Pituitary GlandPituitary Gland

The normal microscopic appearance of the pituitary gland

The normal microscopic appearance of the pituitary gland

The adenohypophysis

The adenohypophysis

The neurohypophysis

The adenohypophysis contains three major cell types:

Cell types and functionCell types and function

• Somatotroph GH

• Mammotroph Prl

• Corticotroph ACTH

• Gonadotroph LH , FSH

• Thyrotroph TSH

• Null cells non-function

Hyperpituitarism - AdenomaHyperpituitarism - Adenoma

• Excess hormone production by the anterior lobe majority are Adenomas

• Hyperplasia and carcinoma are rare

Morphology of AdenomaMorphology of Adenoma

• Single and encapsulated• Microadenoma is lesser than 1 cm• Macroadenoma is larger than 1 cm , may reach

up to 10 cm• May show cystic changes and foci of necrosis • Expand sella tursica pressure effects (optic

chaisma )

• Pituitary apoplexy = haemorrage in the adenoma

HistologyHistology

Sheets of uniform rounded cells with delicate scanty stroma

Immunohistochimistry : Type of secertory hormone

Types of Pitutary adenomaTypes of Pitutary adenoma

Growth hormone producing Growth hormone producing adenoma (5%)adenoma (5%)

• Usually large

• Evenly distributed into densely and sparsely granulated types

• E/M spherical cytoplasmic granules

• Immuno positive GH - Gh 1/3 and PRL

• Acidophilic cells

Growth hormone producing adenoma (5%)

• Gigantism (children)

• Acromegaly (adults)

• glucose intolrence , DM,osteoprosis, hypertension

Prolactin producing adenoma Prolactin producing adenoma (20-30%)(20-30%)

• The most common functioning adenoma • Majority are microadenamas and sparsely

granulated • E/M : small secretory granules • Immuon:+sv PRL• Women ---- microadenomas (amenorrhoea,

glactorrhea syndrom )• Men and old females ------ macroadenoam(late

discovery)-----mass effect

Non secretory (Null cell ) adenoma Non secretory (Null cell ) adenoma (20%)(20%)

• Commenest cause of hypopituitarism

• Large ( macroadenoma) with atrophy of the surrounding pituitary tissue

• Immuno Variable 1/3 negative

• Chromphobic cells

Other rare types of adenomasOther rare types of adenomas

• ACTH producing adenoma

• FSH and LH – producing adenoma

• TSH-Producing adenoma

• Mixed

ACTH producing adenomaACTH producing adenoma

• Usually microadenomas

• Give rise to Cushing’s disease

• E/M: +ve ACTH

• Basophilic cells

• Nelson’syndrome(bilatral adrenalectomy----secondry ACTH- producing pituitary adenoma

FSH and LH – producing adenomaFSH and LH – producing adenoma

• Usually large

• No clinical features due to FSH and LH \

• Mass effect

• High serum FSH and Lh

• E/M : secretary granules( 250 nm)

• Immuno : +ve FSH and LH

• Basophile cells

TSH-Producing adenomaTSH-Producing adenoma

• Rare

• Produce TSH

Carcinoma of the pituitaryCarcinoma of the pituitary

• Rare and non functioning• Differentaited from adenoma by metastasis

HypopituitarismHypopituitarism

• Causes:

• Non_secrertory adenoma

• Pituitary necrosis (sheehan’s syndrom)

• The empty sella syndrome• Pituiraty destruction (infection,

radiation,surgical ablation,metastasis,vasculitis)

• Clinical features :

• Deficiency of Gh : Dwarfism (children)

• Deficiency of Gonadotrophins : stereility

• Deficiency of ACTH or TSH : Hypofunction of the relevant endocrine glande

Posterior pituitary syndromesPosterior pituitary syndromes

• Rare

• Due to hypothalamic tumors (gliaoma,gangliocytoma,craniopharyngioma,GCT)

• Deficiency of antidiuretic hormone (ADH Deficiency)----- diabetes insipidus pyolyuria=polydipsia