Pituitary Metastasis From Adenoid Cystic Carcinoma Presenting with Panhypopituitarism and Diabetes Insipidus

Objective: Adenoid cystic carcinoma (ACC) is a rare malignancy that most often originates in the salivary glands. While it commonly metastasizes to the lungs, liver, and bone, central nervous system involvement, particularly of the pituitary gland, is exceedingly rare. The objective of this report is to describe a patient with ACC of the submandibular gland presenting with pituitary metastasis manifesting as panhypopituitarism and diabetes insipidus (DI). Case Report: A 64-year-old female presented with intractable vomiting, abdominal pain, and worsening blurry vision. She had a recent diagnosis of metastatic carcinoma. Physical examination was notable for a large left neck mass and left temporal visual field deficit. Magnetic resonance imaging of the pituitary revealed intrasellar mass with suprasellar extension. Hormonal evaluation was significant for panhypopituitarism. The hospital stay was complicated with the development of DI. The patient underwent endoscopic endonasal resection of the pituitary mass, and pathology confirmed metastatic ACC. Discussion: This case highlights a rare instance of pituitary metastasis from submandibular gland ACC, presenting initially with anterior pituitary failure and later with DI. Imaging and hormonal evaluation raised suspicion for metastatic involvement, which was confirmed histologically following surgical resection. Pituitary metastasis of ACC is exceptionally rare, particularly from a submandibular primary. Conclusion: This case confirms the need to consider pituitary metastasis in patients with known malignancy who present with panhypopituitarism and new-onset DI. Early imaging and surgical evaluation can aid in proper diagnosis and management.