2025 Proffered Presentations
S343: INDICATIONS AND TECHNIQUES FOR POSTERIOR PITUITARY BIOPSY
Kyly Hiatt, BS; Thomas Hanks, BS; Spencer Raub, BA; Jessica Eaton; Kaity Hartl, MS, PAC; Dominic Nistal, MD; Fatima El-Ghazali, MD; Aria Jamshidi, MD; Manuel Ferreira, MD, PhD; Jacob Ruzevick, MD; Samuel Emerson, MD, PhD; University of Washington
Background: Histology is critical to the identification of lesions in the hypothalamus and pituitary stalk. Biopsy of these structures, however, is associated with an increased risk of endocrine dysfunction. It has been hypothesized that due to the structural continuity of the neurohypophysis, posterior lobe tissue may reflect pathology located outside the posterior lobe itself, often located in the pituitary stalk. The posterior pituitary lobes are a direct structural extension of the hypothalamus, comprising axons from the supraoptic and paraventricular nuclei. Comparatively, the anterior pituitary lobe has no direct structural connection to the hypothalamus and functions through a capillary portal system. Given this anatomic continuity, the posterior lobe offers the capacity to indirectly sample pathology of the hypothalamus and pituitary stalk. In support of this hypothesis, we present a case series of three patients who underwent posterior lobe biopsy for hypothalamic and/or stalk pathologies, demonstrating successful histologic diagnosis of lesions in the hypothalamic infundibulum without acute worsening of pituitary function.
Observations: We present three illustrative cases of posterior lobe biopsy effectively demonstrating the histology of tumors within the hypothalamus/infudibulum. Biopsies were performed via endoscopic endonasal transsphenoidal surgery (ETSS). A 56-year-old woman with nausea and persistent polydipsia had a lesion along the infundibulum. Posterior lobe biopsy confirmed a diagnosis of a metastasis of primary breast cancer. A 62-year-old woman and 65-year-old woman both presented with panhypopituitarism and lesions within the pituitary stalk. Transsphenoidal posterior lobe sampling identified pituicytoma and non-Langerhans cell histiocytosis, respectively. Postoperatively, none of these patients experienced acute worsening of hypothalamic or pituitary function.
Discussion: Sampling of the posterior pituitary gland may act as a surrogate for direct hypothalamic or infundibular biopsy. This allows histologic analysis of these structures without the high risks of direct biopsy. This case series overviewed a standard direct approach to the posteroinferior region of the sella with visualization of the posterior pituitary gland. In addition to the improved safety of this procedure, it may also aid in the diagnosis of pathologies such as lymphoma and sarcoidosis. Definitive diagnosis was not impacted in our patient with histiocytosis despite a prolonged course of steroids. This should be considered in similar patients, however, as it may decrease diagnostic yield.
Conclusion: Initial reports suggest posterior lobe sampling is associated with lower rates of endocrine dysfunction compared to traditional stalk biopsy. Additional cases implementing this procedure are needed to robustly substantiate this hypothesis.