Endocrine Abstracts

JOINT21

We have experienced a case of a fifteen-year-old boy with a past history of congenital hydrocephalus and past surgeries for spina bifida and myelomeningocele, who was referred to our department for the assessment of elevated IGF-1. The patient had been receiving a regular check-up at the neurosurgery department at our hospital, and a swelling of the pituitary gland was detected during a routine brain MRI but was considered a physiological change. At the age of fifteen, he developed chest pain, and upon examination at the local hospital, anterior mediastinum tumor and elevated IGF-1 level were found. After undergoing surgery for the tumor, further investigation was conducted for elevated IGF-1 at our department. He showed no excessive height, but he had enlarged hands and feet, and protruding brow bone and lower jaw. Brain MRI identified a nodular lesion in the pituitary with a low signal on T2-weighted imaging, and endocrinological evaluation was performed with several loading tests. Oral glucose tolerance test (OGTT) showed lack of growth hormone (GH) suppression. Thyrotropin-releasing hormone (TRH) stimulation test revealed elevated serum GH concentrations, and bromocriptine stimulation test resulted in a reduction of serum GH concentrations. Additionally, LHRH stimulation test showed an exaggerated LH/FSH response. We diagnosed him with acromegaly caused by an excessive GH production from the pituitary tumor, and transsphenoidal adenomectomy was performed. Pathological examination revealed PIT1-positive tumor cells, while TPIT and SF-1 were negative. Densely granulated GH secreting cells and sparsely granulated prolactin (PRL) secreting cells were detected, leading to the diagnosis of GH/PRL secreting pituitary neuroendocrine tumor (PitNET). Three months after surgery, a follow-up OGTT was conducted, and serum GH concentration was suppressed to normal range. Although elevated GH levels in childhood often leads to gigantism, our patient had no excessive height. We presume that this was because GH elevation occurred during adolescence when his bone maturation was nearly complete. Despite the exaggerated LH/FSH response, no secretion of LH/FSH was pathologically proved in the tumor cells. High LH and FSH levels may have been due to hydrocephalus, which can cause compression of the third ventricle, leading to GnIH suppression. While there are few reports on the coexistence of PitNET with other tumors, we found no cases of PitNET occurring with mediastinum tumor. This could be a rare case, and we plan on conducting further investigations.