Most common type of pituitary adenoma?
Correct Answer: Prolactinoma
Description: Ans. D. Prolactinoma. (Ref. H - 17th / pg. 2204)# Most common type of pituitary adenoma is Prolactinoma.PITUITARY TUMORS# Pituitary adenomas are the most common cause of pituitary hormone hypersecretion and hyposecretion syndromes in adults. They account for -15% of all intracranial neoplasms.Pathogenesis:# Pituitary adenomas are benign neoplasms that arise from one of the five anterior pituitary cell types - tumors arising from lactotrope (PRL), somatotrope (GH), corticotrope (ACTH), thyrotrope (TSH), or gonadotrope (LH, FSH) cells hypersecrete their respective hormones, with prolactinomas being the most common variety.# Several familial syndromes are associated with pituitary tumors, like Multiple endocrine neoplasia (MEN) 1, Carney syndrome, MeCline-Albright syndrome and Familial acromegaly.C/f:Features of Sellar Mass Lesions:Impacted StructureClinical ImpactPituitaryHypogonadism, Hypothyroidism, Growth failure and adult hyposomatotropism, HypoadrenalismOptic chiasmLoss of red perception, Bitemporal hemianopia, Superior or bitemporal field defect, Scotoma, BlindnessHypothalamusTemperature dysregulation, Appetite and thirst disorders, Obesity, Diabetes insipidus, Sleep disorders, Behavioral dysfunction, Autonomic dysfunctionCavernous sinusOpthalmoplegia with or without ptosis or diplopia, Facial numbnessFrontal lobePersonality disorder, AnosmiaBrainHeadache, Hydrocephalus, Psychosis, Dementia,Laughing seizuresInvestigations# MRI: Sagittal and coronal T1-weighted MRI imaging, before and after administration of gadolinium, allow precise visualization of the pituitary gland with clear delineation of the hypothalamus, pituitary stalk, pituitary tissue and surrounding suprasellar cisterns, cavernous sinuses, sphenoid sinus, and optic chiasm. Pituitary gland height ranges from 6 mm in children to 8 mm in adults; during pregnancy and puberty, the height may reach 10-12 mm. The upper aspect of the adult pituitary is flat or slightly concave, but in adolescent and pregnant individuals, this surface may be convex, reflecting physiologic pituitary enlargement. The stalk should be midline and vertical. CT scan is indicated to define the extent of bony erosion or the presence of calcification.- Anterior pituitary gland soft tissue consistency is slightly heterogeneous on MRI, and signal intensity resembles that of brain matter on T1-weighted imaging. Adenoma density is usually lower than that of surrounding normal tissue on T1 -weighted imaging, and the signal intensity increases with T2-weighted images. The high phospholipid content of the posterior pituitary results in a "pituitary bright spot."Screening Tests for Functional Pituitary Adenomas TestCommentsAcromegalySerum IGF-IInterpret IGF-I relative to age- and gender-matched controls Oral glucose tolerance test with GH obtained at 0, 30, and 60 min Serum PRLNormal subjects should suppress growth hormone to <1 g/LProlactinomaExclude medications MRI of the sella should be ordered if prolactin is elevatedCushing's disease24-h urinary free cortisolEnsure urine collection is total and accurateDexamethasone (1 mg) at 11 P.M. and fasting plasma cortisol measured at 8 A.M.Normal subjects suppress to <5 g/dL ACTH assayDistinguishes adrenal adenoma (ACTH suppressed) from ectopic ACTH or Cushing's disease (ACTH normal or elevated)Rx:# MRI technology with gadolinium enhancement for pituitary visualization, new advances in transsphenoidal surgery and in stereotactic radiotherapy (including gamma-knife radiotherapy), and novel therapeutic agents have improved pituitary tumor management.# The goals of pituitary tumor Rx include normalization of excess pituitary secretion, amelioration of symptoms and signs of hormonal hypersecretion syndromes, and shrinkage or ablation of large tumor masses with relief of adjacent structure compression.# Residual anterior pituitary function should be preserved and can sometimes be restored by removing the tumor mass.Ideally, adenoma recurrence should be prevented.PROLACTINOMA# Introduction:- Tumors arising from lactotrope cells account for about half of all functioning pituitary tumors.- Hyperprolactinemia is the most common pituitary hormone hypersecretion syndrome in both men and women PRL-secreting pituitary adenomas (prolactinomas) are the most common cause of PRL levels >100 g/L. Less pronounced PRL elevation can also be seen with microprolactinomas but is more commonly caused by drugs, pituitary stalk compression, hypothyroidism, or renal failure.# C/f:- Amenorrhea, galactorrhea, and infertility are the hallmarks of hyperprolactinemia in women. If hyperprolactinemia develops prior to menarche, primary amenorrhea results.- If the tumor extends outside of the sella, visual field defects or other mass effects seen.- In men with hyperprolactinemia, diminished libido, infertility, or visual loss (from optic nerve compression) are the usual presenting symptoms. Gonadotropin suppression leads to reduced testosterone, impotence, and oligospermia.# Rx.:- As microadenomas rarely progress to become macroadenomas, no Rx may be needed if fertility is not desired. Estrogen replacement is indicated to prevent bone loss and other consequences of hypoestrogenemia and does not appear to increase the risk of tumor enlargement.- For symptomatic microadenomas, therapeutic goals include control of hyperprolactinemia, reduction of tumor size, restoration of menses and fertility, and resolution of galactorrhea.- Oral dopamine agonists (cabergoline or bromocriptine) are the mainstay of therapy for patients with micro- or macroprolactinomas.- Other Dopamine Agonists include pergolide mesylate, an ergot derivative with dopaminergic properties; lisuride, an ergot derivative; and quinagolide (CV 205-502, Norprolac), a nonergot oral dopamine agonist with specific D2 receptor activity.- Indications for surgical adenoma debulking include dopamine resistance or intolerance, or the presence of an invasive macroadenoma with compromised vision that fails to improve after drug Rx.
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