Aggressive Pituitary Tumors or Localized Pituitary Carcinomas: Defining Pituitary Tumors

ABSTRACT

Pituitary tumors are common and exhibit a wide spectrum of hormonal, proliferative and invasive behaviors. Traditional classifications consider them malignant only when they exhibit metastasis. Patients who suffer morbidity and mortality from aggressive tumors classified as “adenomas” are denied support provided to patients with “cancers” and in many jurisdictions, these tumors are considered curiosities that do not warrant reporting in health registries. We propose use of the term “tumor” rather than “adenoma” to align with other neuroendocrine tumors. The features that can serve as diagnostic, prognostic and predictive markers are reviewed. Clinico-pathological and radiographic classifications provide important information and to date, no single biomarker has been able to offer valuable insight to guide the management of patients with pituitary tumors.

KEY WORDS:

• Pituitary
• neoplasia
• benign
• malignant
• classification
• morphology
• biomarkers

Financial and competing interests disclosure

S.L. Asa is on the medical advisory board for Leica Aperio. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Pituitary tumors are common with increasingly recognized clinical prevalence.

• The current criteria for the diagnosis of malignancy are inappropriate for the morbidity and mortality of these neoplasms; the terminology ‘tumor’ should be applied as in other neuroendocrine neoplasms rather than relegating them to the status of benign adenomas

• Advanced imaging techniques offer improved therapeutic surgical planning.

• Histopathologic features provide the basis for tumor classification.

• Histopathologic features currently offer the most reliable prognostic and predictive information.

• Multiple medical modalities are available for control of hormone excess and in some cases can restrain tumor progression.

• Numerous biomarkers have been proposed but remain to be validated for reliable and reproducible clinical applications.

• Evolving genetic and epigenetic information will need to be integrated within the broader spectrum of neuroendocrine neoplasia.