Improving differential diagnosis of pituitary adenomas

Abstract

Pituitary adenomas are common tumors arising in adenohypophysial cells or their precursors. For improving control of the disease an early diagnosis is important. Initially considered sporadic tumors, some of them are associated with familial syndromes and their recognition and classification is also required. Morphologically, pituitary adenomas represent a heterogeneous group of tumors with several subtypes and different clinical behavior thus a precise pathological diagnosis is crucial. The simple diagnosis of pituitary adenoma is not satisfactory and the correct classification of histological subtypes may predict aggressiveness in the majority of cases. Although considered not malignant, some of them are clinically aggressive and their recognition remains a challenge. In this paper we present the recent advances in the event of improving early recognition and differential diagnosis of pituitary tumors.

Keywords::

• classification
• diagnosis
• familial syndrome
• genetics
• pathology
• pituitary adenoma

Financial & competing interests disclosure

The authors are grateful to the Jarislowsky and Lloyd Carr-Harris Foundations for their generous support. The authors have no 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. This includes employment, honoraria, stock ownership or options, expert testimony, patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Pituitary adenomas were considered sporadic tumors, but in the last few years familial pituitary adenomas have been recognized.

• Multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, Carney complex, familial isolated pituitary adenoma and mutations in DICER1 and succinate dehydrogenase genes are the most common familial syndromes.

• High-field MRI (3 Tesla) seems superior to standard MRI for preoperative evaluation of pituitary adenomas.

• An algorithmic approach or logical and rational order of steps must be followed studying the pathologic assessment of pituitary adenomas. The first one is to prove that the submitted specimen for morphologic investigation is a pituitary adenoma. Subsequently, the classification of the tumor based on their hormone production is accomplished. Finally, the behavior and potential therapy and prognosis should be determined.

• WHO categorizes pituitary tumors as typical pituitary adenoma, atypical pituitary adenoma and pituitary carcinoma. This classification is not correlated with clinical behavior. The conclusive classification of histological subtypes is important for predicting clinically aggressive behavior.

• Tumors with aggressive clinical behavior are most often sparsely granulated somatotroph adenomas, acidophil stem cell adenomas, silent corticotroph adenomas, Crooke’s cell adenomas, thyrotroph adenomas or silent subtype 3 adenomas.

• In difficult cases or in the absence of identifiable hormone content, pituitary-specific transcription factor 1, t-box transcription factor, steroidogenic factor, estrogen receptor α and GATA binding protein 2 may help to identify and differentiate the tumor.

Notes