Histopathological and immunophenotypic features of testicular tumour of the adrenogenital syndrome

Aims: Testicular tumour of the adrenogenital syndrome (TTAGS) is a rare neoplasm histologically resembling Leydig cell tumour (LCT). We report six cases of TTAGS and analyse histopathological and immunophenotypical features that distinguish TTAGS from LCT. Methods and results: Six cases of congenital adrenal hyperplasia with bilateral TTAGS were examined histologically and immunohistochemically and compared to seven cases of testicular LCT. TTAGS was characterized histologically by sheets of polygonal cells separated by dense fibrous tissue with focal lymphocyte infiltration. All cases of TTAGS lacked cytological atypia except for one, which displayed scattered large pleomorphic, nuclei with one or two prominent nucleoli and sporadic mitotic figures. Immunohistochemically, all cases of TTAGS showed diffuse and strong positivity for CD56 and negative reactivity for androgen receptor. Reactivity for synaptophysin varied from focal (five cases) or diffuse (one case). In contrast, LCT displayed focal weak to moderate or negative reactivity for CD56 and focal weak or negative reactivity for synaptophysin, but positive reactivity for androgen receptor in six of seven cases. Conclusions: In addition to clinical information, biochemical profile and histopathological findings, our results suggest that immunohistochemistry using a panel of antibodies including CD56, synaptophysin and androgen receptor is helpful in differentiating TTAGS from LCT.