these observations.

MAFA missense mutation causes familial insulinomatosis and diabetes mellitus.

The ß-cell-enriched MAFA transcription factor plays a central role in regulating glucose-stimulated insulin secretion while also demonstrating oncogenic transformation potential in vitro. No disease-causing MAFA variants have been previously described. We investigated a large pedigree with autosomal dominant inheritance of diabetes mellitus or insulinomatosis, an adult-onset condition of recurrent hyperinsulinemic hypoglycemia caused by multiple insulin-secreting neuroendocrine tumors of the pancreas. Using exome sequencing, we identified a missense MAFA mutation (p.Ser64Phe, c.191C>T) segregating with both phenotypes of insulinomatosis and diabetes. This mutation was also found in a second unrelated family with the same clinical phenotype, while no germline or somatic MAFA mutations were identified in nine patients with sporadic insulinomatosis. In the two families, insulinomatosis presented more frequently in females (eight females/two males) and diabetes more often in males (12 males/four females). Four patients from the index family, including two homozygotes, had a history of congenital cataract and/or glaucoma. The p.Ser64Phe mutation was found to impair phosphorylation within the transactivation domain of MAFA and profoundly increased MAFA protein stability under both high and low glucose concentrations in ß-cell lines. In addition, the transactivation potential of p.Ser64Phe MAFA in ß-cell lines was enhanced compared with wild-type MAFA. In summary, the p.Ser64Phe missense MAFA mutation leads to familial insulinomatosis or diabetes by impacting MAFA protein stability and transactivation ability. The human phenotypes associated with the p.Ser64Phe MAFA missense mutation reflect both the oncogenic capacity of MAFA and its key role in islet ß-cell activity.