Metastases to the Pituitary Gland

Daniel R. Fassett, M.D.; William T. Couldwell, M.D., PhD

Disclosures

May 18, 2004

Findings

Based on findings in early autopsy series, it appears that the majority of pituitary metastases are clinically silent. In the autopsy study conducted by Teears and Silverman[25] only 7% of pituitary metastases were symptomatic. Among the more commonly reported symptoms are DI, ophthalmoplegia, headache/pain, visual field defects, and anterior pituitary dysfunction ( Table 3 ).

Authors of many studies have reported especially high rates of DI in their series of patients; this condition was thought to be caused by an increased prevalence of posterior pituitary involvement.[25] Morita, et al.,[22] have noted that DI is more common in patients with symptomatic pituitary metastases than in those with symptomatic adenomas. Approximately 60% of the patients treated by these authors for pituitary metastases had DI, whereas only 1% of their patients with adenoma presented with this condition. Other authors have reported that between 14 and 20% of patients presenting with DI will have pituitary metastases.[9,12]

Because of the invasiveness of tumors that metastasize to the pituitary, they are also likely to produce visual deficits from suprasellar extension and painful ophthalmoplegia from invasion of the cavernous sinus.[11,22,23] Many authors emphasize that anterior pituitary hormonal dysfunction is probably underreported in patients with this disease because a significant percentage of patients are likely to decline as a result of their systemic disease, thus masking the symptoms of anterior pituitary dysfunction.

In some patients, symptoms related to pituitary metastases may be the first manifestation of a malignant neoplasm. Morita and colleagues[22] and Branch and Laws[3] have noted that, in a significant percentage (56 and 64%, respectively) of patients exhibiting symptoms, the pituitary symptoms were the initial presentation of malignant disease.

Sensitive and specific criteria for differentiating pituitary metastases from pituitary adenomas have not been reported. Many authors place more emphasis on clinical history than on neuroimaging findings. In older patients, patients with a history of a malignant neoplasm, and patients with symptoms such as DI and ophthalmoplegia, metastasis should be strongly considered for a pituitary mass (Fig. 1). A few imaging characteristics have been reported to be helpful in differentiating pituitary metastases from pituitary adenomas; these include the following: 1) thickening of the pituitary stalk;[20,22] 2) loss of a high-intensity signal from the posterior pituitary;[4] 3) isointensity on both T1- and T2-weighted MR images;[20] 4) invasion of the cavernous sinus;20 and 5) sclerotic changes around the sella turcica.[13] Although these findings may indicate the possibility of metastases, they are in no way specific for pituitary metastases.

Gadolinium-enhanced T1-weighted MR images obtained in a 75-year-old man with a history of renal cell carcinoma who presented with diplopia, due to sixth cranial nerve palsy, and a pituitary mass. Left: Axial image revealing a 1.5-cm-wide intrasellar mass. Right: Sagittal image demonstrating a pituitary mass with thickening of the pituitary stalk.

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