Pituitary metastasis unveiling a lung adenocarcinoma.

Summary: Pituitary metastasis (PM) can be the initial presentation of an otherwise unknown malignancy. As PM has no clinical or radiological pathognomonic features, diagnosis is challenging. The authors describe the case of a symptomatic PM that revealed a primary lung adenocarcinoma. A 62-year-old woman with multiple sclerosis and no history of malignancy, incidentally presented with a diffusely enlarged and homogeneously enhancing pituitary gland associated with stalk enlargement. Clinical and biochemical evaluation revealed anterior hypopituitarism and diabetes insipidus. Hypophysitis was considered the most likely diagnosis. However, rapid visual deterioration and pituitary growth raised the suspicion of metastatic involvement. A search for systemic malignancy was performed, and CT revealed a lung mass, which proved to be a lung adenocarcinoma. Accordingly, the patient was started on immunotherapy. Resection of the pituitary lesion was performed, and histopathology analysis revealed metastatic lung adenocarcinoma. Following surgery, the patient underwent radiotherapy. More than 2 years after PM detection, the patient shows a clinically relevant response to antineoplastic therapy and no evidence of PM recurrence.

Learning Points: Although rare, metastatic involvement of the pituitary gland has been reported with increasing frequency during the last decades. Pituitary metastasis can be the initial presentation of an otherwise unknown malignancy and should be considered in the differential diagnosis of pituitary lesions, irrespective of a history of malignancy. The sudden onset and rapid progression of visual or endocrine dysfunction from a pituitary lesion should strongly raise the suspicion of metastatic disease. MRI features of pituitary metastasis can overlap with those of other pituitary lesions, including hypophysitis; however, rapid pituitary growth is highly suggestive of metastatic disease. Survival after pituitary metastasis detection has improved over time, encouraging individualized interventions directed to metastasis to improve quality of life and increase survival.