Likelihood ratio of computed tomography characteristics for diagnosis of malignancy in adrenal incidentaloma: systematic review and meta-analysis

Impact of Size Thresholds on the Diagnosis of Incidental Adrenal Lesions: A Systematic Review and Meta-Analysis

BACKGROUND

Preferred size-threshold recommendations for management of incidental adrenal lesions remain controversial.

PURPOSE

This meta-analysis aimed to compare the diagnostic accuracy of different size thresholds for detecting malignancy in patients with incidental adrenal lesions on imaging.

MATERIALS AND METHODS

A systematic review of MEDLINE, Embase, Scopus, the Cochrane Library, and the gray literature, covering the period from inception to September 2021, was performed. Studies with >10 patients evaluating the diagnostic accuracy of imaging size thresholds for detecting malignancy in patients with incidental adrenal lesions and no prior history of cancer were included. Study, clinical, imaging, and accuracy data for eligible studies were independently acquired by two reviewers. Primary meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool.

RESULTS

From 2,690 citations, 40 studies (9,794 patients with mean age ranging from 41 to 66 years) were included. Most (36 of 40) were retrospective single-center studies. CT with or without MRI served as the index test(s). Sensitivity and specificity values, respectively, by size threshold used in the included studies were as follows: 85% (95% confidence interval [CI] 74%-91%) and 39% (95% CI 23%-57%) for 3-cm thresholds; 85% (95% CI 78%-90%) and 75% (95% CI 62%-85%) for 4-cm thresholds; 70% (95% CI 56%-81%) and 74% (95% CI 59%-85%) for 5-cm thresholds; and 75% (95% CI 67%-82%) and 77% (95% CI 62%-87%) for 6-cm thresholds. No cause for variability in sensitivity or specificity was identified on subgroup analysis of the 4-cm threshold. Nearly half of the studies (19 of 40) had at least one QUADAS-2 domain with a high risk of bias.

CONCLUSIONS

A 4-cm size threshold demonstrates the highest combined sensitivity and specificity, with a preserved specificity compared with higher size thresholds, but with a trend toward improved sensitivity. Future research reevaluating 4-5 cm size thresholds while excluding characteristically benign lesions by imaging may help redefine a size threshold that has improved specificity but preserved sensitivity, compared with the existing 4-cm threshold.

[Neurofibromatosis type 1 associated with pheochromocytoma: a case report with a brief review of the literature]

We presented the clinical case of neurofibromatosis type 1 (NF-1) associated with pheochromocytoma (PHEO) in a man under 40 years old without family history. The diagnosis of NF-1 was established based on 4 signs of the disease (multiple café au lait macules, scoliotic changes in posture, the presence of multiple neurofibromas, Lisch nodules). The diagnosis of PHEO was determined by a significant increase of free metanephrin/normethanephrin levels in daily urine, a malignant CT phenotype of the right adrenal tumor, and confirmed by pathomorphological study. Genetic tests revealed a new mutation in one of the alleles of NF1 gene, a deletion of a 566 bp gene fragment, including exon 19 with a size of 73 bp. This mutation leads to splicing of exons 18 and 20, frameshift, and termination of protein synthesis. A study of the level of transcription of the genes associated with PHEO (RET, TMEM127, MAX, FGFR, MET, MERTK, BRAF, NGFR, Pi3, AKT, MTOR, KRAS, MAPK) was conducted, a statistically significant decrease in the level of transcription of the KRAS and BRAF genes and increase in the level of transcription of the TMEM127 gene in comparison with control samples have been detected. This case demonstrates the need for timely recognition of NF-1 for further appropriate patient's follow up and show the effectiveness of a multidisciplinary approach to the diagnosis and treatment of NF-1-associated catecholamine-secreting tumors.

Stereotactic radiotherapy for adrenal oligometastases

Approximately 50% of melanomas, 30–40% of lung and breast cancers and 10–20% of renal and gastrointestinal tumors metastasize to the adrenal gland.

Metastatic adrenal involvement is diagnosed by computed tomography (CT ) with contrast medium, ultrasound (which does not explore the left adrenal gland well), magnetic resonance imaging (MRI) with contrast medium and 18F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDGPET-CT ) which also evaluates lesion uptake. The simulation CT should be performed with contrast medium; an oral bolus of contrast medium is useful, given adrenal gland proximity to the duodenum. The simulation CT may be merged with PET-CT images with ¹⁸FDG in order to evaluate uptaking areas. In contouring, the radiologically visible and/or uptaking lesion provides the gross tumor volume (GTV ). Appropriate techniques are needed to overcome target motion. Single fraction stereotactic radiotherapy (SRT ) with median doses of 16–23 Gy is rarely used. More common are doses of 25–48 Gy in 3–10 fractions although 3 or 5 fractions are preferred. Local control at 1 and 2 years ranges from 44 to 100% and from 27 to 100%, respectively. The local control rate is as high as 90%, remaining stable during follow-up when BED_10Gy is equal to or greater than 100 Gy. SRT-related toxicity is mild, consisting mainly of gastrointestinal disorders, local pain and fatigue. Adrenal insufficiency is rare.

Attenuation Value in Adrenal Incidentalomas: A Longitudinal Study

Context

A tendency to grow has been reported in adrenal incidentalomas. However, long-term data regarding attenuation value, a measure of lipid content, are not available.

Aim

This study aims to collect radiological data (diameter in mm and attenuation value in Hounsfield units, HU) with computed tomography (CT) in adrenal incidentalomas, in order to compare baseline characteristics with the last follow-up imaging.

Design

This is a longitudinal study which included patients with a new diagnosis of adrenal incidentaloma, evaluated from January 2002 to June 2020.

Setting

Referral University-Hospital center.

Patients

Two hundred seventy-seven patients with 355 different cortical adenomas (baseline group) were evaluated at the first outpatient visit; the follow-up cohort consists of 181 patients with 234 adenomas (12-175 months after baseline). Inclusion criteria were conservative management and radiological features able to minimize malignancy or risk of progression.

Main Outcome Measure

CT modification according to endocrine function: autonomous cortisol secretion (ACS) if cortisol >50 nmol/L after 1-mg dexamethasone test (DST).

Results

At baseline CT, mean diameter was 18.7 mm and attenuation value was 0.8 HU (higher in ACS, 66 cases >10 HU), without modification in early imaging (12-36 months). The size increased over time (r = 0.289), achieving the largest differences after at least 60 months of follow-up (mean diameter, +2 mm; attenuation value, -4 HU), combined with a reduction in the attenuation value (r = -0.195, especially in patients with ACS). Lipid-poor adenomas (>10 HU) presented a reduced cortisol suppression after 1-mg DST, an increase in size and the largest decrease in attenuation value during follow-up. Univariate analysis confirmed that larger adenomas presented reduced suppression after DST and increase in size during follow-up.

Conclusions

Growth is clinically modest in adrenal incidentaloma: the first follow-up CT 5 years after baseline is a reasonable choice, especially in ACS. Mean density is increased in patients with ACS and overt hypercortisolism. Mean density reduces during follow-up in all adrenal adenomas, suggesting an increase in lipid content, especially in those with ACS.

Draft of the clinical practice guidelines “Adrenal incidentaloma”

The wider application and technical improvement of abdominal imaging procedures in recent years has led to an increasingly frequent detection of adrenal gland masses — adrenal incidentaloma, which have become a common clinical problem and need to be investigated for evidence of hormonal hypersecretion and/or malignancy. Clinical guidelines are the main working tool of a practicing physician. Laconic, structured information about a specific nosology, methods of its diagnosis and treatment, based on the principles of evidence-based medicine, make it possible to give answers to questions in a short time, to achieve maximum efficiency and personalization of treatment. These clinical guidelines include data on the prevalence, etiology, radiological features and assessment of hormonal status of adrenal incidentalomas. In addition, this clinical practice guideline provides information on indications for surgery, postoperative rehabilitation and follow-up.

WFUMB position paper on the management incidental findings: adrenal incidentaloma

Focal lesions of the adrenal glands are incidentally detected in approximately 5% of cases by modern imaging techniques. Fewer than 5% of these adrenal incidentalomas are malignant and approximately 10% have endocrine activity. Reliable differentiation of malignant versus benign and hormonally active versus nonfunctional adrenal incidentalomas significantly influences therapeutic management and the outcome of affected individuals. Therefore, each adrenal incidentaloma should undergo a standardized diagnostic work-up to exclude malignancy and endocrine activity. This position statement of the World Federation of Ultrasound in Medicine and Biology (WFUMB) summarizes the available evidence on the management of adrenal incidentaloma and describes efficient management strategies with particular reference to the role of ultrasound techniques.