Ectopic adrenocorticotropic hormone syndrome caused by metastatic carcinoma of the prostate: therapeutic response to ketoconazole

Molecular analysis and literature-based hypothesis of an immunonegative prostate small cell carcinoma causing ectopic ACTH syndrome

Ectopic ACTH syndrome (EAS) due to a prostate small cell carcinoma (SCC) is very rare with only 26 cases reported to date and has a poor prognosis. We here describe another case of this disorder that was clinically typical based on prior reports as it showed hypercortisolemia and severe hypokalemia with multiple metastasis. However, our current case of prostate SCC causing EAS is the first to display negative immunostaining for ACTH despite detectable POMC mRNA expression in the primary lesion. ACTH immunonegativity is thought to be associated with a more aggressive disease course and a poorer prognosis although there are few studies of the underlying mechanisms. We explored two possibilities for this finding in our current patient: aberrant POMC processing prevented immunodetection with an anti-ACTH antibody; and the ACTH content per cell was below the threshold for immunodetection due to its rapid secretion or low synthesis. The aberrant processing theory was thought to be less likely because of immunonegative findings even using anti-POMC/ACTH antibodies. As the plasma ACTH levels in our patient were comparable with those reported for previous immunopositive prostate EAS cases, we speculated that the depletion of ACTH may be caused not only by rapid secretion but also by low production levels as a sign of de-differentiation. De-differentiation may therefore explain the mechanism underlying the negative correlation between immunoreactivity for ACTH in EAS and disease aggressiveness. We believe that our present findings will be of use in future prospective studies aimed at confirming the mechanism of immunonegativity.

Severe Cushing's syndrome due to small cell prostate carcinoma: a case and review of literature

Cushing's syndrome (CS) due to ectopic adrenocorticotrophic hormone (ACTH) is associated with a variety of tumours most of which arise in the thorax or abdomen. Prostate carcinoma is a rare but important cause of rapidly progressive CS. To report a case of severe CS due to ACTH production from prostate neuroendocrine carcinoma and summarise previous published cases. A 71-year-old male presented with profound hypokalaemia, oedema and new onset hypertension. The patient reported two weeks of weight gain, muscle weakness, labile mood and insomnia. CS due to ectopic ACTH production was confirmed with failure to suppress cortisol levels following low- and high-dose dexamethasone suppression tests in the presence of a markedly elevated ACTH and a normal pituitary MRI. Computed tomography demonstrated an enlarged prostate with features of malignancy, confirmed by MRI. Subsequent prostatic biopsy confirmed neuroendocrine carcinoma of small cell type and conventional adenocarcinoma of the prostate. Adrenal steroidogenesis blockade was commenced using ketoconazole and metyrapone. Complete biochemical control of CS and evidence of disease regression on imaging occurred after four cycles of chemotherapy with carboplatin and etoposide. By the sixth cycle, the patient demonstrated radiological progression followed by recurrence of CS and died nine months after initial presentation. Prostate neuroendocrine carcinoma is a rare cause of CS that can be rapidly fatal, and early aggressive treatment of the CS is important. In CS where the cause of EAS is unable to be identified, a pelvic source should be considered and imaging of the pelvis carefully reviewed.

Unusual cause of ectopic secretion of adrenocorticotropic hormone: Cushing syndrome attributable to small cell prostate cancer

OBJECTIVE

To report a rare cause of ectopic adrenocorticotropic hormone (ACTH) secretion leading to severe Cushing syndrome.

METHODS

We describe the clinical presentation and management of a case of Cushing syndrome attributable to ectopic ACTH secretion from small cell cancer of the prostate.

RESULTS

In a 70-year-old man with hypertension and diabetes, congestive heart failure developed. He was found to have severe hypokalemia (serum potassium, 1.7 mEq/L) and a huge pelvic mass on a computed tomographic scan performed because of a complaint of urinary retention. Transurethral biopsy of the prostate showed features of small cell prostate cancer. Hormonal evaluation revealed a high urine free cortisol excretion of 6,214.5 microg/d (reference range, 36 to 137), confirming the diagnosis of Cushing syndrome. A serum ACTH level was elevated at 316 ng/dL (reference range, 10 to 52). An overnight high-dose (8 mg orally) dexamethasone suppression test was positive (serum cortisol levels were 43.2 and 41 microg/dL before and after suppression, respectively), and magnetic resonance imaging of the pituitary gland disclosed no abnormalities. A prostate biopsy specimen showed small cell prostate cancer with positive staining for ACTH. The tumor was found to be unresectable, and the poor condition of the patient did not allow for bilateral adrenalectomy. He was treated with ketoconazole and metyrapone, which yielded good temporary control of his Cushing syndrome (24-hour urine free cortisol decreased to 55.2 microg/d). He received 1 cycle of chemotherapy (etoposide and cisplatin), but he died 6 months later as a result of sepsis.

CONCLUSION

Small cell prostate cancer is a rare subtype that can be associated with ectopic secretion of ACTH and severe Cushing syndrome. With this subtype of prostate cancer, Cushing syndrome should be considered and appropriately managed.

Cushing's syndrome due to ectopic ACTH production by (neuroendocrine) prostate carcinoma

Ectopic adrenocorticotropin (ACTH) secretion accounts for less than 10% of all causes of endogenous Cushing's syndrome (CS) and is usually associated with neuroendocrine tumors and small cell carcinoma of the lung. We report the case of a 62-year-old man with CS due to ectopic ACTH production by small cell carcinoma of the prostate. He presented with severe hypercortisolism and associated symptoms. Plasma neuron specific enolase (NSE) was grossly elevated. Despite performing a laparoscopic bilateral adrenalectomy, the patient died as a result of sepsis with multi-organ failure. Post-mortem immunohistochemical staining of prostate tumor tissue showed ACTH expression. ACTH staining was also performed in four additional patients with small cell carcinoma of the urinary tract without CS. None of these additional cases showed a positive staining for ACTH. Although a rare cause of ectopic ACTH production, neuroendocrine prostate carcinoma should be considered in male patients with Cushing's syndrome, in particular in those with an occult source of ACTH overproduction.

Cushing syndrome associated with prostatic tumor adrenocorticotropic hormone (ACTH) expression after maximal androgen blockade therapy

We report a patient with adenocarcinoma of the prostate, who eventually developed Cushing syndrome due to ectopic adrenocorticotropic hormone (ACTH) secretion from the tumor. At first, maximal androgen blockade (MAB) therapy was effective for the prostate carcinoma, which was positive for prostate-specific antigen (PSA) and negative for ACTH on the biopsy specimen. However, 3 years later, the patient complained of bilateral leg edema. A chest computed tomographic (CT) scan showed bilateral pleural effusion and inflammatory changes, focused on the right upper-lobe. While his PSA was not elevated, and there were no obvious tumor metastases, his serum cortisol and ACTH levels were elevated, without any evidence of lesions that could release ectopic ACTH. Two weeks later, the patient complained of dyspnea and bilateral pleural effusion, and inflammatory changes were worse. Although the patient was administered inhibitors of adrenocorticoid synthesis-metyrapone, they did not have enough clinical efficiency. Steroid pulse therapy was also administered but the patient's severe pneumonia and pleural effusion did not improve and he finally died of respiratory failure. In contrast to the initial biopsy specimen findings, on autopsy, the tumor was negative for PSA but positive for ACTH. Thus, it would appear that the tumor began to produce and release ectopic ACTH after therapy, which resulted in the development of Cushing syndrome in this patient with prostate carcinoma.