Endocrine Abstracts

A 23-year-old woman was diagnosed with neurofibromatosis type 1 (NF-1) at the age of 7 years. She presented with café au lait patches, axillary freckling, Lisch nodules, and plexiform neurofibromas on her left cheek and in the left paraspinal muscles. Genetic testing confirmed the PV c.7348C>T (Arg2450Ter). At the age of 12 years, MRI identified asymptomatic bilateral optic pathway gliomas (OPGs) affecting both optic nerves and the chiasm. Unusually, over the next decade, imaging showed no signs of progression, and her vision remained unimpaired, with no signs of proptosis or nystagmus. She developed normally through puberty, experiencing menarche at age 14 years, with consistently regular menstrual cycles. However, secondary amenorrhea emerged at the age of 22 after sudden weight gain. At this time MRI of the pituitary gland revealed the existing OPGs and additional exophytic cystic nodules involving the retro-chiasmatic structures, including the hypothalamus. A pelvic ultrasound ruled out polycystic ovaries and showed a thin endometrium. Her hormonal profile indicated hypogonadotropic hypogonadism, with luteinising hormone (LH) at 4.6 IU/l, follicle-stimulating hormone (FSH) at 6.6 IU/l, and oestradiol below 89 pmol/l, with no deficiencies in other pituitary hormones (confirmatory dynamic testing yet to be performed). Endocrine dysfunction due to hypothalamic extension affects 10-20% of individuals with OPGs and NF-1. Notably, the location of the tumours is a stronger predictor of complications than treatment history. Current management guidelines for OPGs depend on whether the tumours affect or threaten vision. OPG glioma occurs in ~15% of patients with NF-1 but is symptomatic 40% of the time. Given these insights, it is important for endocrine teams to recognise the association between OPG, endocrine dysfunction and, more rarely, hypothalamic dysfunction as part of the comprehensive care required for the patient with NF-1.