Long-standing acromegaly in a patient with a pituitary adenoma not visible on MRI Case report

Abstract

Introduction: Acromegaly in the course of a pituitary microadenoma or neuroendocrine GHRH-secreting tumour (GHRH, growth hormone-releasing hormone) invisible on MRI is very rare.

Objective: To present the difficulties in determining the cause behind an excessive production of the growth hormone in a patient suffering from long-standing acromegaly, without a pituitary focal lesion that would be visible on MRI.

Case report: The authors describe a case of a 69-year-old female with acromegaly, diagnosed 22 years earlier based on the typical somatic symptoms, and confirmed by the elevated concentration of insulin- like growth factor type 1 and lack of growth hormone suppression in the oral glucose tolerance test. The initial MRI scan (1994) had revealed a hypoechogenic 2 x 3 mm lesion in the anterior lobe of the pituitary gland, whose presence was not reported in the subsequent MRI tests. As ectopic GHRH or growth hormone secretion was suspected, a neuroendocrine tumour was searched for. The 47.7 × 54 × 35.7 mm tumour, located in the thoracic outlet, accumulating tektreotide in receptor scintigraphy, turned out to be a nodular goitre on histopathology. Due to the undetermined location of the source of growth hormone overproduction, failure to measure GHRH levels, and the patient’s lack of consent to undergo sella turcica exploration, long-acting release octreotide had been used for many years to manage the patient’s condition.

Conclusion: The long-lasting and ineffective search for a neuroendocrine tumour producing GHRH or growth hormone as well as the absence of a focal lesion in the repeated MRI scans render it impossible to unequivocally determine the cause of the patient’s acromegaly, and illustrate the difficulties in discovering the source of growth hormone overproduction.