Pituitary adenomas are common, accounting for approximately 15% of intracranial tumours. They are monoclonal, produced by genetic and epigenetic alterations— leading to activation of proto- oncogenes or inactivation of tumour suppressor genes— that impart growth and survival advantage to a single cell. While the majority of the tumours are sporadic, some are associated with familial syndromes exhibiting different genetic background and variable phenotype; germline, somatic, and mosaic mutations have been identified (see Table 1).

Table1. Clinicopathologic features of germline, somatic, and mosaic mutations in pituitary adenomas

Pituitary tumours may be referred to as microadenomas (less than 10 mm in diameter), or macroadenomas (greater than 10 mm in diameter). The growth pattern of these tumours may be expansive resulting in a slowly growing mass exerting increasing pressure on the surrounding healthy gland and the bony sella. In contrast, invasive adenomas spread into the surrounding normal gland, dura or other parasellar structures (sphenoid sinus, cavernous sinus) regardless of their size. Adenomas extending into the suprasellar space may compress the optic chiasm causing visual disturbances, a frequent clinical manifestation of macroadenomas.

When interpreting pituitary pathology, the clinical and radio logical information must be considered as a whole. At the time of surgery, gentle tissue handling is recommended with prompt and appropriate fixation of the specimen in formalin for pathological study. It is optional that a small fragment of tissue be fixed in glutaraldehyde, osmicated, and embedded for electron microscopy for cases that are difficult to diagnosis. It may also be worthwhile to obtain DNA from the patient’s blood before surgery and freeze a portion of the tumour for subsequent molecular and DNA analysis.

A logical order of steps must be followed to study the morphology of pituitary adenomas. It is essential to first establish whether the tissue obtained is from a normal pituitary gland, a pituitary tumour, or a different sellar lesion. Next, immunohistochemical classification based on hormone production by the cells is accomplished and, finally, prognostic information and treatment options can be determined by analysing various biomarkers and by molecular/ genetic/ epigenetic investigation (See Table 2).

Table2. Panel approach for the evaluation and diagnosis of pituitary adenomas

By histology, adenomas are acidophilic, basophilic, or chromophobic. The tinctorial properties of tumours are largely un related to their hormonal function. After initial evaluation using the haematoxylin & eosin (H&E) stain, which allows distinction from other pathologies of the sellar region, the next step is to demonstrate the absence of reticulin fibres. This differentiates normal adenohypophysis from hyperplasia or adenoma. The normal acinar reticular pattern is enlarged but intact in cases of hyperplasia and, regardless of their size, a total dissolution of the acinar architecture is evident in every adenoma. PAS stain is used to recognize corticotrophs because of the carbohydrate moiety present in POMC which is the precursor of ACTH. Chromogranin and synaptophysin, broad- spectrum endocrine markers, are used to confirm that the lesion is of endocrine origin. Cam5.2, a low molecular weight keratin, is used to identify and confirm somatotroph and corticotroph adenomas. They are immunopositive, and the keratin pattern will help to clarify their subtype: diffuse perinuclear, paranuclear globular (dot pattern), mixed or ring- like. These characteristic patterns are specific to certain adenoma types.

The current World Health Organization (WHO) classification (2017) of pituitary adenomas recommends the use of pituitary adenohypophyseal cell lineages for their classification rather than according to their hormone production. Accordingly, pituitary adenoma classification uses a wide range of monoclonal antibodies against pituitary hormones, and pituitary transcription factors, to differentiate the various tumour cell types. Electron microscopy, although useful, is currently only utilized in cases that are difficult to diagnose. The available immunohistochemical stains used for studying pituitary adenomas and their utility are presented in Table 2.

اخر الاخبار

اخبار العتبة العباسية المقدسة

بيان صادر عن العتبة العباسية المقدسة

قسم التطوير يقيم دورة تدريبية عن الهندسة النفسية لملاكاته

تضررت في الانتفاضة الشعبانية.. الكشف عن قطع تاريخية من الإيوان الذهبي لمرقد أبي الفضل العباس (عليه السلام)

قسم الصناعات ينهي أعمال صيانة منظومة التهوية في مجمع أبي الفضل العباس (عليه السلام)

المزيد

الآخبار الصحية

عادات يومية تدمر قلبك بصمت.. خبراء يطلقون التحذير

خبراء تغذية يكشفون "أفضل وقت لتناول الإفطار"

أطعمة تزيد فرص وفاة مرضى السرطان 60 بالمئة.. ما هي؟

اختبار ثوري جديد يكشف مبكرا عن سرطان البنكرياس

المزيد

الآخبار التكنلوجية

الذكور أم الإناث؟ دراسة "تنسف الشائع" بشأن التوحد

خبير يكشف عن اقتراب العلماء من فك شفرات "لغات الحيوانات" !

دراسة تدفعك لشراء ساعة ذكية "فورا".. هذا ما تقوله عن قلبك

علماء حاصلون على "نوبل": الذكاء الاصطناعي لن يستبدل الإنسان

المزيد

مواضيع ذات صلة

T pit Family of tumours

Pit- 1 Family of tumours

Molecular Mechanisms of Carcinogenesis

Chronic Myeloid Leukemia, BCR-ABL Gene, and Disease Monitoring

Application of Liquid Biopsy to Non-small- Cell Lung Cancer Lung

Circulating Tumor DNA

Biomarkers in the Blood and in Tissues: A Complementary Approach

Biomarkers in Oncology: An Evolving Concept

Clinical Development of Venetoclax for Acute Myeloid Leukemia

Clinical Development of Oblimersen for Acute Myeloid Leukemia

Modalities for treating cancer

Tumor markers