Breast cancer is one of the most common types of cancer, and recurrence within 5 years after diagnosis is frequent; however, rates of recurrence and disease relapse have greatly improved over the past 10 years is not common. In general, the most important sites for metastasis are bone, liver, and lung .
The pituitary gland is a rare site for metastasis for all neoplasm (metastases make up less than 1% of pituitary tumors) [1, 2]. Therefore, the clinical history of our patient shows a rare pattern of breast cancer metastasis. However, cancers of almost all tissues can metastasize to the pituitary gland.
The lung and breast are the most important locations for the primary tumor localizations in men and women, respectively, but in about 5% of cases the primary cancer remains unknown [1, 2, 5–7]. Identification of metastases is more common in elderly patients, and in many cases is suggestive of the presence of disseminated disease and carries a poor prognosis[7, 8]. The hematogenous spread (direct to the pituitary parenchyma or diaphragm sellae through the portal vessels) is the most important mechanism for development of these metastases. Alternative hypotheses for spread are extension from an adjacent bone metastasis or a meningeal spread through the supra-sellar cistern [7, 10]. The posterior lobe is more affected than the anterior lobe, mainly because of the lack of a direct arterial blood supply to the anterior lobe and because there is a larger area of contact between the posterior lobe and the adjacent dura madre[3, 15]. For this reason, the most common sign of this metastatic involvement is diabetes insipidus [1, 2, 4, 13], whereas hypoadrenalism and bilateral hemianopsia, as seen in our patient, are less common [1, 2].
The case shows that the metastatic lesions of pituitary gland can mimic the signs and symptoms of pituitary macroadenoma, leading to a delay in diagnosis of several months. The rarity of this event made diagnosis and the subsequent choice of therapeutic approach difficult.