Small Cell Lung Cancer with Pituitary Metastasis Presenting as Secondary Adrenal Insufficiency: A Case Report and Literature Review.

BACKGROUND Pituitary gland metastasis is rarely the initial presentation of metastatic cancer. Most cases of pituitary gland metastasis are asymptomatic with diabetes insipidus being the most common symptomatic presentation. It can rarely present with symptoms of hormone underproduction such as secondary adrenal insufficiency. Although pituitary gland metastasis is rare, it is underestimated, as it is commonly misdiagnosed with pituitary gland adenoma due to the lack of clear radiological criteria differentiating between both. CASE REPORT We present a case of a 62-year-old male who presented with weakness, blurry vision, and persistent hypoglycemia despite intravenous dextrose infusion and having discontinued taking his diabetes medications. Chest x-ray showed a left hilar mass, while computed tomography scan demonstrated a left superior hilar mass and hilar lymphadenopathy with bilateral adrenal nodules and a T6 vertebral lesion suspicious for metastasis. Further workup showed secondary adrenal insufficiency with a low adrenocorticotropic hormone (ACTH) level. Vertebral biopsy was performed and confirmed the diagnosis of small cell carcinoma of the lung. This was followed by a brain magnetic resonance imaging (MRI), which showed multiple metastatic lesions with an enhancing mass involving the right clivus, sella, and suprasellar cistern with mass effect on the optic chiasm and involvement of the cavernous sinus supporting the diagnosis of pituitary gland metastasis of small cell lung cancer. The patient received brain radiation, and repeated MRI showed regression of the previous MRI findings. CONCLUSIONS Secondary adrenal insufficiency is an unusual presentation of pituitary gland metastasis. Physicians should take into consideration both radiological findings and presentation to differentiate between pituitary gland metastasis and pituitary adenoma.