Context: Adrenocortical carcinomas (ACCs) are revealed in 60% of cases by steroid hypersecretion. Alternatively, it is uncommon to observe a paraneoplastic syndrome due to a peptide oversecretion.
Case description: We describe a 60-year-old man with a right adrenal mass. Hormonal evaluation showed an ACTH-independent Cushing syndrome. Surprisingly, follicle-stimulating hormone (FSH) levels were suppressed and blunted during gonadotropin-releasing hormone stimulation, despite normal luteinizing hormone levels. Levels of inhibin B, which negatively regulates the pituitary FSH, were very high. Given the atypical hormonal findings, an adrenal mass biopsy was performed, which allowed the diagnosis of an adrenocortical tumor (positive for steroidogenic factor-1 immunostaining). Moreover, an intense α-inhibin subunit immunostaining was observed. Because of the presence of metastases, the patient received mitotane and chemotherapy (etoposide and cisplatin). After 2 cycles, the inhibin B dropped. After 5 cycles, tumor size was reduced by 15%. Inhibin B levels remained low, and basal and gonadotropin-releasing hormone-stimulated FSH levels normalized. The patient underwent tumor resection, and pathology confirmed the ACC diagnosis (Weiss score of 9). The intensity of the α-inhibin subunit immunostaining was significantly decreased.
Conclusions: We report the case of an inhibin B-secreting ACC in which the response to chemotherapy and mitotane was associated with a normalization of inhibin B secretion, allowing the reversal of the blunted FSH secretion. Inhibin B should be measured in case of suppressed FSH levels despite normal luteinizing hormone levels and may be considered a tumoral marker in some ACCs, even during treatment follow-up.
Keywords: adrenocortical carcinoma; inhibin B; tumor marker.