Skeletal Muscle Evaluation in Patients With Acromegaly

Context

Patients with acromegaly are characterized by chronic exposure to high growth hormone (GH) and insulin-like growth factor-1 levels, known for their anabolic effect on skeletal muscle. Therefore, an increased skeletal muscle mass could be hypothesized in these individuals. Herein, we have performed a systematic revision of published evidence regarding skeletal muscle mass, quality, and performance in patients with acromegaly.

Evidence Acquisition

A systematic review of the literature in the PubMed database up to September 1, 2023, was conducted with the following query: acromegaly AND ("muscle mass" OR "skeletal muscle"). We excluded studies that did not compare different disease states or used nonradiological methods for the skeletal muscle analyses, except for bioelectrical impedance analysis.

Evidence Synthesis

Fifteen studies met the inclusion criteria. A total of 360 patients were evaluated for skeletal muscle mass, 122 for muscle fatty atrophy, and 192 for muscle performance. No clear evidence of increased skeletal muscle mass in patients with active disease compared to control or healthy individuals emerged. As for skeletal muscle quality, we observed a trend toward higher fatty infiltration among patients with acromegaly compared to healthy participants. Likewise, patients with active disease showed consistently worse physical performance compared to control or healthy individuals.

Conclusion

Skeletal muscle in acromegaly has lower quality and performance compared to that of healthy individuals. The small number of published studies and multiple confounding factors (eg, use of different radiological techniques) contributed to mixed results, especially regarding skeletal muscle mass. Well-designed prospective studies are needed to investigate skeletal muscle mass in patients with acromegaly.

Long-term, real-world experience of pasireotide dose reduction in patients with acromegaly

Pasireotide long-acting release is effective in achieving biochemical control and reducing tumour volume in patients with acromegaly inadequately controlled by first-line therapy. As part of a long-term, real-world study at our centre, 20 of 50 patients receiving pasireotide benefited from a reduction in pasireotide dose. Pasireotide reduced insulin-like growth factor I (IGF-I) levels to below the upper limit of the normal range, with some patients responding within 1-3 months of treatment (n=11) and others after ≥4 months (n=9). Following pasireotide dose reduction, IGF-I levels showed a mild increase but remained within the normal range after a median of 39 months in the early responders and 17 months in the late responders. Glucose and glycated haemoglobin levels decreased following dose reduction. Identifying patients who may benefit from a reduction in pasireotide dose warrants further research as it may improve the management of pasireotide-associated hyperglycaemia in susceptible patients.

USP8 Somatic Mutations in Cushing’s Disease and Silent Corticotropinomas

Background: Somatic mutations in the ubiquitin-specific peptidase 8 (USP8) gene have been described in Cushing’s disease (CD). These mutations increase proopiomelanocortin transcription resulting in ACTH production and seem to correlate with somatostatin receptor type 5 (SST5) expression. Aims: Screen USP8 in patients with corticotropinomas and correlate USP8 mutational status with SST5 expression in CD. Methods: Tumor DNA was extracted and then exon 14 amplified by PCR. SST5 was assessed by immunohistochemistry (clone UMB4) and quantified multiplying the percentage of positive cells (0,0%; <10%,1;10-50%, 2; 51-80%, 3; >80%, 4) and intensity (mild, 1; moderate, 2; intense, 3), giving a score (IRS) from 0-12 with ≥ 6 considered high. Results: Among 59 patients, 38 had CD and 21 silent corticotropinomas. In CD, 13 (34.2%) patients had pathogenic mutations (6 had p.Ser719del; 5 had p.Pro720Arg and 2 had p.Pro720Gln). In the mutated CD group, all were women and had median age of 34.5 years (20-46). Median ACTH was 64.7pg/mL [(34.8-330.0), normal <46], urinary free cortisol (UFC) 435.0μg/24h [(87.0-1386.0), normal <100], cortisol after overnight 1mg dexamethasone suppression test (ODST) 17.4μg/dL [(5.0-48.7), normal <1.8], salivary cortisol (SC) 8.1μg/dL [(1.0-15.5), normal <0.35]. Median largest tumor size was 0.9 cm (0-1.9), ki-67 1.7 (0.2-10.0) and IRS 12 (1-12). In wild-type CD group, 19 (76.0%) were women and had median age was 35.0 years old (14-62). Median ACTH was 59.7 (39.0-137.0), UFC 305.8 (77.0-1302.0), cortisol after ODST 23.6 (10.0-33.3), SC 0.67 (0.27-1.28). Median largest tumor diameter 0.7cm (0-3.3), ki-67 1.8 (0.2-10) and IRS 4 (0-12). SC was higher in mutated group compared to wild-type (p=0.001) as well as IRS (p=0.009). In silent corticotropinomas, 2 (9.5%) had pathogenic mutations (1 p.Ser718Pro and 1 p.Pro720Arg): male, 36 years old, 3.2 cm tumor, Ki-67 4%, IRS 6; and female, 52 years old, 3.4 cm tumor, Ki-67 2.5%, IRS 12, respectively. One tumor had a variant not reported as pathogenic (p.Thr739Ala): male, 46 years old, 3.7 cm tumor, Ki-67 0.5%, IRS 0. USP8-wild-type silent corticotropinomas had IRS 0-2. Conclusion: One third of CD patients presented with somatic USP8 mutation. Similar to another study, about 10% of silent corticotropinomas also presented somatic USP8 mutation. Expression of SST5 was high in USP8-mutated CD and higher than wild-type group.

Apoplexy in sporadic pituitary adenomas: a single referral center experience and AIP mutation analysis

Objective

To analyze the clinical, laboratory, and radiological findings and management of patients with clinical pituitary apoplexy and to screen for aryl hydrocarbon receptor-interacting protein (AIP) mutations.

Methods

The clinical findings were collected from the medical records of consecutive sporadic pituitary adenoma patients with clinical apoplexy. Possible precipitating factors, laboratory data, magnetic resonance imaging (MRI) findings and treatment were also analyzed. Peripheral blood samples were obtained for DNA extraction from leukocytes, and the entire AIP coding region was sequenced.

Results

Thirty-five patients with pituitary adenoma were included, and 23 (67%) had non-functioning pituitary adenomas. Headache was observed in 31 (89%) patients. No clear precipitating factor was identified. Hypopituitarism was observed in 14 (40%) patients. MRI from 20 patients was analyzed, and 10 (50%) maintained a hyperintense signal in MRI performed more than three weeks after pituitary apoplexy (PA). Surgery was performed in ten (28%) patients, and 25 (72%) were treated conservatively with good outcomes. No AIP mutation was found in this cohort.

Conclusion

Patients with stable neuroophthalmological impairments can be treated conservatively if no significant visual loss is present. Our radiological findings suggest that hematoma absorption lasts more than that observed in other parts of the brain. Additionally, our study suggests no benefits of AIP mutation screening in sporadic patients with apoplexy.

Experience with pegvisomant treatment in acromegaly in a single Brazilian tertiary reference center: efficacy, safety and predictors of response

Objective

To describe the safety and efficacy of pegvisomant therapy and the predictors of treatment response in acromegaly patients at a single tertiary reference center in Brazil.

Materials and methods

We retrospectively reviewed the clinical, hormonal and radiological data of acromegaly patients treated with pegvisomant in our center. We also evaluated the presence of the d3 isoform of the growth hormone receptor (d3GHR).

Results

Twenty-seven patients were included (17 women). Pegvisomant was used in combination with octreotide LAR in 20 patients (74%), in combination with cabergoline in one (4%) and as monotherapy in six (22%). IGF-I normalization was achieved in 23 patients (85%). Mild and transitory elevation of liver enzymes was observed in two patients (7.4%), tumor growth in one (3.4%) and lipodystrophy in two (7.4%). One patient stopped the drug due to headaches. The GHR isoforms were evaluated in 14 patients, and the presence of at least one d3GHR allele was observed in 43% of them, but it was not a predictor of treatment response. Only pre-treatment IGF-I level was a predictor of treatment response.

Conclusion

Pegvisomant treatment was highly effective and safe in our series of Brazilian patients. A better chance of disease control can be expected in those with lower pre-pegvisomant IGF-I levels.

Ki-67 is a predictor of acromegaly control with octreotide LAR independent of SSTR2 status and relates to cytokeratin pattern

INTRODUCTION

Only one study has evaluated Ki-67 as a predictor of the response to somatostatin analog therapy in acromegaly; however, other predictors like somatostatin receptor type 2 (SSTR2) and cytokeratin pattern expressions were not considered.

OBJECTIVE

To evaluate whether Ki-67 is a predictor of octreotide LAR (OCT-LAR) response in somatotropinomas independent of SSTR2 and cytokeratin expression patterns.

METHODS

Protein expression was analyzed by immunohistochemistry. The percentage of cell nuclei that were immunolabeled for Ki-67 and the percentage of cells with positive SSTR2 staining were calculated. SSTR2 expression was considered high when ≥25%, and a cutoff of 2.3% was designated for Ki-67. Tumors were classified as densely or sparsely granulated according to the cytokeratin pattern.

RESULTS

Thirty-one somatotropinomas were studied. Fourteen patients (45.2%) were controlled with OCT-LAR therapy. The median Ki-67 labeling index (LI) was higher in patients not controlled with OCT-LAR than in those controlled (1.63 and 0.15 respectively, P=0.002). Higher SSTR2 expression and densely granulated tumors were correlated with control as well (P=0.04 and 0.038 respectively). There was no difference in Ki-67 levels between patients with high and low SSTR2 expression (P=0.651). After multivariate analysis, both Ki-67 and SSTR2 remained statistically significant as predictors of OCT-LAR response (P=0.017 and 0.012 respectively). The Ki-67 LI was higher in sparsely than in densely granulated tumors (P=0.047).

CONCLUSIONS

Ki-67 is a predictor of response to OCT-LAR in acromegaly, independent of SSTR2 expression and relates to cytokeratin patterns.

Association of dengue hemorrhagic fever with multiple risk factors for pituitary apoplexy

OBJECTIVE

To describe pituitary apoplexy that developed during the course of dengue hemorrhagic fever.

METHODS

We describe the clinical findings, laboratory test results, imaging findings, and clinical course of the study patients.

RESULTS

Patient 1 was a 40-year-old man who developed clinical signs and symptoms of dengue, which was confirmed by serologic testing. He presented with thrombocytopenia and developed severe headache and vomiting. During hospitalization, acromegaly was suspected because of the characteristic disease phenotype. Magnetic resonance imaging confirmed the diagnosis of pituitary apoplexy. Subsequently, the biochemical diagnosis of acromegaly was confirmed, and the patient underwent transsphenoidal surgery. Histopathologic examination showed signs of recent bleeding. Patient 2 was a 38-year-old man with a macroprolactinoma, who had been treated with cabergoline for 10 weeks and had shown improvement on laboratory testing and imaging. The patient then presented with clinical symptoms of dengue (confirmed serologically) and thrombocytopenia. He developed bilateral hemianopsia, and magnetic resonance imaging showed enlargement of the pituitary adenoma with signs of intratumoral bleeding. The patient underwent transsphenoidal surgery, and histopathologic examination documented a pituitary adenoma diffusely infiltrated by blood cells.

CONCLUSIONS

We describe dengue as a probable novel condition for pituitary apoplexy because it may be associated with multiple risk factors for pituitary infarction or bleeding. Physicians should suspect pituitary apoplexy in patients with dengue hemorrhagic fever who develop a rapid onset of severe headache and vision defects, even in those without known pituitary adenomas.

Low somatostatin receptor subtype 2, but not dopamine receptor subtype 2 expression predicts the lack of biochemical response of somatotropinomas to treatment with somatostatin analogs

OBJECTIVES

To evaluate somatostatin receptor 2A (SSTR2A) and dopamine receptor 2 (DR2) protein expression in somatotropinomas and to relate it to response to somatostatin analogues (SA).

DESIGN AND PATIENTS

SSTR2A and DR2 expression was analyzed by immunohistochemistry in 88 somatotropinomas from patients submitted to either pre-surgical or adjuvant SA treatment. Tumors were scored according to percentage of immunostained cells: 0 (< 25%), 1 (25-50%), and 2 (> 50%). Relation between protein expression and response to SA was performed in 66 patients. Response to SA was assessed by percent IGF-I reduction, being considered as an IGF-I per cent reduction higher than 50%. Disease control was also assessed (GH < 1.0 ng/ml and normal IGF-I).

RESULTS

SSTR2A and DR2 were expressed in 100% and 98% of tumors, respectively. Biochemical response and disease control rates were 48% and 32%, respectively. Median IGF-I percent reduction after 3 months of SA treatment was lower in the SSTR2A score 0 than in the scores 1 and 2 (p < 0.001, both), and after 6 months in the score 0 than in the score 1 (p = 0.001) and 2 (p < 0.001). Biochemical response and disease control were associated with SSTR2 expression (p < 0.001 and p = 0.004, respectively). A negative predictive value for biochemical response of 100% was found when a SSTR2A expression < 25%of immunostained cells cut-off point was considered. No relation was found between DR2 expression and biochemical response and disease control.

CONCLUSION

SSTR2A and DR2 are highly expressed in somatotropinomas. Low SSTR2A, but not DR2, expression is a negative predictive factor to response to SA.

Validation of immunohistochemistry for somatostatin receptor subtype 2A in human somatotropinomas: comparison between quantitative real time RT-PCR and immunohistochemistry

Somatostatin receptors subtype 2 (SSTR2) expression in somatotropinomas is recognized as a predictor of response to the currently available somatostatin analogs and may be analyzed, mainly, by quantitative RT-PCR or immunohistochemistry (IHC). The former has the advantages of a higher sensitivity and of being quantitative, while the latter, although semi-quantitative, evaluates protein expression and is routinely used in the evaluation of pituitary adenomas. We aimed to evaluate the SSTR2A protein expression in somatotropinomas and to compare it to our previous data regarding mRNA expression, assessed by quantitative real time RTPCR. Thirteen somatotropinomas were analyzed by IHC and the tumors were scored according to percent of immunostained cells: 0 (<25%), 1 (25-50%) and 2 (>50%). SSTR2A immunostaining was present in all but one somatotropinoma, 4 (31%) tumors were classified as score 0, 4 (31%) as score 1, and 5 (38%) as score 2. Median SSTR2 mRNA content was significantly different among the three IHC scores (p=0.036) and was lower in the score 0 than in the score 2 (p=0.016). The finding that there is a positive correlation between RT-PCR and IHC indicates that IHC can be applied in order to assess the SSTR2A content in somatotropinomas.

Sellar and suprasellar mixed germ cell tumor mimicking a pituitary adenoma

Germ cell tumors (GCT) are a heterogeneous group of lesions whose origin is not well established. Several cases of primary intrasellar germinomas have been reported, however non-germinomatous GCT have rarely been described. We report the case of a young adult male patient with a mixed GCT that presented with a sellar tumor with suprasellar extension. The patient seeked medical attention because of seizures and magnetic resonance imaging evidenced a tumor of the sellar region. Hyperprolactinemia was also present and dopamine agonist therapy was started. As there was a rapid tumor growth and the patient had concomitant central diabetes insipidus and elevated testosterone levels, a GCT was suspected and confirmed by elevated serum concentration of β-human chorionic gonadotrophin. Patient underwent surgical resection of the tumor and histopathological examination confirmed the diagnosis of a mixed GCT. Chemotherapy was initiated, followed by conventional radiotherapy. In conclusion, although pituitary adenomas respond for the vast majority of sellar tumors, concomitant symptoms such as central diabetes insipidus and rapid tumor growth should raise the suspicion of a diverse diagnosis. The present report intend not only to show a rare case of sellar and suprasellar mixed GCT but also to remind clinicians that if laboratory findings do not fit into patient's diagnosis (such as high testosterone levels in our patient), then the diagnosis should be reviewed.

Familial isolated pituitary adenomas experience at a single center: clinical importance of AIP mutation screening

We present four FIPA kindred discussing clinical and molecular data and emphasizing the differences regarding AIP status, as well as the importance of genetic screening. Family 1 consists of five patients harboring somatotropinomas with germline E24X mutation in AIP. In one of the patients, acromegaly was diagnosed through active screening, being cured by surgery. Families 2 and 3 are composed of two patients with non-functioning pituitary adenomas. Family 4 comprises patients harboring a prolactinoma and a somatotropinoma. No mutations in AIP were found in these families. No patient in Family 1 was controlled with octreotide treatment, while the acromegalic patient in Family 4 was controlled with octreotide LAR. In conclusion, FIPA is a heterogeneous condition, which may be associated with AIP mutation. Genomic and clinical screening is recommended in families with two or more members harboring pituitary adenomas, allowing early diagnosis and better outcome.

Low aryl hydrocarbon receptor-interacting protein expression is a better marker of invasiveness in somatotropinomas than Ki-67 and p53

BACKGROUND

Some pituitary adenomas exhibit fast growth and invade surrounding structures. To date, there is no robust marker to predict invasiveness.

AIM

To evaluate Ki-67, p53 and aryl hydrocarbon receptor-interacting protein (AIP) expression and compare these between invasive and noninvasive somatotropinomas and nonfunctioning pituitary adenomas (NFPAs).

METHODS

Protein expression was determined by immunohistochemistry. Tumors were classified according to percentage of immunolabeled nuclei for Ki-67 and p53. AIP immunopositivity was graded according to a score encompassing pattern and intensity. Invasiveness was defined according to radiological and surgical criteria.

RESULTS

Thirty-eight sporadic somatotropinomas were studied. Median Ki-67 labeling index in invasive and noninvasive tumors was 1.6 (range 0-20.6) and 0.26 (0-2.2), respectively (p = 0.01). With a 2.3% cut-off point obtained by ROC curve analysis, invasive adenomas were distinguished with 100% specificity, 39% sensitivity, and 63% accuracy. Low AIP expression was also correlated with tumor invasiveness (p = 0.001), with sensitivity, specificity and accuracy of 78, 80, and 79%, respectively. Expression of p53 was not different among tumors. Twenty-nine NFPAs were studied, with no significant difference between Ki-67, p53 and AIP expression in invasive and noninvasive tumors. High AIP expression was more frequent in NFPAs, with Ki-67 >3% (p = 0.051), especially when only gonadotrope cell adenomas (n = 25) were considered (p = 0.012).

CONCLUSIONS

These data suggest, for the first time, that AIP is a better marker of invasiveness in somatotropinomas than Ki-67 and p53. In addition, low AIP expression is observed in invasive somatotropinomas, in contrast with high AIP expression in NFPAs (mainly gonadotrope cell tumors) with high proliferative indices.

Utility of [(18)F] fluoro-2-deoxy-D: -glucose positron emission tomography in the localization of ectopic ACTH-secreting tumors

Ectopically ACTH producing tumors may be difficult to localize by conventional radiology and functional imaging may be helpful. Case 1: 31-year-old man was diagnosed with ectopic ACTH-dependent Cushing's syndrome (ECS). Thorax CT revealed a 1.3 cm nodular opacity in upper left lobe, suggestive of residual lesion. [(18)F] fluoro-2-deoxy-D: -glucose ([(18)F] FDG) positron emission tomography ([(18)F] FDG PET) scan revealed mild glycolytic metabolic activity. Pathological examination confirmed an ACTH-positive carcinoid tumor. Case 2: 53-year-old woman presented with very rapid onset ECS. Pituitary MRI was normal. Thorax CT revealed no tumoral lesion. Abdominal and pelvic MRI showed images suggestive of hepatic and iliac, femoral and lumbar secondary implants. [(18)F] FDG PET scan revealed intense uptake in uterus, especially cervix, suggesting this to be the primary tumor site. These cases illustrate the role of [(18)F] FDG PET in the investigation of an ECS where conventional imaging studies were not elucidative in the search for a responsible tumor.