Metastatic pituitary carcinoma in a patient with acromegaly: a case report.

INTRODUCTION: Asymptomatic pituitary abnormalities occur in about 10% of cranial magnetic resonance imaging scans, but metastatic carcinoma of the pituitary gland is rare: 133 cases have been reported. Two thirds secreted either prolactin or adrenocorticotropic hormone, and another 24% were non-secreting.

CASE PRESENTATION: A 42-year-old Caucasian man lived for 30 years after the diagnosis of a pituitary tumor whose clinical and biochemical features were those of acromegaly and hypogonadism. Radiotherapy, totaling 7300 rad, was administered to the sella over two courses. Growth hormone levels normalized, but he developed both thyroid and adrenal insufficiency, and replacement therapy was commenced. Fourteen years later, growth hormone levels again became elevated, and bromocriptine was commenced but led to side effects that could not be tolerated. An attempted surgical intervention failed, and octreotide and pergolide were used in succession. Twenty-seven years after the diagnosis, a mass from an excisional biopsy of below the angle of the mandible proved to be metastatic pituitary carcinoma. Immunohistochemical staining was positive for synaptophysin, growth hormone, and prolactin. One year later, an octreotide scan showed uptake at the sella, neck, and spleen. Our patient declined further active oncology treatment.

CONCLUSIONS: Metastatic pituitary carcinoma associated with acromegaly is particularly rare. To the best of our knowledge, this is the eighth such case and is the first report of growth hormone and prolactin present in the metastatic mass.