We describe a case of
Cushing's syndrome caused by a phaeochromocytoma secreting
corticotrophin-releasing
hormone (CRH) and
corticotrophin (
ACTH). A 49-year-old white woman presented with a 1-month history of lower limb oedema,
polydipsia and
polyuria. Physical examination revealed a patient with plethoric
facies, lanugo-type facial hair,
central obesity, red abdominal striae, lower limb oedema, and blood pressure of 210/115 mmHg. Laboratory studies showed high plasma
ACTH and markedly elevated urinary
cortisol excretion that suppressed more than 50% with high-dose
dexamethasone administration. Computed tomographic scan of the abdomen showed a 4-cm left adrenal tumour.
Catecholamines and metabolites were markedly increased in a 24-hour urine collection. Results of venous catheterization studies showed that CRH and
ACTH were secreted by the tumour. In addition, with ovine CRH administration, inferior petrosal sinus sampling showed pituitary secretion of
ACTH. Left
adrenalectomy resulted
in complete remission of
Cushing's syndrome. Light microscopic and immunohistochemical studies revealed a phaeochromocytoma that produced CRH,
ACTH and
vasopressin.
RNA studies showed that this tumour, in contrast to normal adrenal and other reported phaeochromocytomas, transcribed a lone pituitary-sized (1200
nucleotide)
pro-opiomelanocortin mRNA. This is the second reported case of a CRH-secreting phaeochromocytoma.