Assessment of Adrenal Cortical Neoplasms for the GU Pathologist
Rumeal D. Whaley, MD, Sounak Gupta, MBBS, PhD, and Lori A. Erickson, MD
Abstract: The challenging aspect of adrenal gland pathology is that adrenal cortical carcinoma is rare but is in the differential for every adrenal gland biopsy and adrenalectomy specimen. Currently, the Weiss system (for adult patients) and Wieneke criteria (for pedia- tric patients) remain the most widely used for diagnostic adrenal cortical pathology. More recent multiparameter systems have been developed, including those using different parameters and schemes for specific scenarios. Even so, there are caveats with each multi- parameter scoring system. Also, if Ki-67 is not performed as part of a multiparameter scoring system, it should be performed as it has clinical significance in all age groups. The “eyeballing” method of interpretation of Ki-67 is discouraged. The increased under- standing of the genomic landscape of adrenal cortical neoplasia may allow for better risk stratification, therapeutics, and monitoring.
Key Words: adrenal cortical carcinoma, adrenocortical carcinoma, Weiss, Helsinki, reticulin algorithm
(Adv Anat Pathol 2026;33:117-128)
T he evaluation and prognostication of adrenal cortical tumors continue to evolve. The 1984 criteria and the updated 1989 criteria provided by Dr. Weiss remain the standard for distinguishing adrenal cortical carcinomas from adenomas.1,2 In the years since the original Weiss criteria other multiparameter systems have been developed, includ- ing those using different parameters and schemes, including those for specific tumor features such as oncocytic adrenal cortical neoplasms and pediatric adrenal cortical neoplasms.1-7 In a survey of 128 genitourinary pathologists, 20% reported feeling either uncomfortable or very uncom- fortable with adrenal specimens, and 74% strongly endorsed they should be handled by an endocrine pathologist resulting
From the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN.
All authors contributed to the review conception and design. Material preparation, data collection and analysis were performed by R.D.W. and L.A.E. The first draft of the manuscript was written by R.D.W. and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
The data that supports the findings of this study are available from the corresponding author upon reasonable request.
L.E. is on the editorial board of Advances of Anatomic Pathology, but she had no involvement in the peer review of this article and had no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to another journal editor. The remaining authors have no funding or conflicts of interest to disclose.
Reprints: Rumeal D. Whaley, MD, Department of Laboratory Medi- cine and Pathology, Mayo Clinic, Rochester 55905, MN (e- mail: whaley.rumeal@mayo.edu).
All figures can be viewed online in color at www.anatomicpathology. com.
Copyright @ 2026 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/PAP.0000000000000526
in formal consultations of challenging cases. The major perceived challenge was lack of exposure to sufficient num- bers of cases to become experienced in handling adrenal cortical specimens.8 Herein, we review literature regarding adrenal cortical neoplasms and strive to provide insights into the practical evaluation of these lesions.
ADRENAL CORTICAL CARCINOMA
Presentation
In the United States, the incidence of adrenal cortical carcinoma (ACC) is 0.5 to 2 cases per million per year. ACC impacts both adults (peak 50 to 69 y of age) and children (peak <5 y of age). Patients may present with signs and symptoms of mass effect and/or hormonal excess.9 ACC presents with invasion of the surrounding tissues and metastatic disease at the time of diagnosis in 18% to 26% and 21% to 46%, respectively. The prognosis overall is poor with median overall survival of 17 months.10 The vast majority of ACCs are greater than 4 cm.4,5,11-13 Tumor size and weight in and of themselves are important in the evaluation of adrenal cortical neoplasms. Tumors weighing 50 g or more are worrisome for malignancy, and those weighing 100 g are very worrisome for malignancy. Depending on criteria used 0.1% to 14% of ACCs are incidentalomas.9,10 ACC measuring less than 4 cm are quite rare.1,9,13,14 In a study of adrenal incidentalomas by the Cleveland Clinic 2 of 264 resected incidentalomas (out of a total of 1815, including those managed nonoperatively) that were <4 cm were ACC.13 An international study (21 centers, 14 countries) included 98 ACCs, 43 were incidentally discovered, and 2 were <4 cm.15 Signs of cortisol hormone excess include hypertension, dyslipidemia, diabetes, muscle weakness, and central obesity. Androgen excess in females can result in virilization such as increased muscle mass, facial hair, deepening of voice, and amenorrhea. Estrogen excess in males can lead to feminization with gynecomastia and impotence. Excess aldosterone can lead to hypertension. Cortisol (30% to 40%) and sex hormones (26% to 40%) constitute most of functional ACCs, while aldosterone production is rare (2%) in ACC.16 Approximately 40% of ACC are nonfunctional.16
Macroscopic Findings
The macroscopic appearance is often tan to yellow with frequent hemorrhage and necrosis. When evaluating myxoid adrenal cortical neoplasms, the myxoid material may be macroscopically evident. As histologic features may not be uniform throughout a tumor, generous sampling may be required to identify capsular invasion, mitotic activity, and vascular invasion.4,5,17 Although most ACC are large (median 10 to 11 cm) specific size and/or weight criteria only apply to oncocytic and pediatric ACC.4,5,12,17,18
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Microscopic Findings
Histologically, ACCs resemble adrenal cortical tissues usually with the presence of a thick fibrous capsule (Fig. 1A). The growth patterns can be varied from tumor
to tumor and within a tumor. ACCs demonstrate a variety of architecture patterns (Figs. 1B, C), including diffuse, alveolar, cords, and nests often with no intervening stroma. Most conventional ACCs are composed of predominantly
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lipid-poor cells with eosinophilic cytoplasm. The nuclei are typically round and regular with variably prominent nucleoli. Endocrine-type atypia may be present, which is nonspecific. Necrosis ranges from focal to diffuse and must be separated from degenerative changes and infarction,
which is a particular problem when evaluating oncocytic adrenal cortical neoplasms who are prone to ischemic-type necrosis.4 ACCs can occasionally be cystic necessitating extensive evaluation of cystic adrenal lesions.19 In challeng- ing cases, mitotic activity is inconspicuous requiring
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evaluation of numerous sections for “hot spot” areas of mitotic activity (Fig. 2). Identifying mitotic figures may be an arduous process in neoplasms with low proliferation
indices, and artifacts, irregular nuclei, and karyorrhexis must be distinguished from mitotic figures.4,20 The identi- fication of invasive growth may require extensive sampling
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| System/criteria | Indication |
|---|---|
| Weiss system* Modified Weiss system* Helsinki score Reticulin algorithm (adult) | Adults with conventional adrenal cortical neoplasms Adults oncocytic adrenal cortical neoplasms Pediatric adrenal cortical neoplasms |
| Lin-Weiss-Bisceglia criteria | |
| Wieneke Modified Wieneke | |
| Reticulin Algorithm (Pediatric) | |
| *The Weiss systems may not reliably classify myxoid adrenal cortical neoplasms. |
of the tumor. The capsule of adrenal cortical carcinomas can be irregular and distorted presenting its own challenges in interpretation. Metaplasia (lipomatous and myelolipom- atous) and renal adrenal fusion may complicate the assessment of invasion (Fig. 3). Nests of adrenal cortical cells are often found impinging on vascular spaces making the assessment of vascular invasion challenging. Vascular invasion may be recognized clinically or macroscopically with extension into large veins and vena cava. However, these are not the cases that are diagnostically challenging. Many adrenal cortical carcinomas can be diagnosed in the absence of both capsular and vascular invasion (Fig. 4). Angioinvasion may the best predictor of metastatic disease and worse outcomes.21 Identification of tumor forming a thrombus associated with fibrin has been suggested to correlate better with metastatic disease. Tumors can be friable and thus free-floating carcinoma within a lumen should be interpreted with caution. Histologic subtypes of ACC include conventional, oncocytic, myxoid, and sarcomatoid.17,18 Conventional ACC is by far the most common followed by oncocytic, myxoid, and sarcomatoid ACCs.
Oncocytic Adrenal Cortical Carcinoma
Oncocytic ACC is composed of neoplastic cells with greater than 90% oncocytic cytoplasm.4 This 90% criteria requires the tumor be extensively sampled, as the Lin- Weiss-Bisceglia system for evaluating adrenal cortical neoplasms requires that the tumor be at least 90% oncocytic.4,22 Oncocytic adrenal cortical carcinomas may have high nuclear grade and occasionally show marked nuclear pleomorphism. Oncocytic ACCs often have diffuse architecture, thus diffuse architecture and nuclear grade are not criteria when evaluating oncocytic adrenal cortical neoplasms in the Lin-Weiss-Bisceglia system. Using the Weiss system to prognosticate an oncocytic adrenal cortical neoplasm may overestimate its malignant potential.4 Thus,
TABLE 2. Weiss Criteria
High nuclear grade (Fuhrman grade III or IV)
> 5 mitotic figures/10mm2 (~50 HPF)
Abnormal mitotic figures < 25% of tumor cells with clear cytoplasm
Diffuse architecture (> 1/3 of tumor) Tumor necrosis Venous invasion (smooth muscle-walled vessels)
Sinusoidal invasion (no smooth muscle in vessel wall)
Capsular invasion
Presence of ≥3 correlates with malignant behavior.
the Lin-Weiss-Bisceglia system is the standard for oncocytic adrenal cortical neoplasms, and more recent systems such as the Helsinki criteria and the reticulin algorithm may be utilized.4-6,12,14,23 Bisceglia et al found approximately 30% of oncocytic ACCs to be functional and oncocytic ACCs had a median survival of 58 months, which was significantly better than the 14 to 32 months for conventional ACCs.22 A more recent study from MD Anderson Cancer Center compared 30 borderline/malignant oncocytic adrenal cort- ical neoplasms with 241 conventional ACCs found similar clinical pathologic behavior, recurrence-free, and overall survival were similar.24
Myxoid Adrenal Cortical Carcinoma
Myxoid ACCs can have trabecular, pseudoglandular, and cystic growth in an acellular myxoid background (Fig. 5). The cytoplasm ranges from clear, eosinophilic, to amphophilic. The nuclei are small with minimal nuclear pleomorphism. Nucleoli are typically small. Myxoid features in adrenal cortical neoplasms range from a focal finding up to the entirety of the tumor.11 Myxoid features have been described in adrenal cortical adenomas using the Weiss system. Even so, the Weiss system may not be appropriate for lesions with significant myxoid compo- nents. Papotti et al11 recognized the problems of classifying myxoid adrenal cortical neoplasms. Unlike conventional adrenal cortical carcinomas with focal (5% to 20%) myxoid change, in which 1 of the 4 died of disease and3 were alive with disease, the 10 cases classified as myxoid adrenal cortical carcinomas had prominent myxoid change, small cells, mild atypia, cords, and microcysts. Of these 10 myxoid ACCs, 6 patients died of disease, 1 was alive with disease, and 3 were live with no disease. One of 2 cases with a Weiss score of 1 had a fatal outcome.11 Evaluating myxoid adrenal cortical neoplasms with a different scoring system (Helsinki criteria or reticulin algorithm) with a Weiss scores less than 3 may be appropriate.5,12 Given its unusual appearance, consideration should be given to the possibility of a metastasis from breast, stomach, among other sites or even a sarcoma when evaluating a tumor in the adrenal gland with myxoid change. A functioning myxoid ACC may be helpful in distinguishing myxoid adrenal cortical neoplasms from metastasis. Even though myxoid features are unusual, the immunophenotype of these tumors is similar to conventional adrenal cortical neoplasms.11,25
Sarcomatoid Adrenal Cortical Carcinoma
ACCs with sarcomatoid growth are exceedingly rare. These neoplasms can demonstrate a malignant unclassified spindle cell proliferation and/or heterologous
| TABLE 3. Modified Weiss System | |
|---|---|
| Score of 0 (absent) or 1 (present) | Calculation |
| High mitotic rate [> 5 mitotic figures/10mm2 (~50 HPF)] < 25% of tumor cells with clear cytoplasm Abnormal mitotic figures Tumor necrosis | 2*(presence of high mitotic rate) + 2*(<25% clear cells) + (presence of abnormal mitoses) + (presence of necrosis) + (presence of capsular invasion) |
| Capsular invasion | |
| Score of ≥ 3 correlates with malignant behavior. | |
differentiation. Sarcomatoid ACCs appear to behave more aggressively than conventional ACCs.26 The presence of a conventional ACC component enables a definitive diag- nosis. If the tumor is nonfunctional or no adjacent conventional ACC is identified, then the diagnosis of sarcomatoid ACC is particularly challenging. Secondary involvement of the adrenal gland by various sarcomatoid carcinomas or sarcomas (Fig. 6A) is more common than sarcomatoid ACC. The immunophenotype (particularly expression of SF1) in a panel of immunohistochemical studies may allow for separation from secondary involve- ment. Sarcomatoid carcinomas and dedifferentiated/undif- ferentiated melanoma can be challenging to distinguish and may show under expression of lineage-specific markers. In addition, the molecular findings of sarcomatoid ACC are nonspecific.26 Another rare tumor to consider composite pheochromocytoma with malignant peripheral nerve sheath tumor, among others (Fig. 6B).
Risk Stratification
Multiparameter systems for stratifying/prognosticat- ing adrenal cortical neoplasms are listed in Table 1. No system is completely sensitive and specific in all settings and may give discordant results in an individual lesion. The parameters, while conceptually straightforward often are marred by the complexity of interpretation of any given section by a given pathologist. Many ACCs are malignant at first glance (large size/weight, high nuclear grade, tumor necrosis, conspicuous mitotic activity), and it is the low- grade tumors which require multiparameter algorithms that are the most challenging. In an adrenal cortical tumor with borderline features, it is often helpful to submit additional sections. In addition, molecular evaluation and/or surro- gate markers of genomic alterations may be of used (see immunohistochemistry and genomic sections).
Weiss Criteria
On the basis of 43 adrenal cortical tumors, Dr. Weiss provided 9 parameters to stratify adrenal cortical
neoplasms (Table 2).1,2 The criteria are nuclear grade, mitotic rate, atypical mitotic figures, nonclear cytoplasm, diffuse architecture, necrosis, invasion of venous structures, invasion of sinusoidal structures, and invasion of the capsule of the tumor. The mitotic rate was defined as counting mitotic figures on 10 high-power fields containing the greatest number of mitotic figures on 5 different slides. If less than 5 slides were available for a case, a greater number of fields per slide were used to make a total of 50 high-power fields. Atypical mitotic figures were defined as having an abnormal distribution of chromosomes or excessive number of mitotic spindles. The cytoplasm was evaluated for the percentage of clear/vacuolated cells resembling the normal zone of fasciculata. Diffuse archi- tecture was defined as greater than 1/3 of the tumor formed patternless sheets of cells and was regarded as nondiffuse when 2/3 of the tumor showed organized into parts, whether nesting trabecular or of another type. Necrosis was regarded as present when occurring in at least confluent nests of cells. A sinusoid was arbitrarily defined as an endothelial-lined vessel in the adrenal gland with little supporting tissues and a vein was defined as an endothelial- lined vessel with smooth muscle has a component of its wall. Invasion of the capsule was present when nests are cords of the tumor extended through the capsule with a corresponding stromal reaction. No single criterion was definitive. None of the 24 tumors with a score of 2 or less recurred or metastasized. While 18 of 19 tumors with 4 or more criteria either recurred or metastasized in the original 1984 manuscript.1 In a subsequent paper, Weiss et al2 proposed stratification of low and high grade based upon the threshold of 20 mitotic figures per 50 high-power field, which is still in use today. As one patient with a Weiss score of 3 died of disease, the threshold for malignancy was lowered from Weiss score of 4 to 3, as it remains today.2 Currently, the Weiss system remains the most widely used for diagnostic purposes, the most validated, and is prognostic. A higher Weiss score correlates with worse outcomes.12 Thus, providing a numerical score in addition
| TABLE 4. Lin-Weiss-Bisceglia Criteria | ||
|---|---|---|
| Major criteria | Minor criteria | |
| High mitotic rate: > 5 mitoses per 50 HPF Atypical mitotic figures | Tumor size >10 cm | |
| Tumor weight >200 g | ||
| Venous invasion | Tumor necrosis | |
| Capsular invasion | ||
| Sinusoidal invasion | ||
| Presence of any major criteria correlates with malignant Presence of only minor criteria is considered borderline No criteria correlates with benign behavior. | behavior. malignant potential. | |
| TABLE 5. Helsinki Scoring System | |
|---|---|
| Score of 0 (absent) or 1 (present) | Calculation |
| High mitotic rate [> 5 mitotic figures/10 mm2 (~50 HPF)] Tumor necrosis Ki-67 proliferation index: Decimal fraction of nuclei positively labeled | 3*(presence of high mitotic rate) + 5*presence of necrosis + Ki-67 proliferation index |
| Score > 8.5 correlates with metastatic potential. | |
to the diagnosis of carcinoma may aid in the stratification of patients. The main weaknesses to the Weiss criteria are subsets of adrenal tumors such as oncocytic, myxoid, and pediatric, for which other systems are available.5,6,11,12 Also, Dr. Weiss acknowledged tumors that may fall within the border zone of this classification system.1 In our practice, these cases (Weiss score 2) are shared among the group, and additional sectioning and/or analysis by addi- tional algorithms may be utilized.
Modified Weiss
Comparing 24 malignant with 25 benign adrenal cortical neoplasms, Aubert and colleagues reassessed the Weiss system.7 While presented as calculation (Table 3), in practice the number of parameters are reduced while both mitotic activity and decreased clear cell component count as 2 points rather than 1. This system is much less commonly used than the standard Weiss system of 1989.
Lin-Weiss-Bisceglia
Lin-Weiss-Bisceglia system is restricted to adrenal cortical neoplasms that are exclusively or predominantly composed of cells with oncocytic cytoplasm (90% onco- cytes). These oncocytic adrenal cortical neoplasms often have a high nuclear grade and diffuse architecture that can be overdiagnosed as malignant by the Weiss system.4 Thus, the Lin-Weiss-Bisceglia system (Table 4) was adapted from the Weiss system. The features were separated into major and minor criteria. The presence of any major criterion is sufficient for the diagnosis of oncocytic ACC. The absence of all major and minor criteria support the diagnosis of oncocytic adrenal cortical adenoma. The presence of any minor criteria classifies the neoplasm as an oncocytic adrenal cortical neoplasm of borderline malignant poten- tial. The major criteria are mitotic rate of more than 5 mitotic figures per 50 high-power fields (10 mm2), atypical mitotic figures, or venous invasion. The minor criteria are large size (>10 cm and/or >200 g), necrosis, capsular invasion, or sinusoidal invasion. A challenge to all classification systems, including the Lin-Weiss-Bisceglia criteria, is a problem of receiving neoplasms that are fragmented. Thus, pathologists should correlate with radiology and note this in the report.
Helsinki Scoring System
The Helsinki predictive score further decreases the number of parameters evaluated (Table 5). The Helsinki score incorporates Ki-67 proliferation index along with the mitotic rate and necrosis to result in a score.6 Ki-67 proliferation indices were assessed using a computer- assisted image analysis. The calculation is 3 x mitotic rate greater than 5/50 high-power fields + 5 x presence of necrosis + proliferation index. Tumors are stratified based on a 8.5 Helsinki score threshold. A score of <8.5 correlated with adenomas, and a score >8.5 was seen in tumors with metastatic disease. This study included 177 adrenal cortical neoplasms. Thirty of these tumors were malignant by the Weiss system (score ≥3). Fifteen had a Helsinki score less than 8.5 (4 had a Weiss score of > 3, 2 had necrosis, and 10 tumors were under 4 cm), and none of the patients died of disease. Fifteen had score a Helsinki score > 8.5 (12 had a Weiss score ≥7, 14 had necrosis, and no tumor was under 4 cm). Therefore, a score greater than 8.5 is highly suggestive of metastatic potential and suggests a diagnosis of malignancy in this prognostic system. Duregon et al12 with a greater number of ACC (n =225; Weiss score ≥ 3) suggested Helsinki score thresholds of <13 and > 19 better stratified patients. A Helsinki score of 28.5 and a Ki-67 of 20.5% were suggested as predictors disease-related death. In addition, the Helsinki score was shown to be useful in oncocytic and possibly myxoid subtypes. 12
Reticulin Algorithm
On the basis of the evaluation of 92 ACCs, Volante et al14 proposed a simplified diagnostic algorithm for the prognostication adrenal cortical neoplasms that incorpo- rated reticulin histochemical staining (Table 6). One of the more subjective criteria in the Weiss system is diffuse growth. The use of reticulin allows for the identification of patterns of growth that correlate with ACC. Areas of diffuse growth show loss of reticulin. In addition, areas with cord-like or nested growth can show loss of reticulin highlighting the importance of architecture as a distinction of adenoma and carcinoma.14 A disrupted reticulin net- work was defined by the loss of continuity of reticular fibers in a high-power field (usually found in more than half of the tumor). An imaginary line can connect opposite sides of the
TABLE 6. Reticulin Algorithm
Quantitative changes are defined by loss of continuity of reticulin fibers (recognized by one being able to draw path connecting 2 opposite sides of HPF without being cutoff by reticulin fiber) in at least 1/3 of tumor. Qualitative changes are defined as variable and irregular thickness with a frayed appearance surrounding a single cell or, more rarely, small groups of cells.
High mitotic rate [> 5 mitotic figures/10 mm2 (~50 HPF)]
Tumor necrosis
Venous invasion
Presence of altered reticulin framework with at least one additional feature correlates with malignant behavior.
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field of view unobstructed by reticulin fibers. This was a consistent finding in ACC. Thus, the presence of an intact reticulin framework supported the diagnosis of adrenal
cortical adenoma. A disrupted reticulin network and high mitotic activity [greater than 5 mitotic figures per 50 high- power fields (5/10 mm2)], necrosis, or venous invasion is
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TABLE 7. Wieneke/AFIP Classification
Tumor size > 10.5 cm Tumor weight > 400 g
Extension into periadrenal soft tissue or beyond Invasion of inferior vena cava
Venous invasion Capsular invasion
Tumor necrosis > 15 mitotic figures 20 HPF
Abnormal mitotic figure
Presence of ≥ 4 criteria correlates with malignant behavior. Presence of 3 criteria is considered uncertain malignant potential. Presence of <3 criteria correlates with benign behavior.
sufficient for the diagnosis of ACC.14 Thus, the evaluation adrenal cortical neoplasia was simplified from 9 parameters to the evaluation of the reticulin framework and 3 parameters and needing only one for the diagnosis of malignancy. The original description of disrupted reticulin network was later modified to include the concept of qualitative disruptive changes. These were described as reticulin networks made of fibers having variable and irregular thickness with a frayed appearance surrounding a single cells or more rarely small groups of cells.5 The description of altered reticulin is more challenging to understand than seeing the normal reticulin network compared with quantitative and qualitative alterations (Fig. 7). The original study correlates well with ACCs categorized as malignant by the Weiss system and with less parameters to evaluate might improve reproducibility. The reticulin algorithm has been suggested to be useful in ACC subtypes (oncocytic, myxoid) and a modified reticulin algorithm has been proposed in pediatric cases.5,23,27 Selection of the slide to evaluate is key, as areas of degeneration or hemorrhage will have altered reticulin networks.28
Immunohistochemistry
Other than Ki-67, immunohistochemistry may not always be needed to evaluate an adrenal cortical neoplasm. Surrogate markers of genomic alterations (eg, p53, IGF2, ß-catenin) can be of use in challenging cases. Positive results (aberrant expression) may be of use in equivocal cases. Genomic evaluation may be warranted to confirm the suspected genetic aberration. Insulin-like growth factor 2 (IGF2) expression has been reported in greater than 90% of adult ACCs and is sensitive marker for adult and pediatric adrenal cortical carcinoma.21,29,30 Aberrant p53 expression may identify a subset of adult ACC; however, these tend to be high-grade malignancies and not a diagnostic dilemma.17
TABLE 8. Modified Wieneke Criteria*
Capsular invasion Venous invasion
Tumor necrosis
> 15 mitotic figures 20 HPF
Ki-67 >15%
Presence of ≤2 criteria: favorable histology
Presence of ≥2 criteria: unfavorable histology
*Only applies tumors weighing > 200 g with a R0 initial resection or tumors with retroperitoneal lymph node involvement, R1/2 initial resection, or tumor spillage. Tumors with R0 resection < 200 g or distant metastatic disease are excluded.
Aberrant ß-catenin expression may be seen in ACC but can be seen in adenomas.31 Phospho-histone H3 highlights mitotic figures and may have particular use in evaluating adrenal cortical neoplasms with low proliferative indices or ones that are nearing the threshold on routine examination.20
Ki-67
Assessment of ACC proliferation is fundamental to the evaluation of adrenal cortical carcinoma.32 This includes both counting mitotic figures and the Ki-67 proliferation index. If Ki-67 is not performed as part of a multiparameter scoring system, it should be performed, as it has clinical significance in all age groups.7,12,20,29,33 A European study of more than 500 adrenal cortical carcinomas suggested clinical outcomes (median survival 180.5, 113.5, and 42 mo) can be stratified based on Ki-67 proliferation index using <10%, 10% to 19%, and greater than 20% as thresholds.33 They concluded that Ki-67 proliferation indices were the most important factor inpredicting recurrences following R0 resection.33 A thresh- old of 15% has been suggested as a threshold of malignancy in pediatric adrenal cortical tumors.29,34,35 A threshold of 20% has been suggested for oncocytic ACCs as predicting progressive disease.36 Manual counting or computer- assisted image analysis is recommended and “eyeballing” Ki-67 proliferation index is discouraged.37
Differential Diagnosis
Knowing the status of the contralateral adrenal gland may aid in the review, as bilateral adrenal masses maybe be a consequence of adenomas, hyperplasia (pituitary or ACTH driven or congenital adrenal hyperplasia), atrophy, or metastatic disease. Clinical presentation and serum levels may aid, as the co-occurrence of unrelated entities is possible.9 Adrenal gland biopsies are often performed in patients with a known malignancy elsewhere who have undergone radiographic imaging which identified a mass in the adrenal gland suspicious for metastatic disease. If a tumor is nonfunctional or there is a diagnostic quandary regarding the case, then a panel of immunohistochemical studies is usually performed-often including steroidogenic factor 1 (SF1). The remaining markers are less sensitive and less specific. Even so, SF1 can be seen in any steroidogenic tumor (similar to inhibin-«) and it may not be available in every diagnostic laboratory. Keratins, particularly AE1/ AE3 and CAM 5.2, usually show at least some staining, but can be negative, particularly in high-grade cases. Inhibin-a and Melan A are useful in a panel but are not relied on in isolation.17,18,38 Inhibin-a is often only positive and functioning adrenal cortical tumors.17,18,38 Other scenarios we see occasionally in our consultation service are upper pole renal masses submitted as renal biopsies that are actually adrenal cortical adenomas and metastatic SMARCA4-deficient neoplasms. Lipid-rich adrenal cortical tissue shows morphologic overlap with clear cell renal cell carcinoma. This can be easily resolved as long as the possibility of adrenal cortical tissue being sampled in an upper pole lesion is considered. SMARCA4-deficient neo- plasms often have limited expression of commonly used biomarkers, which leads to a challenging diagnosis (Fig. 8). Rare cases express inhibin-« (personal observations). In addition, biopsies directed toward a right adrenal gland mass occasionally are composed of inadvertently sampled liver parenchyma rather than neoplasm in the adrenal
TABLE 9. Pediatric Reticulin Algorithm
Quantitative changes are defined by loss of continuity of reticulin fibers (recognized by one being able to draw path connecting 2 opposite sides of HPF without being cutoff by reticulin fiber) in at least 1/3 of tumor. Qualitative changes are defined as variable and irregular thickness with a frayed appearance surrounding a single cells or more rarely small groups of cells. High mitotic rate (> 15 mitotic figures/20 HPF)
Tumor necrosis
Venous invasion
Presence of altered reticulin framework with an additional feature correlates with malignant behavior.
gland. Strong diffuse expression of keratin is not typical of ACC and raises the possibility of metastatic carcinoma. However, ACC may show strong keratin immunoreactivity. The most common sarcoma to involve an endocrine organ, including the adrenal gland, is epithelioid angiosarcoma, which is invariably positive for keratin.39 Thus, a panel of immunohistochemical studies is recommended in the evaluation of unusual tumors in endocrine organs. Kera- tins, PAX8 (monoclonal), and SF1 can reliably distinguish most cases of metastatic renal cell carcinoma from ACC.17,18,38 TFE3-rearranged renal cell carcinoma and TFEB-altered renal cell carcinomas can under express keratins and express Melan A.40 A cautious approach should be taken to the evaluation of a sarcomatoid malignancy involving the adrenal gland, as sarcomatoid renal cell carcinoma under express lineage markers and have heterologous differentiation.41 Pheochromocytomas are often diagnosed clinically. On occasion the histologic pattern of adrenal medullary tumors can overlap signifi- cantly with adrenal cortical tumors. As synaptophysin is positive in both, GATA3, chromogranin-A, and SF1 should resolve most cases. Metastatic melanoma and adrenal cortical tissue express Melan A, a panel of immunohistochemical studies should resolve most cases. 17,18,38
Pediatric Adrenal Cortical Carcinoma
ACC accounts for 5.6% of pediatric malignancies.42 There is a female predominance and most present at age 0 to 4 with a 2nd peak in adolescence.42 The prognosis is better than the adult population.42 In contrast to their adult counterparts, the morphology and proliferation indices portending a poor prognosis in adult adrenal tumors may not be applicable for pediatric adrenal cortical tumors.3 Adult classification systems may overestimate the
| T category | T criteria |
|---|---|
| T0 | No evidence of primary tumor |
| T1 | Tumor less than or equal to 5 cm in greatest dimension, no extra-adrenal invasion |
| T2 | Tumor greater than 5 cm, no extra-adrenal invasion |
| T3 | Tumor of any size with local invasion, but not invading adjacent organs |
| T4 | Tumor of any size with invasion of adjacent organs (kidney, diaphragm, pancreas, spleen, or liver) or large blood vessels (renal vein or vena cava) |
| N category | N criteria |
| N0 | No regional lymph node metastasis |
| N1 | Metastasis in regional lymph node(s) |
| M category | M criteria |
| M1 | Distant metastasis |
| Appropriate for all age groups. | |
malignant potential in pediatric tumors. Similar to adults tumors no single histologic finding is diagnostic of outcome in pediatric tumors. The Wieneke criteria (Table 7), also referred to as United States Armed Forces Institute of Pathology (AFIP) criteria for pediatric adrenal cortical neoplasms, was based on a series of 83 pediatric adrenal cortical neoplasms and has been validated in multiple studies.3,27,35 The criteria are tumor weight greater than 400 g, tumor size greater than 10.5 cm, extension into the periadrenal soft tissue and/or adjacent organs, invasion of the vena cava, venous invasion, capsular invasion, presence of tumor necrosis, greater than 15 mitotic figures per 20 high-power fields, and presence of atypical mitotic figures.3 Of the 83 cases in the Wieneke study, 37 had a score of ≤2 and no patient died of disease in this group. Of the 18 cases in the indeterminate category, 3 had clinically malignant behavior. Of the 28 cases with ≥4 more criteria, 18 behaved in a malignant manner.3 In addition, histologically malig- nant (score >3) resulted in clinically favorable outcomes.3,35 As with the original Weiss criteria, some found the Wieneke criteria to be observer dependent.35 To address this, a “modified Wieneke” criteria (Table 8) was proposed based on 95 pediatric adrenal cortical tumors (24 malignant by original Wieneke criteria), which reduced the parameters evaluated from 9 to 5.35 This system was proposed for use in a select group of tumors (Children’s Oncology group Stage II and Stage III) in an effort to guide adjuvant treatment (as the guidelines are more clear for stage I and stage IV disease). No death or events occurred when a tumor had no necrosis. Importantly, no tumor with a Ki-67 proliferation index <15% was associated with aggressive disease. However, others have reported pediatric ACC with <15% Ki-67 proliferation index that did have aggressive disease.29,34 Thus, no single criterion can predict outcome and multiparameter risk stratification may prove most useful. A reticulin algorithm for pediatric adrenal cortical neoplasms (19 of 59 cases diagnosed malignant by original Wieneke criteria) has been suggested for pediatric adrenal cortical neoplasms.27 Of the patients with unfav- orable outcomes 90% had quantitative reticulin alterations. The proposed pediatric reticulin algorithm (Table 9) incorporates the higher mitotic threshold used in the original Wieneke criteria (>15 mitotic figures per 20 high-power fields).27 In addition, a Helsinki predictive score cutoff score of 24 has been suggested for pediatric adrenal cortical tumors.43 The “modified Wieneke” criteria, Helsinki predictive score, and pediatric reticulin algorithm appear promising, but await further validation. Nonsyn- dromic cases are uncommon in the pediatric population. Thus, genetic evaluation is recommended.
Grade and Staging
Currently, ACC is graded based upon mitotic activity. Low grade is defined as ≤ 20 mitoses/10 mm2 and high
grade is defined as >20 mitoses/10 mm2.2,17 Grading tumors is often time-consuming and challenging. Digital imaging and artificial intelligence-based mitotic figure identification may alleviate this issue. The current AJCC staging is based upon a 5 cm threshold and extent of invasion (Table 10).44
Genomics
Most ACCs are sporadic in the adult population, while genetic predisposition syndromes account for most pediatric cases. Driver genetic alterations in sporadic cases include Wnt-signaling pathway (CTTNB1 mutations and ZNRF3 deletions), cell cycle regulation (TP53, RB1, MDM2, CDK4, CDKN2A mutations), chromosome main- tenance/chromatin remodeling (DAXX, ATRX, MEN1, TERT mutations, and TERF2 amplifications), PKA path- way (PRKARIA mutation), and aberrant IGF2 signaling.45,46 Li-Fraumeni syndrome accounts for the majority (50% to 80%) of carcinomas with the germline associations.17 Other syndromes include Lynch syndrome, multiple endocrine neoplasia 1, Beckwith-Wiedemann syn- drome, familial adenomatous polyposis, Carney complex, neurofibromatosis type 1, and congenital adrenal hyper- plasia, but ACC is uncommon in most of these settings.17 ACC is so rare that germline testing is recommended. Through a combination of genomic, transcriptomic, and epigenomic data, ACC can be clustered into 3 subtypes (referred to as cluster of clusters [CoC]).46 CoC I included cases that were clinically indolent. These tumors were CpG island methylator phenotype (CIMP) low, had multiple whole chromosome arm gains and losses, and often did not have an identifiable driver genomic alteration. COC II were deemed intermediate risk. These were CIMP intermediate, chromosomal copy number profile was variable with frequent alterations in p53 and Wnt pathways, and histone modifications genes. CoC III were clinically aggressive disease. These tumors were CIMP high, frequent chromoso- mal breaks with often loss of 1P, had frequent alterations in p53 and Wnt pathways, and histone modifications gene. IGF2 overexpression is seen it the majority of ACC regardless of subtype.46 While this level of investigation is not routine in the day-to-day sign-out, this does provide insight and rationale for immunohistochemical studies such as p53, beta-catenin, and IGF2 with targeted genomic investigation in challenging cases that may lead to more individualized care. Liquid biopsies may prove useful in the evaluation of patients with the adrenal cortical nodules. Liquid biopsies are a mini-invasive sample collection method that focuses on blood or body secretions for the detection of molecular alterations, tumor cells, and metabolites and is in use for a variety of cancers. This technique has the potential to diagnose and monitor for progression.47
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