On paraneoplastic cushing in prostatic neuro-endocrine carcinoma: A case report

ABSTRACT

Background: Cushing syndrome associated with neuro-endocrine carcinoma of prostate is a rare and difficult diagnosis cause of paraneoplastic syndrome. This is partly due to the rarity of neuroendocrine prostate cancer (less than 1% of prostate cancers) and that the extra-pulmonary location of neuroendocrine tumours is less known. This can lead to a delay in diagnosis. Case presentation A 58-year-old man was admitted for sudden muscle weakness in the context of an infection with Sars-cov2. The systematic history did not highlight any other complaint. His physical examination revealed swollen legs with godet sign and symmetrical proximal strength deficit. The rest of the clinical examination was unremarkable. The patient is known for a total radical prostatectomy in the context of a neuro-endocrine carcinoma with small cells of the prostate with multiple metastasis. His chronic treatment consisted of alizapride, metoclopramide and lormetazepam. Initial blood testing revealed an anemia with lymphopenia and eosinopenia, hypokaliemia (2.3 mmol/l), hypo-proteinemia, high level of LDH. CRP and creatinine were within standards. In the light of his muscle weakness, severe hypokaliemia refractory to IV KCl high dose and oncological history, a cushing syndrome was suspected. Which was confirmed with cortisoluria (31,272.1 nmol/24 h) and a high level of serum ACTH (582 pg/ml). An ACTH adenoma was reasonably excluded by a pituitary-MRI. With all of these elements, we conclude at a paraneoplasic cushing syndrome arising of a recidivism of his prostatic neuro-endocrine carcinoma. Discussion(s) In a neoplasic contexte with none pituitary adenoma, the ACTH-dependent cushing syndrome is due to an ectopic secretion of ACTH (rarely CRH) in a context of paraneoplasic syndrome. Patients with suggestive signs or symptoms should alert us as complications of cushing syndrome are fatal by an increased cardiovascular risk, a prothrombophilic state, suicidal ideation and immunosupression. In our patient's case, the clinic was poor because of the rapidity with which the pathology sets in, and the blood test was the most evocative. It can also be the point of call for the fortuitous discovery of a neoplasia of the neuro-endocrine or carcinoid type. We rely on cortisoluria or the short dexamethasone test and the ACTH to suspect the diagnosis. If there is any doubt about the neoplastic origin or in the absence of a history, an octreotide scan can be performed to locate the ectopic secretion of ACTH. Cancer treatment remains the main therapy. With regard to the actual treatment of the cushing syndrome, there is debate. We can inhibit steroid production (ketoconazole, metyrapone, etomidate, ...) or make bilateral adrenalectomy (surgery, mitotane). Conclusion(s) The paraneoplastic cushing syndrome may be difficult in early state with just some aspecific abnomalies at the blood testing. In our case, the patient initially had only hypokalemia associated with proximal muscle weakness. We must keep in mind that Cushing's syndrome is a fatal disease. Increased cardiovascular risk, hypertension and prothrombotic state are the major causes of death associated with cushing syndrome. Hypoproteinemia leading to a decrease in immune defences leads to severe infections and even septic shock.