Immunohistochemical staining of normal, hyperplastic, and neoplastic adrenal cortex with a monoclonal antibody against alpha inhibin.

Abstract

Aims-To investigate the immunohistochemical staining of normal, hyperplastic, and neoplastic adrenal cortex with a monoclonal antibody against inhibin. Also, to determine whether immunostaining with this antibody is useful in diVerentiating between adrenal cortical neoplasms and other tumours involving the adrenal gland that might mimic them. Methods-Normal adrenal tissue (n = 20) and specimens from cases of adrenal hyperplasia (n = 13), adrenal cortical adenoma (n = 15), adrenal cortical carcinoma (n = 4), phaeochromocytoma (n = 8), and adrenal metastatic tumour (n = 7) were stained with a monoclonal antibody against the subunit of human inhibin. Results-Positive staining with the antiinhibin monoclonal antibody was seen in all normal adrenal glands. Immunoreactivity was largely confined to the inner cell layers of the adrenal cortex, with no staining of the adrenal medulla. All hyperplastic adrenal glands and adrenal cortical adenomas and carcinomas were also immunoreactive. The other tumours studied were negative. Conclusions-There is consistent immunoreactivity with the anti-inhibin monoclonal antibody in normal adrenal cortex and in hyperplastic and neoplastic adrenal cortical lesions. In the normal adrenal cortex, positive staining is mainly confined to the zona reticularis. Other neoplasms involving the adrenal gland are negative. Immunohistochemical staining with anti-inhibin monoclonal antibody, performed as part of a panel, may prove to be of value in the distinction between adrenal cortical carcinoma and phaeochromocytoma or metastatic tumour. (J Clin Pathol 1998;51:114-116)

Expression of inhibin alpha in adrenocortical tumours reflects the hormonal status of the neoplasm

“…Both inhibin and subunit mRNA species and peptides can be detected in adrenal cortex, but not in the medulla (Meunier et al 1988, Voutilainen et al 1991, Spencer et al 1992, McCluggage et al 1998. The first reports suggested all adrenocortical tumours to be inhibin positive (Chivite et al 1998, McCluggage et al 1998.…”

“…The first reports suggested all adrenocortical tumours to be inhibin positive (Chivite et al 1998, McCluggage et al 1998. Later reports, however, showed equal amounts of immunonegative and immunopositive adrenocortical tumours (Renshaw & Granter 1998).…”

“…Steroid-producing organs, pituitary gland, placenta and the central nervous system are the main sites of inhibin subunit gene expression (Meunier et al 1988, Voutilainen 1995. In humans, inhibin subunit gene is expressed in both foetal and adult adrenal cortex (Voutilainen et al 1991, Spencer et al 1992, and the inner zones, particularly the zona reticularis, have the strongest immunoreactivity with anti-inhibin antibody (Chivite et al 1998, McCluggage et al 1998. The role of adrenal inhibins is not fully understood.…”

“…Inhibins have been suggested to have a tumour suppressor role for the adrenal gland, since gonadectomized inhibin-deficient mice develop adrenocortical tumours (Matzuk et al 1992). Recently two papers reported immunoreactivity against inhibin in adrenocortical tumours (Chivite et al 1998, McCluggage et al 1998. Further studies discovered a considerable number of adrenocortical tumours exhibiting no immunostaining for inhibin (Pelkey et al 1998, Renshaw & Granter 1998.…”

Myxoid adrenal adenoma with focal pseudoglandular pattern

“…The vast majority of adrenal tumors also stain positively for inhibin. [12] A103 is a monoclonal antibody directed against an antigen on melanoma cells recognized by T lymphocytes termed melan A or MART-1.5 Although this antibody has been most commonly used as a marker for malignant melanoma, it has also been proved to be positive in adrenocortical tumors. [13] Vimentin is commonly expressed in adrenal tumors and was positive in our case.…”