Objective: To investigate the potential diagnostic value of A103 and inhibin-alpha in adrenocortical tumors and to evaluate the applicability of tissue microarray/tissue chip in pathological studies using immunohistochemistry.
Methods: A tissue microarray/tissue chip was constructed to contain 179 formalin-fixed, paraffin-embedded adrenal tissue samples which include 3 normal adrenal cortex, 2 fetal adrenal cortex, 2 nodular adrenocortical hyperplasia samples, 72 adrenocortical adenomas, 39 adrenocortical carcinomas, 3 adrenal medulla, 13 metastatic carcinomas, 4 metastatic malignant melanomas and 44 pheochromocytomas. Additional 20 cases of normal adult adrenal gland were used as controls. Immunohistochemical markers, including A103, inhibin-alpha, calretinin and Ki-67 were used on the tissue array sections by EnVision immunohistochemical staining methods.
Results: Positive staining of A103 was seen in all of the 23 (100%) adrenal cortex, 2 fetal adrenal cortex, 2 nodular adrenocortical hyperplasia samples, 60 of 66 (90.9%) adrenocortical adenomas samples, 35 of 37 (94.6%) adrenocortical carcinomas samples, 3 of 3 malignant melanomas, but in none of the adrenal medulla, pheochromocytomas or adrenal metastatic carcinoma samples. In all of the adrenal cortex, fetal adrenal cortex and nodular adrenocortical hyperplasia cases, inhibin-alpha immunoreactivity was limited to the zona reticularis and the innermost zona fasciculata. Fifty of the 66 (75.8%) adrenocortical adenomas, 28 of the 37 (75.7%) adrenocortical carcinomas were positive for inhibin-alpha. None of the adrenal medulla, pheochromocytoma, metastatic malignant melanoma or carcinoma samples showed a positive inhibin-alpha immunostain.
Conclusions: The tissue microarray/tissue chip technique provides a reliable method to investigate marker expression by offering a rapid, economic and accurate screening of tissue specimens on a large scale. The combined use of A103 and inhibin-alpha is valuable in distinguishing adrenocortical tumor from pheochromocytoma and other metastatic neoplasms.