pituitary carcinoma

Pituitary carcinomas are rare tumors indistinguishable from pituitary adenomas on imaging and defined only by the presence of central nervous system or systemic metastases.

Epidemiology

The incidence is estimated at less than 0.5% of the pituitary symptomatic tumors .

Clinical presentation

They are usually diagnosed as invasive macroadenomas and for such have the similar clinical presentation.

Pathology

Pituitary carcinomas are composed of adenohypophysial cells and do not show obvious microscopic features of malignancy. The majority are hormonally active .

Metastases may occur through the adjacent lymphatic and vascular spaces, hematogeneously, or from invasion into the subarachnoid space.

Radiographic features

They are indistinguishable from pituitary macroadenomas on imaging, and local invasion to the cavernous sinus and adjacent structures are features of both tumors. The diagnosis may be inferred when metastases are identified.

Nuclear medicine

Positron emission tomography scan using 18F-labeled deoxyglucose have been used for staging and follow-up of the metastatic lesions.

Treatment and prognosis

These tumors have a poor prognosis with a reported mean survival time between 1 to 2 years .

Differential diagnosis

  • metastasis to the pituitary gland
    • as pituitary carcinomas are a rare entity, it is more reasonable to consider other primary sites in patients presenting with a pituitary lesion and concomitant peripheral metastases