Endocrine Pathology 1 Flashcards
pituitary adenomas - overview
*benign epithelial neoplasm arising from anterior pituitary gland
*most common cause of HYPERpituitarism
pituitary adenomas - classifications
*pituitary adenomas are classified based on:
1. size: micro-adenomas (small, < 1 cm) vs. macro-adenomas (large, > 1 cm)
2. hormone production:
-functional = cause clinical syndromes related to overproduction of hormone(s)
-nonfunctional = cause mass effect due to growing to larger size before detection
pituitary adenomas - clinical features
*systemic: dependent on excess or deficiency of pituitary hormones
*local: dependent on mass effects:
-visual field abnormalities (bitemporal hemianopsia) due to compression of optic chiasm
-headache, N/V are signs of elevated intracranial pressure
pituitary adenomas - pathogenesis
- sporadic/acquired somatic mutations:
-growth hormone releasing hormone receptor (GHRHR)
-ubiquitin-specific protease 8 (USP8) - familial/inherited: MEN1 germline mutations
pituitary adenomas - pathologic features
*solitary, well-circumscribed lesions
*monotonous cells with decreased or no supporting reticulin stroma
*immunohistochemical stains identify the hormones
subtypes of pituitary adenomas: lactotroph adenoma
*hormone = prolactin
*associated syndrome = galactorrhea & amenorrhea (in females); sexual dysfunction, infertility
subtypes of pituitary adenomas: somatotroph adenoma
*hormone = growth hormone (GH)
*associated syndrome = gigantism (children), acromegaly (adults)
subtypes of pituitary adenomas: mammosomatotroph adenoma
*hormone = prolactin, GH
*associated syndrome = combined features of growth hormone and prolactin excess
subtypes of pituitary adenomas: corticotroph adenoma
*hormone = ACTH and other POMC-derived peptides
*associated syndrome = Cushing syndrome, mass effect
subtypes of pituitary adenomas: thyrotroph adenoma
*hormone = TSH
*associated syndrome = hyperthyroidism
subtypes of pituitary adenomas: gonadotroph adenoma
*hormone = FSH, LH
*associated syndrome = hypogonadism (most are silent with mass effect)
craniopharyngioma - overview
*epithelial neoplasm arising from Rathke pouch remnants
*proliferation of squamous cells
craniopharyngioma - clinical features
*bimodal distribution: children 5-15 years; elderly > 65
*headaches and visual disturbances
*suprasellar (may induce hypo- or hyper-function of pituitary, diabetes insipidus; children may have growth retardation)
craniopharyngioma - pathologic features
*keratinizing squamous cells, calcifications, cholesterol crystals, fibrosis
*associated mutations:
1. BRAF mutations → papillary architecture
2. beta-catenin mutations → compact, lamellar (“wet”) squamous epithelium with peripheral palisading
thyroid gland - overview
*2 lobes united by an isthmus
*only endocrine organ which stores secretory product
*synthesizes hormones:
-thyroxine (T4) and tri-iodothyronine (T3) = controls basal metabolic rate in cells
-calcitonin = inhibits osteoclast activity
thyroid gland - cell types
- follicular cells:
-simple cuboidal epithelium, under the control of TSH
-exocrine function = thyroglobulin (colloid) production; sufficient stored hormone to supply body ~3 months
-endocrine function = iodination of thyroglobulin with subsequent secretion of T4 and T3 - parafollicular (C) cells:
-neuroendocrine cells which secrete calcitonin
-triggered by elevated blood Ca2+
-inhibits osteoclast activity
goiter - overview
*enlargement of the thyroid
*most common clinical manifestation of thyroid disease
goiter - pathogenesis
*defective synthesis of T3 and T4 from relative iodine deficiency
*endemic = dietary iodine deficiency
*sporadic goiter = most common in adolescent/young adult women; dietary goitrogens
goiter - pathology
*diffuse goiter evolves into multinodular goiter
1. initial diffuse goiter (TSH-induced proliferation of follicular cells → cells involute as demand for thyroid hormones goes down)
2. cycles of proliferation/involution → irregular enlargement
goiter - clinical features
*usually functionally silent (euthryoid)
*neck mass may become so large it compresses other structures → airway obstruction, dysphagia, and vascular compromise
pathogenesis of thyroid enlargement in Graves’ Disease
- IgG antibodies to TSH receptor →
- bind to follicular cells →
- thyroid hypertrophy/hyperplasia →
- increased secretion of T3 and T4
Graves Disease - overview
*most common cause of hyperthyroidism
*most prevalent in women of childbearing age
*associated with HLA-DR3
*caused by autoantibodies against TSH receptor, which bind to and stimulate thyroid follicular cells