Southwestern Internal Medical Conference: New developments in the diagnosis and treatment of sexual precocity

Precocious and accelerated puberty in children with neurofibromatosis type 1: results from a close follow-up of a cohort of 45 patients

PURPOSE

Central precocious puberty (CPP) in neurofibromatosis type 1 (NF1) occurs mainly in association with optic pathway glioma (OPG), but it can also develop in the absence of OPG. The aim of this study was to analyze the prevalence of puberty disorders in children with NF1 and its association with OPG and its location.

METHODS

A retrospective study of 45 children with NF1 (68.9% boys) followed at our center between 2008 and 2020 was conducted. A cerebral MRI scan was performed in all children. We analyzed auxological, laboratory, and imaging data of children with CPP or accelerated puberty (AP). Treatments used for CPP/AP and their effect on height were also evaluated.

RESULTS

The prevalence of puberty disorders in our cohort was 17.8% (male to female ratio of 7:1). CPP and AP were diagnosed in 8/45 (17.8%) NF1 children. Among children with puberty disorders, 5/8 (62.5%) had an OPG with chiasm involvement, 1/8 (12.5%) had an isolated optic nerve tumor, and 2/8 (25%) did not have any evidence of OPG on MRI. Fisher's exact test showed an association between CPP/AP and chiasm OPG (p = 0.025). Treatment with triptorrelin was initiated in 5/8 children, of whom four attained final predicted height.

CONCLUSION

Our study confirms the higher prevalence of CPP/AP in NF1 patients, as well as an association between chiasm OPG and puberty disorders. However, CPP/AP also occurred in the absence of OPG with an incidence of 9.1%. Comprehensive evaluation of every child with NF1 regardless of the presence of OPG is therefore essential.

Optic pathway glioma and endocrine disorders in patients with and without NF1

BACKGROUND

Optic pathway gliomas (OPGs) are classified by anatomic location and the association with neurofibromatosis type 1 (NF1). Children with OPGs face sequelae related to tumor location and treatment modalities. We assessed the prevalence of endocrine dysfunction in children with OPGs and compared outcomes between those with and without NF1.

METHODS

We performed a retrospective medical record review of medical history, and clinical and laboratory data, of children diagnosed with OPGs (n = 59, 61% with NF1) during 1990-2020, followed at a tertiary endocrine clinic. Growth and puberty parameters and occurrence of endocrine dysfunction were evaluated.

RESULTS

Isolated optic nerve involvement was higher among patients with than without NF1. Patients without NF1 were younger at OPG diagnosis and more often treated with debulking surgery or chemotherapy. At the last endocrine evaluation, patients without NF1 had comparable height SDS, higher BMI SDS, and a higher rate of endocrine complications (78.3% vs. 41.7%, p = 0.006). Younger age at diagnosis, older age at last evaluation, and certain OPG locations were associated with increased endocrine disorder incidence.

CONCLUSIONS

Endocrine dysfunction was more common in patients without NF1; this may be related to younger age at presentation, tumor locations, a greater progressive rate, and more aggressive treatments.

IMPACT

The literature is sparse regarding sporadic OPGs, and the mean duration of follow-up is shorter than at our study. Our data show a higher rate of endocrine dysfunction in patients with OPGs than previously described. We also found a higher prevalence of endocrine dysfunctions among patients without compared to those with NF-1. A better understanding of the true prevalence of endocrine disabilities that may evolve along time can help in guiding physicians in the surveillance needed in patients with OPG.

Precocious puberty in children with neurofibromatosis type 1

We undertook a comprehensive study of children with neurofibromatosis type 1 (NF-1) cared for in a large multidisciplinary clinic to determine the prevalence of precocious puberty and its relationship to optic pathway tumors (OPTs). Precocious puberty was diagnosed in 7 of 219 children with NF-1 (5 boys and 2 girls) examined between Jan. 1, 1985, and April 20, 1993. All seven children had OPTs involving the optic chiasm; they represented 39% of children with NF-1 and chiasmal tumors (95% confidence interval, 17% to 64%). Eleven prepubertal children (aged 2 to 10 years) with NF-1 and OPTs, and age- and sex-matched NF-1 control subjects without OPTs, underwent luteinizing hormone-releasing hormone (LH-RH) stimulation tests. Two boys with OPTs had pubertal luteinizing hormone (LH) responses, and testosterone levels > 10 ng/dl. Basal LH levels were also elevated in these two boys when tested with a very sensitive immunochemiluminometric assay. None of the children without an OPT had either a pubertal response to LH-RH or an elevated basal LH level. We conclude that precocious puberty in children with NF-1 is found exclusively in those who have OPTs involving the optic chiasm; it is a common complication in those children. With the use of a highly sensitive LH assay, biochemical evidence of hypothalamic-pituitary-gonadal axis activation may be demonstrated, even without provocative testing.

Leuprorelin. A review of its pharmacology and therapeutic use in prostatic cancer, endometriosis and other sex hormone-related disorders

Leuprorelin (leuprolide acetate) is a gonadotrophin-releasing hormone (GnRH) analogue used to treat a wide range of sex hormone-related disorders including advanced prostatic cancer, endometriosis and precocious puberty. It acts primarily on the anterior pituitary, inducing a transient early rise in gonadotrophin release. With continued use, leuprorelin causes pituitary desensitisation and/or down-regulation, leading to suppressed circulating levels of gonadotrophins and sex hormones. Clinical trials in men with advanced prostatic cancer demonstrate that leuprorelin (usually monthly depot injections of 3.75 or 7.5 mg) is less likely to cause serious adverse cardiovascular effects than diethylstilbestrol, and has comparable efficacy to bilateral orchiectomy or other GnRH analogues. Therefore, the choice between leuprorelin and orchiectomy may be made on the basis of the patient's treatment preference, along with specific patient characteristics and cost implications. Monthly intramuscular or subcutaneous administration of depot leuprorelin 3.75 mg was superior to placebo, and comparable to oral danazol 800 mg/day or intranasal buserelin 900 micrograms/day, in achieving objective and subjective responses in women with endometriosis. Thus, leuprorelin is an effective alternative to other treatments for women with endometriosis, but the recommended duration of its use in this clinical setting is limited to 6 months because it reduces bone mineral density. In children with central precocious puberty, leuprorelin (usually monthly intramuscular or subcutaneous injections of depot leuprorelin 3.75 to 15mg) decreases mean growth velocity and signs of sexual maturation and increases predicted adult height compared with baseline measurements. Although effects on final adult height are predicted from available data and require confirmation in long term follow-up studies, the absence of effective alternatives to GnRH analogues makes leuprorelin a first-line therapy for children with this rare disease. In women with uterine leiomyomata, monthly intramuscular administration of depot leuprorelin 3.75 mg for 6 months markedly reduces uterine volume and fibroid-related symptoms, but, as with other GnRH analogues, these effects dissipate following discontinuation of the drug. As adjuvant therapy in women undergoing in vitro fertilisation or gamete intrafallopian transfer, leuprorelin (usually 0.5 to 1 mg/day subcutaneously) reduces the risk of cancelled cycles for oocyte retrieval by preventing premature luteinisation. While some studies demonstrate an improvement in intermediate end-points such as increased number of mature oocytes retrieved and embryos available for transfer, a significant effect has not been demonstrated on the rate of live births per stimulated cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Histrelin. A review of its pharmacological properties and therapeutic role in central precocious puberty

Histrelin is a synthetic gonadotrophin-releasing hormone (GnRH) agonist which, when administered over a prolonged period, suppresses the release of gonadotrophins from the anterior pituitary. Data from clinical trials undertaken in small numbers of patients with idiopathic central precocious puberty have demonstrated that histrelin 8 to 10 micrograms/kg/day administered subcutaneously desensitises the anterior pituitary to gonadotrophin secretion within 3 months, ablating the pubertal gonadotrophin response to GnRH stimulation and reducing circulating gonadal sex steroid levels. When histrelin is administered to treat central precocious puberty, the rate of secondary sexual maturation is slowed and in some cases there is a reversal of maturation which occurs before initiation of treatment. Of equal importance, histrelin therapy appears to have decelerating effects on skeletal maturation, allowing more statural growth; an increase in final adult height is predicted from available data, but will need to be confirmed in long term follow-up studies currently being undertaken. The most common adverse event reported during histrelin therapy was a skin reaction at the site of subcutaneous injection. Few patients have discontinued therapy because of any adverse event. Although experience with histrelin is limited, the absence of effective clinically available alternatives and the demonstrated efficacy of histrelin justifies its place as a first-line therapy for patients with central precocious puberty.