Primary rhabdoid adrenocortical carcinoma: a clinicopathological and immunohistochemical study of three cases

AIMS: We describe three cases of primary adrenocortical carcinoma (ACC) with prominent rhabdoid features and study their clinicopathological and immunohistochemical properties. METHODS AND RESULTS: The patients were three females aged 45-55 years (mean 49 years), none of whom had any hormone-related symptoms. Histologically, the characteristic features were rhabdoid tumour cells with prominent eosinophilic cytoplasmic inclusions, eccentric vesicular nuclei and prominent nucleoli. Areas of more conventional ACC were present in all cases. Immunohistochemically, the rhabdoid component showed a similar staining pattern to conventional ACC, being positive for steroid receptor cofactor 1, inhibin, melan A, calretinin and synaptophysin, while negative for high molecular weight cytokeratin and Pax8. In addition, antimitochondrial antibodies showed a weak reaction and nuclear expression of integrase interactor 1 (INI1) was preserved. Clinical follow-up information for two patients demonstrated that one patient was alive 237 months after diagnosis, and one patient had died of disease 4 months after diagnosis. CONCLUSIONS: ACC with rhabdoid features are rare tumours that seem to mirror the clinical and immunohistochemical features of conventional ACC. In addition, they appear to display similar biological behaviour. Adrenocortical carcinoma should be included in the differential diagnosis when evaluating tumours of unknown origin with rhabdoid morphology.