LAUSR

Introduction Chromosomal abnormalities are a common cause of primary ovarian failure in adolescents. Familial adenomatous polyposis (FAP) is an autosomal dominant predisposition to developing colonic polyposis arising from a germline mutation in the APC gene. Desmoid tumours (DT), otherwise known as ‘deep fibromatosis’, are locally invasive tumours that do not metastasize. DT develop in between 5–30% of FAP carriers and are the second leading cause of death after colorectal carcinoma. Inductions of DT growth in both pregnancy and during oestrogen therapy have been reported. Selective oestrogen receptor modulators, including tamoxifen, are currently being utilised as a therapeutic agent for these tumours. Case description A 14 year old girl was referred due to secondary amenorrhea and raised FSH levels. She entered puberty spontaneously, reached menarche at 13 years of age and had a regular 28 day menstrual cycle. She subsequently became amenorrheic 5 months later. The index case was born at term by spontaneous uncomplicated vaginal delivery with a birth weight of 3.6 kg. Subsequent failure to meet development milestones led to a hearing assessment at 9 months of age which diagnosed bilateral sensorineural hearing loss and bilateral cochlear implants were inserted. Genetics at that stage demonstrated a de novo chromosomal translocation involving the×chromosome and chromosome 15 (46X translocation(X;15)(q13;q13).ishXq13(Xist×2)). Her father was subsequently found to be an FAP carrier and she is confirmed positive for this mutation. She has had annual surveillance colonoscopies; the most recent in June 2018 identified two adenomatous polyps. At 12 years of age she developed desmoid tumours, one located in the submandibular area and the other in the periumbilical area. Investigations confirmed primary ovarian failure with undetectable oestradiol in the presence of elevated gonadotropins, normal androgens and low AMH levels. All other investigations were normal. Discussion Oestrogen therapy is the mainstay of treatment in primary gonadal failure however, exogenous oestrogen is a risk factor in the exacerbation of desmoid tumour growth which could be life limiting. The family and their medical team need to strike a balance enabling optimisation of bone health without increased morbidity from tumour growth. Options were explored with the patient and her family with the ultimate decision to refrain from using exogenous sex hormone therapy with optimization of bone health. This is a complex case that poses therapeutic challenges in management and treatment goals of primary gonadal failure in the setting of desmoid tumours.