Hypopituitarism as an Initial Presentation of Silent Squamous Cell Carcinoma of Lung

Background: Symptomatic metastasis to the pituitary gland is a rare, life-threatening condition. A better understanding of its clinical presentation could lead to early diagnosis and also improve quality of life. In this unusual case, we present a patient with hypopituitarism as the first manifestation of undiagnosed squamous cell carcinoma of the lung. Clinical Case: A 56-year-old Caucasian female with past medical history of pre-diabetes, hypertension, hyperlipidemia, and a chronic smoker for 40 years presented with recent onset of headache for two weeks and diplopia for three days. Initial CT head was negative but MRI of brain pituitary scan revealed a large heterogeneously enhancing sellar/suprasellar mass (1.5 x 2.8 x 2.4 cm) extending into the prepontine cistern with probable bilateral cavernous sinus invasion and contacting the optic chiasm without significant compression. Physical examination showed left abducens nerve (CN VI) palsy. Lab results showed elevated prolactin at 67.4 ng/ml (normal postmenopausal: 1.8 – 20.3 ng/ml), normal IGF-1 at 136 ng/ml (normal 48- 235 ng/ml), low TSH at 0.129 µIU/ml (normal 0.3 – 4.5 µIU/ml), low normal Free T4 at 0.50 ng/dl (normal 0.5 – 1.26 ng/dl), low ACTH at 5.1 pg/ml (normal 7.2 – 63.3 pg/ml), low am cortisol at 2.6 mcg/dl (normal 8.7 – 22.4 mcg/dl), low FSH at 2.6 mIU/ml (normal postmenopausal 23.0-116.3 mIU/ml) and low LH at 0.2 mIU/ml (normal postmenopausal 15.9 - 54.0 mIU/ml). She subsequently began treatment for hypopituitarism. Given her smoking history and unusual presentation of cranial nerve palsy, a chest x-ray was ordered and revealed a left upper lobe mass. CT chest confirmed the left upper lobe mass (4.0 x 3.3 x 2.9 cm), and biopsy reported poorly differentiated squamous cell carcinoma. Decompression of the pituitary macroadenoma was performed for symptomatic improvement but was complicated with the development of central diabetes insipidus. Pathology report disclosed metastatic pituitary carcinoma, compatible with primary lung carcinoma. Following surgical resection and radiation therapy to the pituitary gland, the patient remains stable and is currently tolerating all treatment. Conclusion: In a patient with occult malignancy, pituitary metastasis is an exceedingly rare and challenging diagnosis that carries a poor prognosis. The purpose of this abstract is to raise clinical suspicion for sellar metastasis in a patient presenting with hypopituitarism and cranial nerve palsy.