Thyroid-stimulating hormone-secreting pituitary neuroendocrine tumor (TSH-PitNet) diagnosed during pregnancy and treated with a somatostatin analog

OBJECTIVE: Thyroid-stimulating hormone (TSH)-secreting pituitary neuroendocrine tumors (TSH-PitNET) are extremely rare during pregnancy, with limited understanding of their impact. CASE REPORT: A primiparous woman in her mid-20s was diagnosed with TSH-PitNET during pregnancy following symptoms, including hyperemesis gravidarum and mild palpitation. At 12 weeks of gestation, a blood test revealed that TSH was not suppressed despite elevated thyroid hormone levels, consistent with SITSH (syndrome of inappropriate TSH secretion). No thyroid hormone receptor β (TRβ) mutation was detected. MRI revealed a pituitary macroadenoma, and TSH-PitNET was diagnosed. Monthly lanreotide injections were administered from 18 weeks until term. At 40 weeks, she underwent an emergency cesarean delivery due to severe headache and mild hypertension, delivering a healthy infant. Transsphenoidal macroadenoma resection was performed three months postpartum. CONCLUSION: This case highlights that a conservative approach with lanreotide and close monitoring can achieve favorable outcomes for both mother and child in TSH-PitNET during pregnancy.