Adrenal incidentalomas: experience from a retrospective study in a Chinese population

Clinical Review: The Approach to the Evaluation and Management of Bilateral Adrenal Masses

OBJECTIVE

This white paper provides practical guidance for clinicians encountering bilateral adrenal masses.

METHODS

A case-based approach to the evaluation and management of bilateral adrenal masses. Specific clinical scenarios presented here include cases of bilateral adrenal adenomas, hemorrhage, pheochromocytomas, metastatic disease, myelolipomas, as well as primary bilateral macronodular adrenal hyperplasia.

RESULTS

Bilateral adrenal masses represent approximately 10% to 20% of incidentally discovered adrenal masses. The general approach to the evaluation and management of bilateral adrenal masses follows the same protocol as the evaluation of unilateral adrenal masses, determined based on the patient's clinical history and examination as well as the imaging characteristics of each lesion, whether the lesions could represent a malignancy, demonstrate hormone excess, or possibly represent a familial syndrome. Furthermore, there are features unique to bilateral adrenal masses that must be considered, including the differential diagnosis, the evaluation, and the management depending on the etiology. Therefore, considerations for the optimal imaging modality, treatment (medical vs surgical therapy), and surveillance are included. These recommendations were developed through careful examination of existing published studies as well as expert clinical opinion consensus.

CONCLUSION

The evaluation and management of bilateral adrenal masses require a comprehensive systematic approach which includes the assessment and interpretation of the patient's clinical history, physical examination, dynamic hormone evaluation, and imaging modalities to determine the key radiographic features of each adrenal nodule. In addition, familial syndromes should be considered. Any final treatment options and approaches should always be considered individually.

Demographic and Clinical Characteristics of Patients with Adrenal Incidentaloma from a Single Center in South India: A Retrospective Study

CONTEXT

Adrenal incidentalomas (AIs) are relatively uncommon neoplasms in 2% of apparently healthy individuals requiring evaluation for functionality and malignancy.

AIM

We aimed to study the clinical, biochemical, and radiological profiles of patients presenting with AI and histopathological outcomes of those undergoing adrenalectomy. Materials and Methods: This retrospective study enrolled 62 AI patients attending a tertiary care center in South India between January 2016 and October 2023. Demographic details, radiological features, functionality, and histopathological data were analyzed.

RESULTS

Out of 62 patients, total masses evaluated were 65 indicating bilaterality in 3 patients. The female: male ratio was 1.69, with a median age of 55 years (interquartile range: 44-64 years). 45.1% of individuals were >60 years. The most common indication for imaging was pain abdomen in 43 (69.4%). The median size was 3.2 cm. Fifty-five (88.7%) were assessed for functionality and 27 (49.1%) were functional. Among the 62 individuals, 14 (20.2%) had hypercortisolism, 11 (15.9%) had pheochromocytoma, 5 (7.24%) had primary hyperaldosteronism (PA), and 4 (5.7%) had hyperandrogenism including plurihormonal in 7. A mass size of 3.2 cm was of great value in distinguishing functional tumors with a sensitivity of 72% and specificity of 66% with an area under the curve of 0.682. A total of 34 (54.8%) patients underwent adrenalectomy. On histopathological examination, Adenoma (44.1%) was the most common followed pheochromocytoma (26.5%), adrenal cysts (8.8%), and Myelolipoma (5.9%). Two (5.9%) incidentalomas were adrenocortical carcinoma (ACC). Eight (53.3%) adenomas were functional with 6 having hypercortisolism (including 1 with hyperandrogenism) and 2 with PA.

CONCLUSION

In our experience, the incidence of pheochromocytoma was second most common after adenoma. Since most functional tumors (60%) and all ACCs were ≥4 cm, a thorough biochemical evaluation for hormonal excess and evaluation for malignancy followed by surgery should be considered for lesions, especially ≥4 cm. Thus, we report the baseline demographic and clinical characteristics of patients with AI from a single center in South India.

Management of patients with adrenal myelolipoma: experience from a tertiary referral centre

BACKGROUND

Adrenal myelolipomas are rare, benign, tumours of the adrenal cortex.

AIMS

This study reports the experience of a tertiary adrenal surgery referral centre's approach to the management of patients with adrenal myelolipoma.

METHODS

A retrospective observational cohort study was conducted on all adult patients (> 18 years age) diagnosed with adrenal myelolipoma from January 1, 2014, to December 30, 2022. Demographics, imaging characteristics, histological diagnosis (where applicable) and follow-up data were compared between patients undergoing surgery and those referred to surveillance. Indications for operative intervention were recorded at the time of multidisciplinary team discussion, consisting of surgeons, endocrinology physicians, radiologists, pathologists and specialist nursing representatives.

RESULTS

Of the 522 patients with an adrenal lesion discussed in adrenal tumour meeting between 2014 and 2022, n = 15 (2.8%) were diagnosed with adrenal myelolipoma. Of the 15 patients, 4 underwent adrenalectomy at first presentation (27%), while 1 patient underwent adrenalectomy after interval follow-up. Indications for operative intervention were as follows: 'indeterminate lesion' (n = 3), 'abdominal pain and size (> 4 cm)' (n = 1) and 'mass effect on adjacent organs' (n = 1). The mean rate of lesion growth in patients referred for surveillance (n = 10) was 0.13 cm/year. Histology confirmed adrenal myelolipoma as the diagnosis in all resected tumours.

CONCLUSIONS

For patients with adrenal myelolipoma, the presence of symptoms and/or indeterminate features on imaging may be more clinically useful indications for operative intervention over size alone. The surveillance of adrenal myelolipomas, even in patients with adrenal lesions > 4 cm, is a safe clinical strategy, provided the imaging characteristics are benign and patients remain asymptomatic.

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.

An 8-year clinical experience with diagnosis and treatment of adrenal lesions with calcification

Adrenal lesions with calcification are uncommon and surgical indication remains controversial. We evaluate rational indications for surgical intervention of adrenal lesions with calcification. From 2013 to 2021, 75 adrenal lesions with calcification managed with surgery had necessary studies for evaluation of rational surgical indication. Clinical benefit was defined as relief of symptoms or/and removal of the malignant tumors. Influencing factors for clinical benefit were evaluated by logistic regression. During the past 8-year period, 5057 patients received adrenal surgery in our center and 75 (1.5%) patients were accompanied with calcification, including 34 males and 41 females with a median age of 54 years (IQR = 41-63 years). The median maximum diameter of calcified adrenal lesions on preoperative CT imaging was 4.2 cm (IQR = 3.0-5.9 cm). Clinical benefit was achieved in 22 cases, including 4 cases of malignant tumors and 18 cases of relieved clinical symptoms. Correlation analysis indicated that maximum diameter of the lesion was significantly correlated with clinical benefit (p = 0.025). The maximum diameter in benefit group vs. non-benefit group was 5.5 cm (IQR = 3.7-7.4 cm) vs. 3.7 cm (IQR = 2.8-5.4 cm). AUC of the maximum diameter ROC curve of adrenal lesions was 0.662. The diameter, sensitivity and specificity corresponding to the maximum Youden index value were 4.5 cm, 0.682 and 0.623, respectively. Clinical benefit was not significantly correlated with calcification distribution (peripheral or internally scattered) (P = 0.106), calcification area ≥ 50% (P = 0.617) and internal enhancement of the lesion (P = 0.720). Adrenal lesions with calcification are mostly benign. Clinical benefit is significantly correlated with the maximum diameter of the lesion and 4.5 cm may be considered as the cutoff point of surgical intervention.

Adrenal myelolipomas

Adrenal myelolipomas are benign, lipomatous tumours with elements of myeloid cells, most of which present as adrenal incidentalomas and comprise 3·3-6·5% of all adrenal masses. Adrenal myelolipomas are usually unilateral (in 95% of cases), variable in size, most often found during midlife, and affect both sexes almost equally. On imaging, adrenal myelolipomas show pathognomonic imaging features consistent with the presence of macroscopic fat. Large adrenal myelolipomas can cause symptoms of mass effect, and can occasionally be complicated by haemorrhage. In the event of a concomitant adrenal cortical adenoma or hyperplasia, adrenal hormone excess might be detected in patients with adrenal myelolipoma. Patients with congenital adrenal hyperplasia exhibit a higher prevalence of adrenal myelolipomas than other patient groups, and are at risk of developing large and bilateral lesions. This Review discusses the pathogenesis, clinical presentation, and management of adrenal myelolipomas.

Robotic adrenalectomy in the pediatric population: initial experience case series from a tertiary center

BACKGROUND

Laparoscopic resection is the most well described minimally-invasive approach for adrenalectomy. While it allows for improved cosmesis, faster recovery and decreased length of hospital stay compared with the open approach, instrument articulation limitations can hamper surgical dexterity in pediatric patients. Use of robotic assistance can greatly enhance operative field visualization and instrument control, and is in the early stages of adoption in academic centers for pediatric populations.

CASE PRESENTATION

We present a single-institution series of pediatric adrenalectomy cases. The da Vinci Xi surgical system was used to perform adrenalectomies on three consecutive patients (ages, 2-13 years) at our center. Final pathology revealed ganglioneuroblastoma (n = 2) and pheochromocytoma (n = 1). Median operating time was 244 min (range, 244-265 min); median blood loss was estimated at 100 ml (range, 15-175 ml). Specimens were delivered intact and all margins were negative. Median post-operative hospital stay was 2 days (range, 1-6 days). All patients remain disease-free at median follow-up of 19 months (range, 12-30 months).

CONCLUSION

Our experience continues to evolve, and suggests that robotic surgery is safe, feasible and oncologically effective for resection of adrenal masses in well-selected pediatric patients.

Clinical course of adrenal myelolipoma: A long-term longitudinal follow-up study

OBJECTIVE

We aimed to describe clinical course of myelolipoma and to identify predictors of tumour growth and need for surgery.

DESIGN

A retrospective study.

PATIENTS

Consecutive patients with myelolipoma.

RESULTS

A total of 321 myelolipomas (median size, 2.3 cm) were diagnosed in 305 patients at median age of 63 years (range, 25-87). Median follow-up was 54 months. Most myelolipomas were incidentally detected (86%), whereas 9% were discovered during cancer staging and 5% during workup of mass effect symptoms. Thirty-seven (12%) patients underwent adrenalectomy. Compared to myelolipomas <6 cm, tumours ≥6 cm were more likely to be bilateral (21% vs 3%, P < .0001), cause mass effect symptoms (32% vs 0%, P < .0001), have haemorrhagic changes (14% vs 1%, P < .0001) and undergo adrenalectomy (52% vs 5%, P < .0001). Among patients with ≥6 months of imaging follow-up, median size change was 0 mm (-10, 115) and median growth rate was 0 mm/y (-6, 14). Compared to <1 cm growth, ≥1 cm growth correlated with larger initial size (3.6 vs 2.3 cm, P = .02), haemorrhagic changes (12% vs 2%, P = .007) and adrenalectomy (35% vs 8%, P < .0001).

CONCLUSIONS

Most myelolipomas are incidentally discovered on cross-sectional imaging. Myelolipomas ≥6 are more likely to cause mass effect symptoms, have haemorrhagic changes and undergo resection. Tumour growth ≥1 cm is associated with larger myelolipoma and haemorrhagic changes. Adrenalectomy should be considered in symptomatic patients with large tumours and when there is evidence of haemorrhage or tumour growth.

Adrenal Ganglioneuroma: Features and Outcomes of 42 Cases in a Chinese Population

BACKGROUND

Adrenal ganglioneuromas (AGNs) are extremely rare benign neoplasms. This study is to share our experience regarding diagnostic and operative management of these tumors.

METHODS

Clinical details as well as follow-up data were retrospectively analyzed in 42 primary AGN patients who received operative resection at a tertiary referral hospital in China between May 2005 and July 2016.

RESULTS

The mean age of the patients at diagnosis was 35.3 years (range 13-59 years). Among the patients, 28 were asymptomatic. The mean preoperative size was 5.3 ± 2.2 cm (range 2.1-14.0 cm), and 17 cases were larger than 5 cm. All patients underwent operative resection as open adrenalectomy in 20 patients and laparoscopy in 22 patients. The mean tumor size on pathologic examination was 6.0 ± 2.6 cm (range 2.2-17.0 cm). Laparoscopic operation showed its advantages over open surgery on the postoperative duration (5.0 vs. 7.3 days, p < 0.001) and estimated blood loss (69.5 vs. 157.5 ml, p = 0.047). No patient had recurrence or metastasis during a median follow-up of 70.5 months (range 3.7-164.3 months).

CONCLUSIONS

We describe the largest AGN series reported to date. The preoperative diagnosis of AGN remains difficult despite of the progression of imaging examination. After complete resection, the prognosis of AGN patients is excellent. Laparoscopic approach has its advantages in the resection of AGNs.

Characteristics of Adrenal Incidentalomas in a Large, Prospective Computed Tomography-Based Multicenter Study: The COAR Study in Korea

PURPOSE

Previous studies on adrenal incidentalomas (AIs) are limited by their retrospective design, small numbers of patients, Western populations, or use of an outdated imaging technique. We investigated the characteristics of AIs in Korean patients and compared them with those reported in the largest retrospective study in Italy to discover the effects of improved imaging techniques and ethnicity differences.

MATERIALS AND METHODS

This was a prospective, multicenter, cross-sectional observational study including 1005 Korean patients. Levels of plasma adrenocorticotrophic hormone, 24-h urinary free cortisol (UFC), serum cortisol after a 1 mg-dexamethasone suppression test, 24-h urinary fractionated metanephrine, and plasma aldosterone and plasma renin activity were measured. All AIs were characterized using computed tomography (CT).

RESULTS

Compared with the results of the Italian study, AIs in Korean patients were observed more frequently in men and predominantly on the left side. Korean patients with AIs were slightly younger, and fewer patients underwent surgery. Most AIs were nonfunctional in both studies, while fewer subclinical hypercortisolism and more primary aldosteronism (PA) cases were detected in Korean patients. In our study, high UFC levels showed very low sensitivity, compared to those in the Italian study. In pheochromocytoma or PA cases, there were no hormonal differences between the studies. AIs in Korean patients were smaller, such that a lower cutoff size for detecting adrenocortical carcinoma (ACC) could be warranted.

CONCLUSION

Recent advances in CT technology were leveraged to provide accurate characteristics of AIs and to detect smaller ACCs.

Adrenal myelolipoma: a comprehensive review

INTRODUCTION

Adrenal myelolipoma is an invariably benign neoplasm of the adrenal gland that is the second most common primary adrenal incidentaloma following adrenocortical adenomas. It is composed of elements of adipose tissue and extramedullary hematopoiesis. Hypotheses on stem cells and hormonal factors have been formulated regarding its pathogenesis that is still obscure. Despite its benign behavior, adrenal myelolipoma is clinically relevant as it might cause significant difficulties in the differential diagnosis of adrenal tumors.

METHODS

We have reviewed 420 cases reported between 1957 and 2017 on adrenal myelolipoma retrieved from PubMed and Scopus databases and also 20 of our case series to provide a comprehensive analysis of their pathology, epidemiological and clinical features.

RESULTS AND CONCLUSIONS

The average age for its diagnosis was 51 years, and no gender difference was observed. The average size of tumors was 10.2 cm. Congenital adrenal hyperplasia was associated to 10% of all cases analyzed, while other adrenal hypersecretory disorders (cortisol, aldosterone) were found in 7.5% of cases. Computed tomography and magnetic resonance imaging can be reliably used for its differential diagnosis. If the diagnosis of an adrenal myelolipoma is unambiguous, and no associated symptoms or hormonal activity are established, surgical intervention is usually not necessary.

Clinicopathological Features of Ganglioneuroma Originating From the Adrenal Glands

BACKGROUND

Ganglioneuromas are benign tumors that rarely develop from adrenal glands. In this study, we present our clinical experience of patients with adrenal ganglioneuroma (AGN).

METHODS

Demographic, diagnostic, surgical, and pathologic findings of patients who were adrenalectomized as a result of AGN were retrospectively reviewed from the database of a tertiary referral hospital.

RESULTS

Among 1784 patients who underwent an adrenalectomy between 2002 and 2015, 35 (1.9 %; 14 males, 21 females) were diagnosed with AGN. Mean age was 33.4 ± 18.7 years (0-84). Twenty-nine (82.9 %) were asymptomatic, four (11.4 %) complained of abdominal discomfort, and two (5.7 %) had abdominal distension. Preoperative computed tomography (CT) reported AGN in 22 (62.9 %) cases. Precontrast Hounsfield units, increased postcontrast phase attenuation, and well-defined borders were characteristic CT features of AGN. Mean tumor size was 6.3 ± 3.3 cm (range, 1.5-16.0). No recurrence occurred during a median follow-up period of 19 months (range, 1-120).

CONCLUSION

AGN was asymptomatic in most cases and diagnosis may be challenging. Adrenalectomy is a safe treatment modality for AGN and ensures favorable outcomes when diagnosed.

Baseline Demographic and Clinical Characteristics of Patients with Adrenal Incidentaloma from a Single Center in China: A Survey

AIM

To investigate the clinical and endocrinological characteristics of patients with adrenal incidentaloma (AI).

MATERIALS AND METHODS

This retrospective study enrolled 1941 AI patients hospitalized at the Department of Endocrinology, Chinese PLA General Hospital, Beijing, China, between January 1997 and December 2016. The patient gender, age at visits, imaging features, functional status, and histological results were analyzed.

RESULTS

Of the 1941 patients, 984 (50.70%) were men. The median age was 52 years (interquartile range: 44-69 years). 140 cases had bilateral AI. Endocrine evaluation showed that 1411 (72.69%) patients had nonfunctional tumor, 152 (7.83%) had subclinical Cushing syndrome (SCS), and 82 (4.33%) had primary hyperaldosteronism. A total of 925 patients underwent operation for removal of 496 cortical adenomas (53.62%), 15 adrenal cortical carcinomas (1.62%), and 172 pheochromocytomas (18.59%). The bilateral group had a higher proportion of SCS (18.57% versus 7.10%, P < 0.001, P = 0.006). A mass size of 46 mm was of great value in distinguishing malignant tumors from the benign tumors, with sensitivity of 88.2% and specificity of 95.5%.

CONCLUSIONS

We reported the baseline demographic and clinical characteristics of patients with AI in a large series from a single center in China.

Laparoscopic treatment of adrenal masses in children: Report of two cases and review of literature

Laparoscopic adrenalectomy has become a common alternative to open surgery for the resection of adrenal lesions in adults: The advantages are to provide better exposure of the adrenal gland, diminish soft tissue dissection, decrease morbidity and postoperative pain; however, reporting on the laparoscopic adrenalectomy in paediatric patients has been limited. We present two cases of laparoscopic adrenalectomy performed at our institution in two children, for left adrenal neuroblastoma in a first patient with opsomyoclonus syndrome, and for a right incidentaloma in the second case. According to recent literature, our experience has demonstrated that the laparoscopic adrenalectomy is a feasible procedure in children with small, well-circumscribed adrenal masses: It can be used a safety to treat suspected benign and malignant adrenal masses in children, with minimal morbidity and short hospital stay. The lateral trans-peritoneal approach offers optimal visualisation and good outcomes in terms of minimal discomfort, rapid recovery and excellent cosmesis. However, in the paediatric field, the number of patients is limited, making the learning curve longer.

Adrenal myelolipoma: Controversies in its management

Adrenal myelolipomas (AMLs) are rare, benign neoplasms of the adrenal gland with varied clinical presentations. The rarity of these tumors precludes any case-controlled or randomized study into their management. The available literature is limited to case reports and short series from referral centers. This review is an effort to put the available literature into perspective such that clinical decision making can be done with some clarity. The PubMed and Cochrane databases were searched with key words Adrenal Myelolipoma, Adrenal Incidentaloma (AI) and Adrenal Collision Tumor (ACT). From over 1300 search results, 547 relevant publications dating from 1954 to 2014 were reviewed. Details of about 1231 AMLs in the indexed literature were analyzed. Increasing usage of imaging studies has significantly increased the discovery of AMLs. Although AMLs are benign tumors, those measuring larger than 6 cm are prone to rupture and hemorrhage. Thorough endocrine work-up may benefit a selected group of patients, especially those who are hypertensive, diabetic/pre-diabetic, young patients (<50 years) and those with bilateral AML. Regular observation is needed for AML patients who are being treated non-operatively, as many of them may require surgery during follow-up. Although the AACE/AAES guidelines for AI (2009) exclude AML from mandatory metabolic work-up for a newly discovered AI, we feel that a significant number of patients with AML would benefit from metabolic work-up. In the literature, endocrine dysfunction in AML is 7% as compared with 11% in AI. Endocrine dysfunction in AML is probably underdiagnosed.

Adrenal incidentalomas: should we operate on small tumors in the era of laparoscopy?

Tumor size smaller than 4 cm as an indication for surgical treatment of incidentaloma is still a subject of discussion. Our aim was the estimation of the incidence of malignancy and analysis of treatment outcomes in patients with incidentaloma smaller than 4 cm in comparison to bigger lesions. 132 patients who underwent laparoscopic adrenalectomy for nonsecreting tumors were divided into two groups: group 1 (55 pts., size < = 40 mm) and group 2 (77 pts., size > 40 mm). Operation parameters and histopathological results were analyzed. No differences in group characteristics, mean operation time, and estimated blood loss were noted. Complications in groups 1 and 2 occurred in 3.6% and 5.2% of patients, respectively (P = 0.67). Malignancy in groups 1 and 2 was present in 1 and 6 patients, respectively (P = 0.13). Potentially malignant lesions were identified in 4 patients in group 1 and 4 patients in group 2 (P = 0.39). The results do not allow for straightforward recommendations for surgical treatment of smaller adrenal tumors. The safety of laparoscopy and minimal, but impossible to omit, risk of malignancy support decisions for surgery. On the other hand, the risk of malignancy in smaller adrenal tumors is lower than surgical complications, which provides an important argument against surgery.

Risk of concomitant malignancy in hyperfunctioning adrenal incidentalomas

BACKGROUND

Adrenal masses are common incidental findings on radiologic imaging. The association between malignancy and hormonal hyperactivity found in incidentally discovered adrenal tumors, however, remains unclear.

METHODS

A retrospective analysis of prospectively collected data from patients who underwent adrenalectomy for incidentally discovered adrenal tumors at a single institution. Outcomes and operative data were compared by univariate analysis. Area under the curve was used to analyze the effect of tumor size in predicting malignancy.

RESULTS

There were 49 patients who initially presented with adrenal incidentalomas that underwent adrenalectomy. Most patients were Caucasian women with an average age of 51 ± 14 years. Of this group, 24 patients underwent resection for hyperfunctioning adrenal glands. There were no significant differences in malignancy rates between hyperfunctional and nonfunctional tumors (4.1% vs. 12.0%, P = 0.32). On final histopathology, there were four patients with adrenal malignancies: two adrenocortical carcinomas and two metastatic from renal carcinoma. Only one patient with a hyperfunctioning adrenal tumor had underlying malignancy. Overall, invasion of adjacent structures (P < 0.001), presence of lymphadenopathy (P = 0.02), metastasis (P = 0.03), irregular tumor margins (P = 0.01), heterogeneity (P = 0.05), and tumor size >6 cm (P = 0.04) on radiologic imaging were strongly associated with malignancy in adrenal incidentalomas.

CONCLUSIONS

The risk of concomitant malignancy and hormonal hyperactivity in adrenal incidentalomas is very low. Tumor size (>6 cm) and radiographic features remain the most important predictors of adrenal malignancy, regardless of tumor function.