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INTRODUCTION Because treatment and clinical management decisions for children with NF1-OPG remain challenging, we sought to establish evidence-based guidelines. We prospectively enrolled children with newly-diagnosed NF1-OPGs, and gathered standardized clinical neuro-oncology and ophthalmology assessments. METHODS Only children with NF1 and newly diagnosed OPGs, confirmed by central review, were eligible. Indications for obtaining the initial MRI, as well as factors associated with the decision to treat with chemotherapy or observe without treatment, were obtained. Quantitative visual acuity (VA), other ophthalmic features, and imaging were captured at standard time points. Goal enrollment is 250 subjects. RESULTS One-hundred thirty-three children (52% female) from 20 institutions met inclusion criteria, and were included in this preliminary analysis. Eighty-six percent of subjects were able to perform quantitative VA testing at enrollment. The most common reasons for the diagnostic MRI included screening related to NF1 diagnosis (36.8%), ophthalmologic concerns (29.3%), and non-ophthalmologic concerns (24.8%), such as headache. To date, twenty subjects have initiated treatment with chemotherapy, twelve (9%) at the time of the initial OPG diagnosis. Median age at OPG diagnosis was 3.1 years. Age and sex distribution were similar in subjects immediately entering the observation and treatment arms (median age 3.0 versus 3.5 years, respectively). CONCLUSION Most children with NF1-OPGs are observed at time of their initial OPG diagnosis, rather than treated. Importantly, a large proportion of children are able to complete quantitative VA testing at enrollment. Once enrollment is complete, these data will help to establish evidence-based guidelines for clinical management of NF1-OPGs.

BACKGROUND: Prolactin-secreting macroadenomas are generally not life-threatening and often present with visual impairment. Medical management with a dopamine agonist is typically the treatment of choice, which significantly reduces the tumor size and improves symptoms without surgical morbidity. In this report, we present a case of an acidophilic stem cell adenoma (ASCA) that was slowly responsive to medical management, but exhibited marked visual recovery after surgical resection. RESULTS: A 15 year-old previously healthy male presented with significantly decreased peripheral vision but no other neurologic or endocrinologic symptoms. Initial magnetic resonance imaging of the brain/spine revealed a mass in the suprasellar and sellar regions with extension into the cavernous sinus and a prolactin level of 644, leading to a presumptive diagnosis of macroprolactinoma. Medical management with cabergoline resulted in some decrease of the prolactin level, but no radiographic improvement or visual recovery after two months. He subsequently underwent endoscopic endonasal transsphenoidal resection with near-total restoration of his peripheral vision post-operatively and significant improvement of his prolactin level. Pathology was consistent with an ASCA (staining positively with prolactin, growth hormone (a-subunit), and pituitary-specific positive transcription factor 1), a rare pituitary adenoma that tends to be invasive and often requires more aggressive therapy; the patient thus underwent focal consolidative proton beam irradiation. CONCLUSION: This case highlights the importance of considering acidophilic stem cell adenomas in the differential of medically-resistant pituitary macroadenomas and early consideration of resection in cases where significant visual or other symptoms exist, as timely intervention may substantially improve functional outcomes.

Optic pathway gliomas (OPGs) are glial tumors that arise early during development in 15-20% of patients with Neurofibromatosis Type I (NF1). While chemotherapy is often used for patients who have growing tumors and/or vision loss associated with the tumor, a minority of patients have improvement in their vision following treatment. Thus, a new approach to treatment is needed to improve the visual outcomes in this patient population. In our laboratory, we have a Nf1-deficient conditional knockout mouse model that develops optic pathway gliomas around 60 days of age (P60). These mice have associated axon degeneration, loss of retinal ganglion cells, and evidence of vision loss on behavioral testing, thus making this a good model to use in order to identify the optimal therapeutic time window that improves or prevents vision loss. In this study, we treated NF1-deficient mice with a Mek-inhibitor during different developmental time windows and measured response to treatment in terms of nerve cellularity, axon integrity, and retinal ganglion cell loss. We found that response to treatment is highly dependent on when the therapy is initiated during OPG development, and the best response occurred when therapy was initiated early during this process. This study suggests that the timing of therapy initiation is critical for optimal outcomes in NF1-associated OPGs.