Histopathological study of adrenocortical carcinoma with special reference to the Weiss system and TNM staging and the role of immunohistochemistry to differentiate it from renal cell carcinoma
ABSTRACT
Background: Adrenocortical carcinomas (ACC) are rare tumors with an incidence of 1-2/million/year. They account for 0.05-0.2% of all malignancies. Aims and Objectives: This study was aimed to evaluate the Weiss system to diagnose ACCs and to compare it with TNM staging. The role of immunohistochemistry (IHC) was also evaluated to differentiate ACC from other differential diagnoses especially, renal cell carcinoma (RCC). Materials and Methods: A total of 10 ACCs were included from April, 2000 to March, 2012. All the relevant information like weight, tumor size, gross features was recorded. Multiple sections were taken for histologic examination. Immunomarkers like vimentin, synaptophysin, Melan-A, calretinin, inhibin, EMA, cytokeratin, and Ki-67 were used. Results: Out of 10 cases of ACCs (diagnosed by the Weiss system), the tumors were in TNM stage I (1 case), stage II (2 cases), stage III (5 cases), and stage IV (2 cases). The Weiss score in stages I-IV was 4; 5-7; 6-8; and 5-9 respectively. ACCs were positive for vimentin, inhibin, Melan-A, calretinin and negative for EMA and cytokeratin. Proliferative index (Ki-67/MIB-1) was ≥ 20 % (20-65%). Conclusion: Both the Weiss system and TNM staging are useful in predicting the malignant behavior and prognosis of ACC. Weight and tumor size, though originally not included in the Weiss system, are also important parameters. In lower stages (stages I and II), the Weiss score is low (4-7) while the score is high (6-9) when the tumor is in higher stages (stages III and IV). IHC plays a vital role to confirm the diagnosis and to exclude the possibility of RCC.
KEY WORDS: Adrenocortical carcinoma, immunohistochemistry, TNM staging, Weiss system
INTRODUCTION
Adrenocortical carcinoma (ACC) is a rare malignant tumor with an incidence of 1 — 2 cases per million per year.[1]
The Weiss scoring system has been widely used for the histologic diagnosis of ACC. The nine histological parameters evaluated in this system are high nuclear grades (nuclear grades III and IV based on the criteria of Fuhrman et al.), mitotic rate >5/50 high power fields (HPF), atypical mitotic figures, clear tumor cell cytoplasm (less than 25% tumor cells), diffuse architecture (greater than 33% of tumor), necrosis, venous invasion, sinusoidal invasion, and capsular invasion.[2] A tumor is labeled malignant when it meets four or more of these histological criteria.
The tumor, lymph node, and metastasis (TNM) classification system proposed by the International
Union Against Cancer (UICC) and the American Joint Committee on Cancer is the most frequently used classification to assess the local extension of the primary tumor, lymph node involvement, and the presence of distant metastasis. The TNM classification is one of the most important prognostic tools in these cases.
This study was done to evaluate the role of the Weiss system in the diagnosis of adrenocortical carcinoma and to compare it with the TNM staging system. Till date, to the best of our knowledge, there is no such correlation study between the Weiss system and the TNM staging system and our study is probably one of the first of its kind.
MATERIALS AND METHODS
This study was carried out over a period of 12 years from April 2000 to March 2012 in the Pathology department of Medical College, Kolkata. We studied
Santosh Kumar Mondal, Senjuti Dasgupta, Parul Jain, Palash Kumar Mandal, Swapan Kumar Sinha
Department of Pathology, Medical College, Kolkata, West Bengal, India
For Correspondence: Dr. Santosh Kumar Mondal, “Teenkanya Complex”, Flat 1B, Block B, 204 R N Guha Road, Dumdum, Kolkata - 700 028, West Bengal, India. E-mail: dr_santoshkumar@ hotmail.com
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DOI: 10.4103/0973-1482.119329
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Mondal, et al .: Adrenocortical carcinoma, Weiss score, immunohistochemistry
the detailed gross and histological features of 11 cases, which were provisionally diagnosed as ACCs by clinical, radiological, and biochemical features [Figure 1].
A panel of antibodies including vimentin, synaptophysin, Melan-A, calretinin, inhibin, EMA, cytokeratin, and Ki-67 was used. In one case, the gross, microscopic, and immunohistochemical evaluation proved it to be RCC. This case was excluded from our study. IHC was done in the other 10 cases to confirm the diagnosis of ACC and to exclude other tumors, particularly RCC, so finally a total of 10 cases were confirmed to be ACC.
The nine histological parameters in accordance with the Weiss criteria of each of these 10 tumors were noted [Figures 2 and Figure 3]. Weiss scoring was done. Local invasion, invasion of adjacent organs, regional lymph node involvement and distant metastases to lungs, retroperitoneal lymph nodes, liver, and other organs were recorded from the operative notes and enquiry from the surgeons. TNM staging of the tumors was done.
RESULTS
In one case, grossly the tumor was variegated on cut section (characteristic of RCC) and on microscopic examination, it turned out to be a case of clear cell RCC (> 90 % clear cells were seen). The tumor cells, in this case, were immunoreactive for EMA and cytokeratin and they were negative for vimentin, synaptophysin, and calretinin. Periodic acid — Schiff (PAS) stain was done and PAS-positive material (glycogen) was demonstrated within the cytoplasm of the tumor cells. We excluded this case from our study as it turned out to be RCC.
Of the 10 cases diagnosed to be ACC, 6 were females and 4 were males with an age range of 6 — 78 years, average age being 49.7 years. Two patients were in the pediatric age group (6 years and 11 years) and the remaining eight were adults. One case was asymptomatic and rest of the nine cases presented with abdominal pain and a palpable mass. In addition, three cases presented with endocrine symptoms. Among them, two cases presented with virilism and one with Cushing’s syndrome.
The weights of the tumors ranged from 350 to 1800 g with a mean value of 799.3 g. The sizes (greatest diameters) of the tumors ranged from 5 to 21 cm with an average of 10.3 cm. Table 1 shows the clinical features, radiological features, biochemical features, and the gross features of the 10 cases included in our study.
Out of 10 cases of ACC (diagnosed by the Weiss system), 1 case was TNM stage I, 2 cases were stage II, 5 cases were stage III, and 2 cases were stage IV. The Weiss score in stage I was 4; in stage II, 5 — 7; in stage III, 6 — 8, and in stage IV was 6-9.
The tumor architecture was predominantly diffuse (>33% of the tumor) in nine cases. There was one case in stage I which
was in the pediatric age group (6 years) with high nuclear grade, mitotic count > 5/50 HPF and atypical mitotic figures. In stage II, one out of two cases was in the pediatric age group (11 years). None of the cases in stages I and II showed venous
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| Cases | Case No. 1 | Case No. 2 | Case No. 3 | Case No. 4 | Case No. 5 | Case No. 6 | Case No. 7 | Case No. 8 | Case No. 9 | Case No. 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| CL. FEAT. | 6 years M, abd mass | 11 years F, virilism | 57 years F, abd mass, pain | 58 years M, Cush. syn | 46 years F, asympt | 53 years M, abd mass, pain | 50 years F, virilism | 75 years F, abd mass | 63 years F, abd mass, pain | 78 years M, abd mass, pain |
| RADIOL. FEAT | Large mass, het. enh. | Large mass, central necr. | Large mass, floc. calcific. | Large mass, het. enh. | Large mass, central hge. | Large mass, areas of necr | Large mass, het. enh | Large mass, central necr. | Large mass, hge and necr. | Large mass, het. enh. |
| BIOCH. | Serum DHEAS and test. 1 | _ | Ur. cort. î and plasma ACTH Į | _ | Serum | Ur. cort. î and plasma ACTH Į | _ | _ | ||
| FEAT | _ | _ | DHEAS and test. 1 | |||||||
| GROSS | 5 cm, | 6 cm, | 5.5 cm, | 7 cm, | 7.5 cm | 15 cm, | 9 cm, | 8 cm, | 19 cm, | 21 cm, |
| FEAT | 350 g | 442 g | 368 g | 469 g | 543 g | 1744 g | 555 g | 582 g | 1140 g | 1800 g |
| (SIZE, WT.) |
No= Number, CL FEAT= Clinical features, RADIOL FEAT: Radiological features, BIOCH FEAT: Biochemical features, GROSS FEAT: Gross features, WT= Weight, M= Male, F= Female, abd= Abdominal, Cush syn= Cushing’s syndrome, asympt= Asymptomatic, het enh= Heterogeneous enhancement, necr= Necrosis, floc. calcif= Flocculent calcification, hge= Hemorrhage, DHEAS= Dehydroepiandrosterone, test= Testosterone, Ur. cort= Urinary cortisol
| Cases | Case No. 1 | Case No. 2 | Case No. 3 | Case No. 4 | Case No. 5 | Case No. 6 | Case No. 7 | Case No. 8 | Case No. 9 | Case No. 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| WE ISSCRITERIA | ||||||||||
| TNM stage | I | II | II | III | III | III | III | III | IV | IV |
| High nu. grade | + | _ | + | _ | + | + | + | _ | + | + |
| Mit.rate> 5/50hpf | + | + | + | + | + | _ | + | + | + | + |
| Abnormal mitoses | + | + | + | + | _ | + | + | + | _ | + |
| ≤25% clear cells | _ | + | + | + | _ | + | _ | + | + | + |
| >1/3 diffuse arch. | + | + | + | + | + | + | + | + | _ | + |
| Necrosis | _ | + | + | + | + | _ | + | + | + | + |
| Venous invasion | _ | _ | _ | + | + | + | + | + | + | + |
| Sinusoidal invasion | _ | _ | _ | _ | + | + | _ | + | + | + |
| Capsular invasion | _ | _ | + | _ | _ | + | + | + | _ | + |
| Total Weiss score | 4 | 5 | 7 | 6 | 6 | 7 | 7 | 8 | 6 | 9 |
High nu. grade= High nuclear grade, Mit. rate= Mitotic rate, >1/3 diffuse arch - >1/3 diffuse architecture
a
2
b
-
d
c
of 10 cases. Melan-A was positive in six cases. Four cases were positive for calretinin. Ki-67 was found to be ≥20% positive in all 10 cases. Inhibin immunomarker was done in two cases
invasion or sinusoidal invasion. Mitotic count was found to be 6-10 per 50 HPF in stages I and II. In stage III, three out of five cases had necrosis, atypical mitoses, and venous invasion.
Among the seven cases of stages III and IV, six had high mitotic count (≥10/50 HPF) and five had atypical mitotic figures. Of the two patients in stage IV, one had metastasis to the right lung and the other to liver. A correlation between the TNM staging system and the Weiss scoring system has been shown in Table 2.
Immunohistochemical evaluation with a panel of immunomarkers was done in all 10 cases. In two cases, an additional marker, inhibin, was used. On gross examination, these two cases had a variegated appearance as in RCC and on microscopic examination, >25% clear cells were seen. So differential diagnoses of ACC and RCC were given and IHC (including inhibin) was advised for confirmatory diagnosis. Subsequently, both cases turned out to be ACC.
Vimentin and synaptophysin were found to be positive in 8 out
Mondal, et al .: Adrenocortical carcinoma, Weiss score, immunohistochemistry
| Cases | Vimentin | Synaptophysin | Melan-A | Calretinin | Inhibin | EMA | CK | Ki-67% |
|---|---|---|---|---|---|---|---|---|
| No. 1 | +ve | +ve | +ve | -ve | ND | -ve | -ve | 30 |
| No. 2 | +ve | +ve | -ve | +ve | ND | -ve | -ve | 45 |
| No. 3 | +ve | -ve | +ve | -ve | ND | -ve | -ve | 58 |
| No. 4 | +ve | +ve | -ve | +ve | ND | -ve | -ve | 47 |
| No. 5 | +ve | +ve | -ve | +ve | +ve | -ve | -ve | 32 |
| No. 6 | -ve | +ve | +ve | -ve | ND | -ve | -ve | 20 |
| No. 7 | +ve | -ve | +ve | +ve | +ve | -ve | -ve | 55 |
| No. 8 | +ve | +ve | -ve | -ve | ND | -ve | -ve | 60 |
| No. 9 | -ve | +ve | +ve | -ve | ND | -ve | -ve | 28 |
| No. 10 | +ve | +ve | +ve | -ve | ND | -ve | -ve | 65 |
No .: Number, +ve: Positive, -ve: Negative, ND: Not done
and in both the cases it was positive. All cases were negative for EMA and cytokeratin [Figure 4]. A summary of the IHC findings has been shown in Table 3.
DISCUSSION
The evaluation and categorization of adrenocortical neoplasms remain among the most challenging areas in adrenal pathology. The Weiss system, first introduced in 1984, provides specific guidelines for differentiating adrenocortical adenoma from adrenocortical carcinoma and is considered the standard for determining malignancy in tumors of the adrenal cortex.[3] Jain et al. validated the diagnostic value of the Weiss system for differentiating between benign and malignant adrenocortical tumors in a retrospective study.[4] In 1985, Van Slooten et al. developed a system based on seven histopathologic parameters, the presence of which was combined with a numeric value yielding a histopathologic index to differentiate benign from malignant tumors.[5] The threshold for malignancy was revised in 1989: the presence of three or more of the nine histopathologic criteria, as defined by the Weiss system, was considered significant for a malignant clinical behavior and it was reported as the modified Weiss system.[6] Kajor et al. stated that the conventional Weiss system appears to be the most utilized among the above-stated three distinct systems because of its simplicity and reliability.[7] We also found that the Weiss system is invaluable in determining the behavior of adrenal neoplasms.
Jain et al. also found in their study that no adenoma was larger than 5 cm and no carcinoma was smaller than 6 cm. The weight of malignant tumors in their series ranged between 57 and 1500 g, which was significantly higher compared to that of the benign tumors. They concluded that size and weight of tumor are important determinants of malignancy in an adrenal neoplasm.[4] In our study, the size of the tumors ranged between 5 and 21 cm and the weight between 350 and 1800 g. We also found that size and weight are two important parameters in adrenal tumors and to diagnose ACCs as opined by Jain et al.
Due to the rarity of ACC, large cohorts of patients for evaluation
of staging systems are not readily available. Lughezzani et al. corroborated in their study the superior accuracy of the European Network for the Study of Adrenal Tumors (ENSAT) staging system for ACC relative to the 2004 International Union Against Cancer (UICC) staging system.[8] According to Fassnacht et al., since the ENSAT classification better reflects patient prognosis than the UICC classification, its use for future clinical and research purposes is recommended.[9]
We also found that both the Weiss system and TNM staging are useful in predicting the malignant behavior and prognosis of adrenocortical carcinoma.
Even though there have been several studies for the evaluation of the Weiss system and the TNM staging system till date, we found no literature about the correlation between the two. In our study, we found that in lower stage of adrenocortical carcinoma (stages I and II), the Weiss score is low (4 — 7), while the score is high (6 — 9) when the tumor is in higher stages (stages III and IV).
Renal cell carcinoma and other histologically similar tumors are potentially confused with ACC by conventional light microscopy, and their separation from the latter is often impossible without the aid of additional studies. Two microscopic features that favor the diagnosis of RCC over ACC are the presence of glands, particularly if they contain red blood cells, and abundant cytoplasmic glycogen, but neither is pathognomonic. Immunohistochemically, strong positivity for cytokeratin, EMA, CD10, and Lewis blood group isoantigen favors RCC, whereas positivity for inhibin, A103, Melan-A, and synaptophysin favors ACC.[10]
Wick et al. studied 10 cases each of ACC, adrenocortical adenoma, and renal cell carcinoma (RCC) immunohistochemically, in an attempt to develop objective parameters which may aid in this differential diagnostic dilemma. They found that all 20 nontrypsinized adrenocortical neoplasms were positive for vimentin, but not for cytokeratin, epithelial membrane antigen, or blood group isoantigens. Conversely, each of 10 cases of RCC expressed epithelial membrane antigen, cytokeratin, and blood
Mondal, et al .: Adrenocortical carcinoma, Weiss score, immunohistochemistry
group isoantigens, but none was immunoreactive for vimentin. Two adrenocortical carcinomas and three adenomas manifested cytokeratin positivity after trypsin digestion.[11]
Renshaw et al. showed that positivity for inhibin, A103, Melan-A, and synaptophysin favors a diagnosis of adrenocortical carcinoma.[12]
Lapinski et al. stated that epithelial markers may be entirely negative in RCC, whereas pancytokeratin CAM5.2 is often positive in adrenocortical lesions. Furthermore, neuroendocrine markers are frequently positive in adrenocortical lesions. They concluded in their study that a panel of, rather than single, epithelial, “RCC-specific,” adrenocortical, and neuroendocrine markers should be applied in the differential diagnosis of RCC, adrenocortical lesions, and paragangliomas.[13]
Sangoi et al. found that for the distinction of adrenal cortical lesions from metastatic clear cell renal cell carcinoma (CC- RCC) immunoreactivity for the adrenal cortical antigens antisteroidogenic factor-1 (86% adrenal; 0% CC-RCC), calretinin (89% adrenal; 10%CC-RCC), inhibin (86% adrenal; 9% CC-RCC), and Melan-A (86% adrenal; 10% CC-RCC) and for the renal epithelial antigens antihuman kidney injury molecule-1 (0% adrenal; 83% CC-RCC), PAX-8 (0% adrenal; 83% CC-RCC), hepatocyte nuclear factor-1b (0% adrenal; 76% CC-RCC), epithelial membrane antigen (0% adrenal; 78% CC-RCC), and carbonic anhydrase-IX (3% adrenal; 87% CC-RCC) had the most potential use. They also pointed out that the use of novel renal epithelial markers antihuman kidney injury molecule-1 (clone AKG7) and/or PAX-8 and the adrenocortical marker antisteroidogenic factor-1 in an immunohistochemical panel for distinguishing adrenal cortical lesions from metastatic clear cell-RCC offers improved diagnostic sensitivity and specificity.[14]
We performed immunohistochemical analysis in all 10 cases. The results obtained in were comparable to those in the previously mentioned studies.
Aubert et al. found that the MIB-1/Ki-67 labeling index was significantly higher in malignant tumors. They stated that MIB1/Ki-67 could also help to differentiate malignant from benign adrenocortical tumors.[15] Morimoto et al. demonstrated that MIB-1 index may have prognostic relevance to predict recurrences after resection of the primary adrenocortical carcinomas.[16] In our study, all five cases showed ≥20% positivity for MIB1 (range 20 — 65%).
Our study is limited by the small number of cases in the series. The differential diagnoses of ACC include RCC, hepatocellular carcinoma, malignant melanoma, and anaplastic carcinoma of the lung and other sites.[17] The fact that we did not use a separate panel of immunomarkers for the exclusion of each of these conditions, except RCC, constituted a limitation of our study.
CONCLUSION
Our study establishes the importance of the Weiss system in diagnosing adrenocortical carcinoma. Even though modifications of this system have been suggested, the original version still remains the cornerstone for diagnosis of adrenal carcinomas. In addition to the Weiss system, we found that tumor size and weight are also important parameters in predicting malignant behavior. A correlation has been shown in this study between the TNM staging system and the Weiss system. In stages I and II of ACC, the Weiss score is low (4 — 7). In higher stages (stages III and IV), the Weiss score is high (6 — 9). Immunohistochemical analysis using a comprehensive panel of markers including vimentin, synaptophysin, Melan-A, calretinin, inhibin, EMA, CK, and Ki-67, maybe required for the confirmation of diagnosis of ACC and to differentiate it from RCC, especially because of the same tumor location.
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Cite this article as: Mondal SK, Dasgupta S, Jain P, Mandal PK, Sinha SK. Histopathological study of adrenocortical carcinoma with special reference to the Weiss system and TNM staging and the role of immunohistochemistry to differentiate it from renal cell carcinoma. J Can Res Ther 2013;9:436-41.
Source of Support: Nil, Conflict of Interest: None declared.
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