What is a pituitary adenoma ?
Pituitary adenomas are benign tumors originating in the pituitary gland.
Their treatment is sometimes complex but the prognosis is good in the vast majority of cases.
What are the symptoms ?
Pituitary adenomas are often discovered incidentally during brain imaging (CT or MRI) for another reason.
Pituitary adenomas can cause 3 main types of symptoms depending on their type and size:
A pituitary tumor syndrome, linked to the compression that the tumor exerts on neighboring structures and which can lead to,
- visual disturbances (linked to the compression of the optic chiasma located a few millimeters above the pituitary gland):
– Reduction of the visual field;
– Decreased visual acuity;
- headache or headache;
- a syndrome of the cavernous sinus compartment by compression of the nerves which travel along the pituitary gland in the cavernous sinus and which control the movements of the eyes. It is most often a double vision or a fall of the eyelid. These symptoms are rare in pituitary adenomas and most often indicate sudden necrosis and / or bleeding in a tumor.
Hormonal hypersecretion syndromes: Pituitary adenomas can also manifest as signs of hypersecretion of a hormone by the tumor.
- hypersecretion of prolactin or hyperprolactinaemia responsible for a disappearance of menstruation (secondary amenorrhea), a milky secretion of the breasts (galactorrhea) or sexual disorders,
- acromegaly secondary to hypersecretion of growth hormone, responsible for a gradual and insidious thickening of the face and extremities, hypersudation, carpal tunnel syndrome, joint pain, hypertension or high blood pressure, diabetes,
- hypercorticism (Cushing’s syndrome) secondary to hypersecretion of ACTH stimulating the adrenal cortisol production and which present with android obesity together with high blood pressure, diabetes, fatigue, flushing of the face and sometimes psychiatric disorders.
- more rarely, hyperthyroidism secondary to hypersecretion of TSH by a thyreotropic adenoma.
An anterior pituitary insufficiency syndrome, usually involving all the hormones normally secreted by the pituitary gland. A defect in the secretion of anterior pituitary hormones (hypopituitarism) results when it is global by fatigue, pallor, sexual disorders, thin skin. The growth hormone deficiency in children leads to growth retardation. Thyroid hormone deficiency causes pallor, weight gain, constipation and depression. Gonadotropic insufficiency is linked to a decrease in the production of hormones which stimulate the production of sex hormone by the ovaries and testes. It causes signs of hypogonadism (absence of puberty, amenorrhea, impotence, infertility); Corticotropic insufficiency, the most life-threatening, leads to asthenia, low blood pressure and digestive disorders in the event of decompensation.In front of these symptoms, the clinical analysis makes it possible to orient towards a pituitary pathology and in the event of suspicion, a biological assessment will be carried out in priority. When this suspicion is confirmed, the reference radiological examination is the pituitary MRI.
Classification of pituitary adenomas
There are several histological subtypes corresponding to the different clinical pictures:
- Secreting or functional adenomas
– Prolactin adenoma (PRL) is the most frequent and represents 60% of all adenomas (female-male ratio: 10/1, average age at diagnosis of 32 years)
– The somatotropic adenoma secreting growth hormone (GH) represents approximately 13% of all adenomas; the age at the time of diagnosis is 47 years, with a frequent variant somatoprolactinic adenoma, secreting PRL and GH (50% of somatotropic adenomas).
– The corticotropic adenoma is most often small (<10mm) or “micro-adenomas” and secretes ACTH. It represents 6% of all adenomas. Macroadenomas are less common.
– Thyrotropic adenoma secreting TSH is rare (<1% of all adenomas). It is most often accompanied by hyperthyroidism, but it can be silent and multisecretory (TSH-GH and TSH-PRL).
- Non-secreting or non-functional adenomas: They represent 30% of pituitary adenomas. The term “non-functional” should be preferred, because in about a third of cases, there is a hormonal expression, without clinical translation, but which can serve as a biological marker. These tumors are mostly gonadotropic adenomas.
- Silent adenomas
They are less common. These are adenomas revealed by a tumor compression syndrome without a specific clinical picture of hypersecretion, but which in immunocytochemistry are positive for ACTH, GH, or TSH or even multi-hormonal (GH and PRL or TSH and GH ). Biologically, either they do not secrete a hormone, or more frequently, they secrete an inactive pro-hormone explaining the absence of clinical signs or a hormone in small quantity, but dosable (hypersecretion of ACTH without hypercorticism is there ‘most frequent example)
- Aggressive or atypical adenomas and carcinomas
The frequency of aggressive adenomas is still unknown. Only 0.2% of tumors show metastases during evolution and are considered to be carcinomas: most secreting – 36% PRL, 30% ACTH – and only 23% non-secreting. These never inaugural metastases occur 5 to 16 years after the start of clinical history and concern either the nervous system with dissemination by cerebrospinal fluid (CSF) or various organs: lungs, bones, liver or even lymph nodes.
Who is concerned ?
Pituitary adenomas represent between 10 and 20% of intracranial tumors in adults. These tumors have an incidence of 4/100 000 inhabitants with an increasing tendency for incidental discoveries, “incidentalomas”.
It is a rare tumor (2.7% of supratentorial tumors) in children whose most common pituitary tumor is craniopharyngioma.
How is the diagnosis made ?
In front of a set of endocrine and \ or neurological and \ or ophthalmological symptoms, your doctor will request a brain MRI which will confirm the existence of a pituitary lesion; this will result in a consultation with a neurosurgeon or an endocrinologist.
- The endocrine assessment
The endocrine assessment will be launched either because the patient has an endocrine syndrom or because a lesion of the pituitary region has been discovered in the imaging exams. This assessment routinely includes the determination of the main hormonal axes (Prolactin; TSHus; T4l; T3l; FSH; LH; Estradiol / Testosterone; GH; Igf1; Cortisolemia).
The endocrinology consultation with our endocrinologist, will be organized preoperatively in the case of secreting pituitary adenomas or in case of hormonal insufficiencies. If necessary, hormone replacement therapy can be considered before the intervention.
- The radiological assessment
Brain MRI remains the gold standard to explore pituitary lesions. This examination must be optimal in order to have a precise anatomical description, making it possible to define the limits of the adenoma with: its extension in sella turcica, the sphenoid sinus, the diaphragma sellae above, the cavernous sinuses laterally, toward the chiasma and the diencephalon.
The brain CT with an angioscanner in bone windows can be requested and used for neuronavigation to guide the surgical intervention. This examination provides additional information, especially on the bone involvment..
The radiological semiology of the pituitary region is very rich and requires an experienced radiologist. For this, the files are reviewed with our reference neuro-radiologist.
- Neuro-ophthalmological assessment
Neuro-ophthalmological syndrome will be explored based on the patient’s visual complaint and especially the extension of the pituitary adenoma to the opto-chiasmatic pathways and \ or to the cavernous sinus on the brain MRI. The neuro-ophthalmological examination will include visual acuity and visual field to assess the compression of the optic nerves and a Lancaster test if comression to the oculomotor nerves is suspected.
What are the treatments available?
Treatment can consist of :
- neuroradiological monitoring in the event of non-secreting adenoma;
- medical treatment in functional adenomas when there is the possibility of antagonistic treatment; in this case, the patient is referred to an endocrinologist;
- surgery in case of growing adenomas, adenomas resistant to treatment, adenomas with compression of the opto-chiasmatic pathways;
- radiotherapy for inoperable adenomas, postoperative residues and aggressive adenomas.
Why endoscopic endonasal surgery?
Currently, the vast majority of pituitary adenomas are operated on through an endoscopic endonasal approach. Unlike the microscope, where the surgeon’s eye remains outside the nose, giving only a very limited vision of the nasal cavities, the endoscope brings the surgeon’s eye to the bottom of the cavities and allows a panoramic view of the lesion. It also allows with 30 and 45 ° endoscopes to see laterally and upwards and therefore, to better appreciate and remove the possible extensions of the tumor. The use of minimally invasive routes respecting the nasal cavities has made it possible to significantly reduce the rhinological morbidity of this surgery and to increase the postoperative comfort of patients.
Preoperative consultations and assessment
- Radiological assessment,
- Consultation with the endocrinologist,
- Neuro-ophthalmological consultation if necessary,
- Anesthesia consultation in case of surgical intervention.