Mammosomatotroph pituitary neuroendocrine tumour in a 7-year-old boy: case report

Pituitary neuroendocrine tumours (PitNETs) of the mammosomatotroph type are exceedingly rare in childhood, particularly in children under 10 years old. Existing high-quality, evidence-based data primarily derive from large adult cohorts, while paediatric evidence remains extremely limited. Case presentation A 7-year-old boy presented with headaches, transient amaurosis, and accelerated linear growth (+3.0 SDS), clinically consistent with pituitary gigantism. MRI revealed a 1.9 × 1.7 × 2.8 cm predominantly cystic sellar-suprasellar mass compressing the optic chiasm, radiologically indistinguishable from craniopharyngioma. Preoperative biochemistry showed GH > 40 ng/mL, IGF-1 = 479 ng/mL (reference range: 40-255 ng/mL), and PRL = 129 ng/mL (reference range: 2.1-17.7 ng/mL). Transcranial gross-total resection normalized GH (5.15 ng/mL), PRL (9.56 ng/mL), and IGF-1 (257 ng/mL) without adjuvant medical therapy. Histology confirmed a paediatric case of mammosomatotroph PitNETs. Targeted next-generation sequencing detected a pathogenic SMARCB1 deletion but no AIP, GNAS, or USP8 variants. The patient remains clinically and biochemically well 8 months postoperatively.

This 7-year-old boy represents one of the youngest recorded cases of a mammosomatotroph pituitary neuroendocrine tumour. The atypical presentation, dominated by mass-effect symptoms and pituitary gigantism, highlights the necessity of early hormonal and genetic screening when evaluating complex paediatric sellar masses.