A Rare Case of Sellar Metastastic Renal Cell Carcinoma Mimicking Pituitary Adenoma - a Case Report

Introduction: Metastatic sellar masses are very contributing to 2% of all sellar masses, and up to 0.87% of all metastases to the brain. Breast and lung cancer contribute for up to 60% of all sellar metastases but it is important to recognize other cancers that can also metastasize to pituitary gland. Renal Cell carcinoma (RCC) is number nine on that list. Here we present a case of rare RCC metastasis to pituitary which was mistaken as pituitary adenoma to emphasize early recognition and management of pituitary metastases which may result in better patient’s outcomes and prognosis. Case Presentation: 7 2 year-old male with a remote history of left sided RCC presented with worsening diplopia, blurry vision and headaches for 2 months. Physical exam was remarkable for right sided ptosis with right oculomotor, trochlear and abducens palsy. Computed Tomography Imaging (CT) of the brain showed hyperdense sellar/suprasellar fullness. Magnetic Resonance Imaging (MRI) with and without contrast of the brain showed 2.2 x 1.7 cm enhancing mass in the right cerebellopontine angle with local mass effect concerning for a pituitary tumor. Laboratory work-up was remarkable for hyperprolactinemia 36.5 ng/mL, low TSH <0.015 mU/L, and normal ACTH, FSH and LH levels. Patient underwent endoscopic trans-nasal resection of pituitary tumor. Surgical pathology of the tumor was consistent with metastatic renal cell carcinoma. He was discharged with appropriate multidisciplinary outpatient follow up with endocrinology, oncology and radiology. Discussion: Pituitary metastasis is very rare and often mistaken for pituitary adenoma. Only 7% of Pitutary metastases are symptomatic. Symptom presentation depends on the location of metastases. They include diabetes insipidus (45.2%), visual field defects (27.9%), hypopituitarism (23.6%), ophthalmoplegia (21%), headache (15.8%) and hyperprolactinemia (6.3%). Although, there is no gold standard imaging for sellar masses, both thin-section CT and MRI are beneficial. CT is used for visualizing bony destruction and calcification, on the other hand MRI demarcates lesions in that area. Due to its rarity, there is no standardized guideline therapy for pituitary metastasis and it should be individualized based on patient’s presentation, but it should be multidisciplinary approach of surgical resection, postoperative stereotactic radiosurgery, chemotherapy, and hormone replacement therapy. Prognosis of metastases to pituitary is very poor, with reported six to twenty-two months post resection survival. Factors contributing to prolonged survival are younger age, single/small metastases, and locally guided radiation therapy. Conclusion: This case is to shed light on early recognition of sellar metastasis as a challenging diagnosis especially in patients with rapidly growing pituitary mass and neurological symptoms with history of malignancy for better outcomes.