Plurihormonal pituitary neuroendocrine tumor causing acromegaly with subclinical Cushing’s disease

ABSTRACT Macrosomatotropinoma is the most common cause of acromegaly. Plurihormonal pituitary neuroendocrine tumor causing acromegaly often has growth hormone (GH) and prolactin excess. Here, we present a case of acromegaly with adrenocorticotrophic hormone (ACTH) excess due to macrosomatocorticotropinoma. A 32 years old man presented with left-sided progressive painless loss of vision. Clinically, he had acromegaloid features with overt diabetes mellitus (DM) without any discriminatory features of Cushing’s disease or hypertension. The hormonal evaluation revealed elevated insulin-like growth factor 1 with nonsuppressible GH and elevated plasma ACTH. Overnight, the dexamethasone test was nonsuppressible but the low-dose dexamethasone test was suppressible. Magnetic resonance imaging showed pituitary macroadenoma with optic chiasmal compression. Perimetry revealed left anopia. He underwent endoscopic transnasal transsphenoidal resection of macrosomatotropinoma with full recovery of vision. Immunohistochemistry confirmed pleurihormonal (GH and ACTH) pituitary adenoma. Postoperatively, his secondary DM is well controlled on oral antidiabetic agents. He underwent gamma knife surgery for residual lesion and is presently on long-acting somatostatin receptor ligand octreotide for active acromegaly. This is an extremely rare case of overt acromegaly with subclinical Cushing’s disease due to plurihormonal macrosomatocorticotropinoma. A total of 25 similar cases have been recorded in world literature to date. In the presence of GH–ACTH excess, signs of acromegaly are often clinically dominant and Cushing’s disease is usually but not always silent.