Inhibin/activin subunits are immunohistochemically expressed in complete and partial hydatidiform moles

Inhibins are dimeric glycoproteins, belonging to the transforming growth factor beta (TGF-beta) family, composed of an alpha-subunit (INH-alpha) and one of two possible beta-subunits (betaA or betaB). Additionally two further beta-subunits (betaC and betaE) have been cloned, although their function remains still quite unclear. The detection by immunohistochemistry of inhibin/activin subunits has been proposed as a useful marker of trophoblastic diseases. Interestingly, a complete mole cannot be easily differentiated from a partial mole. Therefore, the aim of this study was to determine expression changes of the five inhibin/activin subunits in partial and complete moles.

Histologically diagnosed complete (n = 6) and partial (n = 3) hydatidiform moles were immunohistochemical analyzed for INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits. The immunohistochemical reaction in intermediate trophoblast was analyzed with a semiquantitative score (IRS) and statistical analysis was performed.

Immuno-histochemical reaction with INH-alpha, INH-betaA, INH-betaB, INH-betaC and INH-betaE subunits was demonstrated in hydatidiform moles. The INH-betaA and INH-betaB expression was significantly higher in complete compared to partial moles (p < 0.05 each), while INH-alpha, INH-betaC and INH-betaE did not demonstrate any statistically significant differences.

We demonstrated an immunohistochemical expression of all five inhibin/activin subunits in partial and complete hydatidiform moles. The expression of INH-betaA and INH-betaB determined immunohistochemically was significantly up-regulated in complete moles, suggesting the utilization of these antibodies as diagnostic differentiation markers between complete and partial moles.