Endocrine Abstracts

Background: Invasive pituitary tumors may behaviour like some pituitary carcinomas. Although invasiveness is not indicative of malignancy, it probably puts the patient at higher risk of developing a pituitary carcinoma. These are very rare and the diagnosis requires evidence of metastatic disease, either cerebrospinal or extracranial. Although de novo development cannot be excluded they usually present as typical pituitary adenomas, which reveal their malignant character only as time progresses.

Case: We describe a 35-year-old woman who presented with a prolactin-secreting pituitary macroadenoma with suprasselar extension, left cavernous sinus and sphenoid sinus invasion and without pituitary insufficiency. Five years later, after the diagnosis, the tumor developed an invasive behaviour with pathological (nuclear pleomorphism, mitotic figures, necrosis and bone invasion) and immunohistochemical studies indicating a highly proliferative activity, aggressive growth and malignant potential (ki-67>3% and a p53 expression that revealed scarce nuclear immunostaining). She underwent medical therapy during the first years, four pituitary surgeries, all of them with early recurrence, and radiotherapy. She died approximately nine years after the initial diagnosis and four years following the first pituitary surgery. No proven site metastasis was detected.

Conclusion: This case highlights the poor prognosis of this type of tumors. The clinico-pathological course in itself should alert clinicians for the tumor to be labelled as aggressive and/or potential malignant. Ki-67 labelling indices in combination with p53 nuclear staining have been shown to correlate with invasiveness growth and aggressive/malignant behaviour. It is, therefore, important to perform these markers in invasive macroadenomas in order to predict the subset of tumors with the most aggressive behaviour. All available treatments should be applied, early in the course of the disease, in an attempt to prolong a better survival rate.