Tumor-to-tumor metastasis: lung adenocarcinoma into a clinically non-functioning gonadotroph pituitary adenoma: A rare case

We report a rare case of a metastatic lung adenocarcinoma to a clinically non-functioning pituitary gonadotroph adenoma in a 66-year-old male experiencing progressive headaches and diminished vision. Magnetic resonance imaging revealed a large tumor containing cystic cavity and acute hemorrhagic areas in the sella turcica and extending into the suprasellar cistern. Pathologic examination was consistent with a metastasizing lung adenocarcinoma to a clinically non-functioning pituitary adenoma. Immunohistochemistry revealed both pituitary adenoma and metastatic adenocarcinoma containing FSH and LH immunoreactive cells in the pituitary adenoma whereas napsin A, TTF-1, cytokeratin7, Pancytokeratin and galectin-3 immunopositivity were evidenced by adenocarcinoma cells within sinusoids and around blood vessels. The patient underwent a transthoracic fine needle biopsy that was positive for adenocarcinoma (Napsin-A positive, p63 negative). It was therefore concluded that the primary site for the sellar metastasis was in the lung. Primary metastasis to pituitary gland is rare with the most common primary sites include lung, breast, kidney and the gastrointestinal tract. Although rare, any case with progressive local pressure symptoms and endocrinologic stigmata with or without other signs of malignancy requires further examination to rule out pituitary metastasis