Metastatic adenocarcinoma to a pituitary adenoma

Metastatic tumor to a pituitary adenoma has rarely been documented in the literature. We report a case of a 60-year-old man who presented with a history of progressive blurred vision and an incomplete homonymous hemianopsia. Magnetic resonance imaging showed a 5 cm heterogeneous mass which focally was contrast enhancing, involving the sella turcica and extending into the right cavernous sinus region. After worsening symptoms, repeat magnetic resonance imaging showed an increase in size of the lesion. Histologically, the mass consisted of a metastatic adenocarcinoma to a nonsecreting pituitary adenoma. The carcinoma stained focally positive with antibodies to carcinoembryonic antigen, cytokeratin 20, and p53 (60% of tumor cells), and did not stain with antibody to cytokeratin 7. The histologic appearance and immunohistochemical profile of the metastasis suggests a colorectal primary.