Microscopic images of Adrenocortical carcinoma
Adenocarcinoma of the adrenal cortex is rare , with an incidence of 1:1700000 population or 0.02% of cancers.
It has a bimodal age distribution of 10-20 and 40-60, with equal male and female incidence.
Patients with carcinoma of the adrenal cortex usually have endocrine manifestations -feminization and masculinization are pointers to malignancy in adrenal cortical neoplasia.
Most adrenal carcinomas are large with average weights in reported series in the range 750-1500g, and many tumors are larger. There is often obvious local spread or metastasis at operation.
Weiss (1984) described the histological features present in more than 50% of 18 metastasizing/recurring adrenal cortical tumors.
These included : high nuclear grade (III or IV), mitotic rate over 5 per 50 hpf, compact cells comprising more than 75% of the tumour, diffuse architecture, tumour necrosis and invasion of sinusoidal structures and/or of the capsule.
It is worth noting that in this study (Weiss 1984): the three features found only in metastasizing or recurring tumours were mitotic count of over 5 per 50 hpf, atypical mitoses and invasion of venous structures.
These features, when present, should therefore be regarded as absolute indicators of malignancy.
The problem is that not all adrenal cortical adenocarcinomas have one or more of these features.
It is inevitable that in a number of adrenal cortical tumours no secure prediction of behavior can be made and the term "adrenal cortical tumour of uncertain malignant potential" may be appropriate.
Long term follow up of these may be desirable because although adrenal cortical adenocarcinoma is usually virulent with reported overall mortality between 79% and 92%, the malignant nature of some tumours can take 10 years to become apparent.
Nuclear DNA content has been advocated as a predictor of malignancy in adrenal cortical neoplasia, but not all adenocarcinomas are aneuploid.
In contrast to the findings with many other tumours, Haak et al (1993) found longer survival in patients with aneuploid than with diploid tumours.
DNA ploidy combined with morphometric indicators of nuclear pleomorphism and tumour weight have been proposed for prediction of malignancy in discriminant analysis, but overlap was found in the features of benign and malignant tumours.
Examination of silver binding nucleolar organizer regions (Ag-NOR) has been advocated for prediction of malignancy, with carcinomas having significantly higher Ag-NOR counts than adenomas in one study.
The differential diagnosis of adrenal cortical adenocarcinoma includes other clear cell tumors such as hepatocellular and renal cell carcinomas -immunohistochemistry for cytokeratin types has been advocated as a means of distinguishing these entities.
Neuroendocrine differentiation, as evidenced by immunohistochemical detection of synaptophysin and neurone "specific" enolase, detection of synaptophysin mRNA, and by electron microscopy, is encountered in some adrenal cortical tumours including carcinomas.
Electron microscopy is valuable in differential diagnosis of adrenal cortical adenocarcinoma for other similar appearing tumours, but there are no specific features indicative of malignancy.
Adrenal cortical carcinoma with extension into the inferior vena cava – case report and literature review
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