Recurrent Head and Neck Adenocarcinoma Presenting With a Pituitary Mass

Abstract

\n Background: Metastasis to the pituitary gland is a rare condition. Only 1.8% of all surgically resected pituitary masses are metastases with the majority originating in the breast and lung (1). Salivary gland tumors rarely metastasize to the brain and only a few cases have been reported in the literature. Clinical Case: A 61 year-old woman presented to an outside emergency department with horizontal diplopia, blurry vision and left-sided sharp frontal headaches. MRI of the head showed a large, 2.0 x 4.6 x 1.8 cm sellar/suprasellar mass involving both cavernous sinuses, encasing the right internal carotid artery which was narrowed, and compressing the optic chiasm. Her past medical history was significant for adenocarcinoma of the left buccal mucosa and masseteric space, treated with resection in 2016, and a second resection in 2018 for recurrence followed by radiation therapy. Areas were identified where focal perineural invasion was present. She was referred to our institution for treatment recommendations for the sellar/suprasellar lesion. Laboratory testing revealed secondary hypothyroidism, adrenal insufficiency and partial diabetes insipidus, and she was started on replacement hormone therapy with levothyroxine and hydrocortisone. Neurosurgery and ENT evaluated patient and a surgical biopsy and subtotal resection via an endoscopic endonasal transsphenoidal approach was recommended for diagnosis and possible decompression of the optic chiasm. The final pathology was consistent with metastatic, high grade adenocarcinoma, supported by positive mucicarmine stain for mucin, positive immunohistochemical stain for CAM 5.2 and CK7 and negative immunohistochemical stains for the pituitary transcription factors, PIT-1 and SF-1. Conclusion: We report the second case in the literature of adenocarcinoma of the head and neck to the pituitary gland. In our case, radiological appearance of the tumor together with patient’s malignancy history led to the consideration of a pituitary metastasis. Tumors invading the cavernous sinus and causing internal carotid artery compression are rarely pituitary adenomas (2). Presence of these imaging features in patients with known risk factors for malignancy should raise suspicion for pituitary metastasis. The route of spread from the masseteric space to the sellar region remains unclear. Tumor metastasis can occur through direct invasion, hematogenous spread and perineural spread. Hematogenous spread and/or perineural spread along the trigeminal nerve are the most likely routes of metastasis in this case.\n Reference: (1)Javanbakht A, D’Apuzzo M, Badie B, Salehian B. Pituitary metastasis: A rare condition. Endocr Connect 2018; 7(10):1049-1057. PMID: 30139817.\n (2)Molitch ME et al (2012) Tumors invading the cavernous sinus that cause internal carotid artery compression are rarely pituitary adenomas. Pituitary 15(4):598–600