Endocrine Abstracts

Introduction: The small-cell neuroendocrine prostate carcinoma (SCPC) is rare, highly aggressive and usually transforms from prostate adenocarcinoma (PAC) after androgen deprivation therapy (ADT).

Case Report: A 66-year-old man had a three-year history of high-grade PAC with high burden disease (abdominal lymph node and bone metastasis) at presentation (09/2019). On the initial staging evaluation, the CT scan documented a 20 mm left adrenal nodule compatible with adenoma. No assessment for hormone excess was performed. He initiated long-term ADT and completed six cycles of palliative chemotherapy with docetaxel. He had good clinical, biochemical (PSA decreased from 18.84 to less than 1 ng/ml) and imaging responses on conventional exams, with best response stable disease. Nineteen months after diagnosis, the left adrenal nodule grew to 29 mm and a de novo 13 mm right adrenal nodule was documented. After additional seven months, dimensional progression (on the left to 46 mm; on the right to 17 mm) and features suspicious for malignancy were observed. An MRI confirmed bilateral adrenal metastasis with further progression after six months (on the left to 50 mm; on the right to 45 mm). Analytically there was evidence of hypocortisolism, and the Endocrinology Department was consulted. Clinically he complained of moderate asthenia, anorexia, and low normal blood pressure for four months. On physical examination was noted mucocutaneous hyperpigmentation and the blood pressure was 110/70 mmHg. Further endocrine studies confirmed primary adrenal insufficiency: morning cortisol 6.7 µg/dl, ACTH 765.80 pg/ml, unmeasurable DHEA-s and aldosterone, high plasma renin activity; normal-high potassium; normal sodium and fasting glucose. Functional pheochromocytoma was excluded. He was started on hydrocortisone at supraphysiological doses, with marked clinical improvement. The 18F-FDG PET/CT revealed enlarged nodular adrenal glands with moderate tracer uptake and slight prostate heterogeneous tracer uptake, with no other abnormal foci. The adrenal mass biopsy revealed a small-cell neuroendocrine carcinoma; immunohistochemical staining was positive for CK AE1/AE3, synaptophysin, chromogranin and PSA (negative for CK7, CK20, MelanA and TTF1); Ki67 > 50%. It was decided to start cisplatin and etoposide.

Discussion: We describe an exceptional rare case of bilateral adrenal metastasis causing adrenal insufficiency, from a prostate cancer that possibly transformed from PAC to SCPC after ADT. Indeed, adrenal insufficiency is uncommon in the context of bilateral adrenal metastasis and the adrenal glands are unusual sites of metastatic prostate cancer. The SCPC usually presents mixed with classic PAC and carries a poor prognosis with rapid disease progression and limited survival.