Doctors Tame a Teenager’s Aggressive Pituitary Tumor With Layered Therapy

A 13-year-old girl whose headaches, rapid growth and 10-kilogram weight gain turned out to be signs of a rare, invasive growth hormone-secreting pituitary tumor has become the subject of a detailed case report describing how doctors eventually brought her disease under control after years of escalating treatment.

The girl was referred to a pediatric neurology department in February 2023 for progressively worsening headaches that had begun the previous June as twice-weekly occipital and temporal pain and had become daily by September, accompanied by retro-orbital pain and only partial response to analgesics. She also reported excessive daytime sleepiness, primary amenorrhea and the striking weight gain. Between September and December 2022 her height had climbed from 175 centimeters to 180 centimeters, and her shoe size had increased by two sizes over the preceding year. On examination at the Children’s Memorial Health Institute in Warsaw, her height was 179.7 centimeters, above the 97th percentile at +3.03 standard deviations, her weight was 74.6 kilograms, and her body mass index was 23 kilograms per square meter at the 87th percentile. Acanthosis nigricans was present in her axillary and inguinal regions.

Routine laboratory tests revealed hyperuricemia with a uric acid of 7.7 milligrams per deciliter, impaired fasting glucose at 103 milligrams per deciliter, marked hyperinsulinemia at 109.1 micro-international units per milliliter and hypertriglyceridemia at 242 milligrams per deciliter. Hormonal evaluation then showed markedly elevated growth hormone at 86.75 nanograms per milliliter, against a reference range below 3.33, and insulin-like growth factor 1 at 977.7 nanograms per milliliter, far above the age-adjusted reference interval of 115.9 to 533.4. During an oral glucose suppression test, her growth hormone nadir was 78.69 nanograms per milliliter, an abnormal failure of suppression. The workup also showed hypogonadotropic hypogonadism and hypoprolactinemia, while her thyroid and adrenal axes were preserved. Magnetic resonance imaging on 20 February 2023 revealed a 38 by 23 by 32 millimeter sellar and suprasellar mass that extended into the interpeduncular and prepontine cisterns, involved the anterior pituitary, pituitary stalk, part of the hypothalamus and the cavernous segments of the internal carotid arteries, and displaced the optic chiasm superiorly.

After neurosurgical consultation, the patient was qualified for tumor resection with preoperative preparation using a somatostatin receptor ligand. Octreotide LAR was started at 30 milligrams every 28 days and was well tolerated, although headaches persisted in less severe form and progressive enlargement of the hands and feet continued. By May 2023, after three doses, growth hormone remained elevated at 107.7 nanograms per milliliter and IGF-1 at 918.5 nanograms per milliliter. The octreotide dose was raised to 40 milligrams and cabergoline was added at 3.5 milligrams per week, but subsequent evaluations over the following months showed no improvement in disease control. The authors note that current evidence does not support routine preoperative medical therapy to improve postoperative remission rates, although selected patients with invasive adenomas may benefit, and in pediatric patients such therapy may be considered to reduce growth velocity and limit further height gain.

In August 2023, approximately six months after diagnosis, the patient underwent an uncomplicated partial resection of the tumor via a right frontal craniotomy rather than the transsphenoidal approach more commonly used in acromegaly, because giant tumors with substantial extrasellar growth may require a transcranial procedure. Histopathological examination confirmed a somatotroph pituitary neuroendocrine tumor with a Ki-67 proliferation index above 5 percent, and electron microscopy showed ultrastructural features of a sparsely granulated subtype. The tumor was classified as grade 2B under the Trouillas classification. After surgery, IGF-1 remained persistently elevated at 1086.5 nanograms per milliliter and growth hormone at 19.2 nanograms per milliliter, although growth hormone had decreased markedly. Octreotide LAR at 40 milligrams every 28 days was reintroduced, and levothyroxine and estradiol replacement were started for confirmed thyrotropic and gonadotropic axis deficiencies. Follow-up MRI three months after surgery showed a marked reduction in tumor volume, but the neurosurgical team concluded that radical treatment was not feasible.

Because of the inadequate response to first-generation somatostatin receptor ligand therapy, pasireotide LAR was initiated in December 2023 at 40 milligrams every 28 days and escalated to 60 milligrams after three months. The drug proved ineffective in achieving disease control and was discontinued after five months of treatment. The authors emphasize that pasireotide LAR is typically used as second-line therapy in adults with acromegaly inadequately controlled despite maximum tolerated doses of first-generation somatostatin receptor ligands, and that data in children and adolescents remain limited. In this patient, neither normalization of IGF-1 concentrations nor control of linear growth was achieved, although follow-up MRI showed stable residual tumor tissue, the drug was well tolerated, and it did not produce any clinically significant deterioration of glucose metabolism, an observation the authors note is consistent with previous reports that younger patients tend to have more favorable glycemic responses to pasireotide LAR.

In May 2024, pegvisomant, a recombinant growth hormone analogue that blocks growth hormone receptors and reduces IGF-1 production, was started at 10 milligrams per day and gradually escalated. The initial response remained unsatisfactory, with persistently elevated IGF-1. After six months of therapy, in October 2024, follow-up pituitary MRI demonstrated slight enlargement of the residual tumor mass and greater compression and remodeling of the left optic tract compared with the previous examination. The authors caution that although tumor enlargement during pegvisomant therapy likely reflects the natural history of the adenoma rather than reduced IGF-1-mediated feedback, careful radiological monitoring is warranted given the drug’s lack of direct pituitary action. Octreotide LAR at 30 milligrams every 28 days was therefore added to the regimen, and during the first months of combined therapy stabilization of the patient’s linear growth was achieved.

Between February and April 2025 the patient underwent fractionated proton beam radiotherapy, with the clinical target volume encompassing the residual tumor and both cavernous sinuses receiving a total dose of 50.4 Gy in 1.8 Gy fractions, followed by a boost to the residual tumor to a cumulative dose of 54 Gy. The first normalization of IGF-1 was achieved in October 2025, after 18 months of pegvisomant therapy, when the patient was receiving 30 milligrams per day of pegvisomant combined with octreotide LAR at 40 milligrams every 28 days. The authors point out that biochemical response came approximately six months after completion of radiotherapy, so the delayed therapeutic effect of radiotherapy may have contributed substantially to the normalization, suggesting that the cumulative effects of sequentially administered modalities ultimately achieved biochemical control. Follow-up MRI in October 2025 showed a slight reduction in the residual tumor, and the latest scan in May 2026 showed a stable remnant.

The treatment came at a lasting endocrine cost. The function of the remaining pituitary axes did not recover during follow-up, and the patient continues to require levothyroxine at 150 micrograms daily and sex hormone replacement with oral estradiol and micronized progesterone. In April 2026, approximately one year after completing proton beam radiotherapy, she developed secondary adrenal insufficiency requiring hydrocortisone and prasterone replacement. Genetic testing using next-generation sequencing was performed on both the patient and her twin sister and revealed no germline pathogenic variants in a panel of pituitary tumor predisposition genes including AIP, MEN1, PRKAR1A, CDKN1B and others, despite the fact that a genetic cause is identified in nearly half of patients with pituitary gigantism and testing is recommended for all pediatric patients with growth hormone excess.

The authors conclude that the case illustrates the complexity of treating aggressive growth hormone-secreting pituitary neuroendocrine tumors in adolescents and reinforces the value of individualized, multidisciplinary management with prolonged follow-up. Pediatric-onset cases account for less than 5 percent of all acromegaly patients, and affected children more often present with large, invasive tumors, high hormone concentrations and resistance to medical therapy. Combination therapy with pegvisomant and somatostatin receptor ligands has been successfully reported in pediatric patients with growth hormone excess and is particularly recommended for those needing additional treatment to achieve biochemical control, especially with large tumors or persistent headaches. As a single-patient case report, the findings cannot establish treatment efficacy broadly, but they document that in one refractory adolescent, combination therapy with pegvisomant and octreotide LAR provided sustained biochemical control when surgery, radiotherapy and standard medical therapy had not, and that regular pituitary MRI is warranted during pegvisomant treatment because tumor enlargement may occur.

Subject of Research: Multimodal treatment of adolescent acrogigantism caused by an aggressive growth hormone-secreting pituitary tumor

Article Title: Case Report: Neurosurgery, octreotide, cabergoline, radiotherapy, pasireotide and pegvisomant – a multimodal strategy for adolescent acrogigantism

Article References: Dzialach, L., Bogusz-Wójcik, A., Moszczyńska, E., Wojciechowska-Luzniak, A., Zieliński, G., Maksymowicz, M., & Witek, P. (2026). Case Report: Neurosurgery, octreotide, cabergoline, radiotherapy, pasireotide and pegvisomant – a multimodal strategy for adolescent acrogigantism. Frontiers in Endocrinology, 17, Article 1954698. https://doi.org/10.3389/fendo.2026.1954698

Image Credits: AI Generated

DOI: 10.3389/fendo.2026.1954698

Keywords: acrogigantism, acromegaly, pituitary neuroendocrine tumor, growth hormone, IGF-1, pegvisomant, octreotide LAR, pasireotide, proton beam radiotherapy, pediatric endocrinology, case report, hypopituitarism