Endocrine Abstracts

Background

Silent somatotroph pituitary tumours are very rare, representing only 2-4% of all pituitary tumours in surgical series. Little is known about the course of the disease and efficacy of possible treatment modalities.

Presentation of the case

A male, born in 1990, was first admitted to the hospital at the age of 15, due to sudden ptosis of the right eye and headaches, present for 1 year before the diagnosis. Magnetic resonance imaging (MRI) of the head revealed a solid, homogeneous tumour in the Turkish saddle, 47x37x37 mm in diameter, described as slightly hyperintense in T2- images and FLAIR sequences, slightly hypointense in T1- images and homogeneously enhancing after contrast administration. The tumour expanded into the sphenoid sinuses, medial part of the left cavernous sinus and filled completely the right cavernous sinus, surrounding the whole circumference of the right internal carotid artery. It compressed the right temporal lobe, hypothalamus and the optic chiasm. The patient underwent a transsphenoidal partial resection of the pituitary tumour, with histopathological confirmation of pituitary neuroendocrine tumor (PitNET) with features of nuclear atypia. Immunohistochemistry was positive for growth hormone (GH), +/- for prolactin, negative for the remaining pituitary hormones, MIB1 10%. In electron microscope images, silent somatotroph, sparsely granulated PitNET was confirmed. Neither before surgery nor during 16-year observation did the patient present any clinical symptoms of acromegaly. Upon diagnosis, full endocrinological evaluation was not performed, however, Insulin-like Growth Factor-1 (IGF-1) concentrations were within the normal range, with elevated GH levels and no suppression in the oral glucose tolerance test. Medical treatment with long-acting somatostatin analogue was introduced. Since the surgery, the patient underwent both endocrinological and neurosurgical assessment regularly. Over time MRI images were stable: in the last MRI performed in 2019 a partially empty sella was described, with the invasion of right cavernous sinus by a 20x32x25 mm lesion surrounding the right internal carotid artery. Endocrinological follow-up revealed secondary hypothyroidism and proper function of the gonadal, adrenal and somatotroph axis, with normal concentrations of prolactin and no clinical nor biochemical symptoms of diabetes insipidus. No visual field deficits were discovered during ophthalmological examination.

Conclusion

Although antiproliferative effect of somatostatin analogues has been reported, very little data concerting silent somatotroph pituitary tumours and the treatment options is currently available. Further multicentre studies are needed to investigate the course of those very rare pituitary tumours and create the standards of treatment.