A case of silent ACTH/GH adenoma
Pawan Pusalkar1, Sunil Zachariah1, Azraii Nasruddin1, David Russell-Jones1 & Federico Roncaroli2
A 34-year-old male presented in March 2006 to the eye department with reduced visual acuity in left eye over 2 months and was initially diagnosed as retrobulbar neuritis. His vision was not improving in the next 2 months and so an MRI of the optic nerve was arranged which revealed a pituitary tumour impinging on the optic chiasma and his visual fields showed an early bitemporal hemianopia. Initial bloods revealed T4 13.5 pmol/l, TSH 1.4 μ/l, cortisol 305 nmol/l, prolactin 376 μ/l, testosterone 8 nmol/l. He was referred for an urgent neurosurgical intervention. He did not have any features of hormonal excess, but his visual field defect worsened in the next few months. He had a transphenoidal resection of the tumour in Jan 2007. The biopsy of the tumour revealed that 90% of the neoplastic cells expressed ACTH and GH. Immunoreaction for the other pituitary hormones was negative. Crookes hyaline change was also noted on microscopy. These changes are exceedingly uncommon in silent ACTH lesions (Roncorli et al. Endocr Pathol 2002 13 245-249)
Post operative insulin tolerance test confirmed cortisol deficiency and the need for long term hydrocortisone replacement, but ruled out any evidence of severe GH deficiency.
Conclusion: This is a very unusual case as only 3 silent ACTH/GH adenomas have been reported, all presenting with pituitary apoplexy (Abe et al. Acta Neuropathologica 2001 102(5) 435440), but none of these patients showed coexpression of the 2 hormones in the same tumour cells as with our patient.