Endocrine Abstracts

JOINT1560

Pituitary neuroendocrine tumors (PitNETs) located solely in the pituitary stalk, without affecting the pituitary gland, are exceptionally uncommon. To date, only a limited number of cases has been documented in the literature. Herein, we report a case of a post-surgical PitNET residue confined solely to the pituitary stalk, observed during a morphological follow-up two years after endoscopic transsphenoidal surgery. We describe the case of a 23-year-old woman who initially presented with secondary amenorrhea and galactorrhea, leading to a diagnosis of prolactin-secreting PitNET. Owing to the failure of medical therapy with cabergoline, the patient underwent endoscopic transsphenoidal surgery. Postoperatively, her prolactin levels decreased to 30 ng/ml (n<26,5), with no evidence of pituitary dysfunction. However, one year after surgery, hyperprolactinemia recurred, accompanied by secondary amenorrhea and galactorrhea, prompting the reinitiation of cabergoline therapy to suppress prolactin secretion. Two years after the surgical intervention, routine morphological surveillance revealed a thickening of the pituitary stalk. Magnetic resonance imaging (MRI) demonstrated a 4-mm thick mass of homogeneous signal intensity on both T1-weighted and T2-weighted imaging, localized within the pituitary stalk. The patient remains free of diabetes insipidus. Comprehensive evaluation excluded alternative etiologies of pituitary stalk thickening, including lymphoma, craniopharyngioma, germ cell tumors, and granular cell tumors. The patient declined endoscopic transsphenoidal biopsy. Consequently, an annual MRI-based follow-up is recommended. During the surveillance period from 2010 to 2024, the pituitary stalk thickening remained stable. Following a multidisciplinary team review including an expert neuroradiologist, a definitive diagnosis of PitNET residue confined within the pituitary stalk was established. The patient’s prolactin level remained stable at 60 ng/ml under a weekly dose of 0.75 mg of cabergoline. Although PitNET residues confined to the pituitary stalk are rare, awareness of their existence is essential for accurate postsurgical assessment. Recognizing this condition can guide appropriate management, prevent unnecessary surgical biopsies, and ensure optimal long-term follow-up.