ESPE Abstracts

Background: Silent corticotroph adenomas are adenomas composed of corticotrophs but are different from corticotroph adenomas. Despite being silent, they show more aggressive behavior than other clinically nonfunctional adenomas. Adrenocortical choristomas in silent corticotroph adenomas (i.e. the presence of adrenocortical cells in the heterotopic location of the sella) were reported in three patients 16 years or older until now.

Objective: Here we report, to our knowledge, the fourth and the youngest case of silent corticotroph adenoma with adrenocortical choristoma.

Case report: The patient had been receiving L-thyroxine treatment and was on follow-up for compensated hypothyroidism (exaggerated TSH response to TRH) since four months of age. At 11 years, despite L-thyroxine treatment, findings compatible with secondary hypothyroidism (low free T4 and low TSH) was found. Cortisol was also low (4.82 ug/dl) and ACTH was not elevated (11.78 pg/ml). Physical examination was unremarkable except the presence of double urethral meatus. On MRI, a 11×11×10 mm lesion in the pituitary region which contrasted later than the pituitary gland was found to be primarily suggestive of an adenoma. Before the patient underwent adenomectomy, ACTH deficiency was confirmed with a peak cortisol of 15.27 ug/dl to low-dose ACTH and cortisol replacement was added to L-thyroxine replacement. Pathological evaluation revealed the presence of two types of cells in the excision material:Small cells which express ACTH and larger cells rich in mitochondria which are similar to adrenocortical cells and which do not secrete any of the pituitary hormones. Pathological diagnosis was ACTH expressing pituitary adenoma and adrenocortical choristoma.

Conclusion: The lack of biochemical and clinical evidence of Cushing syndrome despite ACTH expressing cells in the adenoma indicated the presence of a silent adenoma. The presence of a second group of cells similar to adrenocortical cells in this heterotopic location is compatible with choristoma. The younger age of our patient than those of previously reported cases and clinical significance of silent corticotroph adenoma in general make this case of rare entity more remarkable.