Endocrine Abstracts

Background: Oncocytic neoplasms are rare adrenal tumours usually considered as benign and non-functional. Conversely, in recent large nationwide study from COMETE network over 50% of the oncocytic adrenocortical tumours were diagnosed as carcinoma according to Lin Weiss-Bisceglia-score. However, until now only 11 cases of metastatic oncocytoma were reported in English literature.

Case report: A 54-year-old man with history of abdominal pain and weight loss (18 kg in 12 month) was diagnosed with left adrenal mass in 2014. In March 2016, hormonal evaluation showed that the tumour was non-functional. Left adrenalectomy with simultaneous nephrectomy were performed in another centre. The pathological examination revealed a 23×13×9 cm tumour. Initial histological analysis was in favour of a benign oncocytic adenoma with no Weiss criteria for malignancy, without kidney invasion. There was no further follow-up, no thoracic imaging. Postoperatively, the patient developed end-stage renal failure because right kidney was non-functional (which unfortunately had not been checked preoperatively) and required haemodialysis. Hydrocortisone supplementation was stopped in June 2016. In June 2018, the patient was referred to our centre (Felix Guyon University Hospital). Abdominal and thoracic CT-scan showed two pulmonary nodules (2.8 cm and 0.8 cm, in left and right lower lobes, respectively). 18F-FDG PET/CT imaging showed intense 18F-FDG uptake of pulmonary lesions. Pathologic examination of the CT-guided percutaneous needle biopsy showed large tumour cells with eosinophilic granular cytoplasm, diffuse architecture and nuclear atypia. There was no mitosis; central zone of necrosis was noted. Immunohistochemistry confirmed the adrenocortical origin with positivity for synaptophysin, cytokeratin-8/18, melan-A, MART1 and α-Inhibin-A and no expression of chromogranin-A. Adrenal tumour samples from 2016 were reviewed by two independent pathologists (one of them belonging to a national reference centre) who concluded to malignant adrenal oncocytoma with two major criteria of malignancy (mitotic rate 6/40 high power field, atypical mitoses) and at least 1 minor criteria (size >10 cm) according to Lin–Weiss–Bisceglia score. Ki67 was 8%. Immunohistochemistry showed positivity for synaptophysine, cytokeratin-8/18, melan-A and MART1 but no expression of α-Inhibin-A, chromogranin-A. The patient underwent radiofrequency ablation of metastatic pulmonary lesions (Paris). A low dose of mitotane treatment (1500 mg/d) was introduced due to renal impairment. Mitotane dose was progressively increased to 3000 mg/d. Mitotane serum level was stable before and after haemodialysis which suggests that it is not dialyzable. Short-term evolution was eventless.

Conclusion: Oncocytic adrenocortical carcinoma are rare tumours with potent metastatic evolution. They should be managed by a multidisciplinary expert team.