Review of literature:
Fassett DR, Couldwell WT. Metastases to the pituitary gland. Neurosurg Focus. 2004 Apr 15;16(4):E8.
Reports that previous autopsy series find that pituitary metastases occur in 1-3% of patients with malignant tumors.
Table 1 (p. 2) summarizes sites of primary malignancies from two case series.
Recent case series
Kano H, Niranjan A, Kondziolka D, Flickinger JC, Lunsford LD. Stereotactic radiosurgery for pituitary metastases. Surg Neurol. 2009 Sep;72(3):248-55.
Presents data on 18 patients over 21 years, along with symptoms, primary malignancies, and prognosis.