null-cell adenoma(redirected from undifferentiated cell adenoma)
a benign epithelial tumor in which the cells form recognizable glandular structures or in which the cells are derived from glandular epithelium.
acidophilic adenoma in a classification system formerly used for pituitary adenomas, an adenoma whose cells stain pale pink with acid dyes; most adenomas that secreted excessive amounts of growth hormone were in this group
ACTH-secreting adenoma (adrenocorticotrophic hormone–secreting adenoma) corticotroph adenoma.
basophilic adenoma in a classification system formerly used for pituitary adenomas, an adenoma whose cells stain pale blue with basic dyes; most adenomas that secreted excessive amounts of adrenocorticotrophic hormone were in this group.
chromophobe adenoma (chromophobic adenoma) a pituitary adenoma composed of cells that lack acidophilic or basophilic granules; this is the same entity as the more precisely named null-cell a.
corticotrope adenoma (corticotroph adenoma) a pituitary adenoma made up predominantly of corticotrophs; excessive corticotropin secretion may cause Cushing's disease or Nelson's syndrome. Called also ACTH-secreting or adrenocorticotropic hormone–secreting adenoma and corticotropinoma.
endocrine-active adenoma a pituitary adenoma that secretes excessive amounts of a hormone; see prolactinoma, corticotroph adenoma, gonadotroph adenoma, growth hormone–secreting adenoma, and thyrotroph adenoma. Called also hyperfunctional or hyperfunctioning adenoma.
endocrine-inactive adenoma a pituitary adenoma that does not secrete excessive amounts of any hormone; many null-cell adenomas are of this type. Called also nonfunctional or nonfunctioning adenoma and nonsecreting or nonsecretory adenoma.
eosinophilic adenoma growth hormone–secreting adenoma.
gonadotrope adenoma (gonadotroph adenoma) a rare type of pituitary adenoma made up of gonadotroph-like cells that secrete excessive amounts of follicle-stimulating hormone or luteinizing hormone or both; it may cause precocious puberty, visual disturbances, or hypogonadism.
growth hormone–secreting adenoma a pituitary adenoma made up of somatotroph-like cells that secrete excessive amounts of growth hormone; it may cause gigantism in children or acromegaly in adults. Called also somatotrope or somatotroph adenoma and eosinophilic adenoma.
hepatocellular adenoma a large, fleshy, hypervascular tumor of the liver occurring chiefly in women of childbearing age and associated with oral contraceptive use. It is composed of sheets of cells with areas of hemorrhage and necrosis and has a tendency to hemorrhage and rupture; it may become malignant.
Hürthle cell adenoma a benign hürthle cell tumor.
hyperfunctional adenoma (hyperfunctioning adenoma) endocrine-active adenoma.
lactotrope adenoma (lactotroph adenoma) prolactinoma.
liver cell adenoma hepatocellular adenoma.
nonfunctional adenoma (nonfunctioning adenoma) endocrine-inactive adenoma.
nonsecreting adenoma (nonsecretory adenoma) endocrine-inactive adenoma.
null-cell adenoma a pituitary adenoma whose cells give negative results on tests for staining and hormone secretion; although classically they were considered to be composed of sparsely granulated or degranulated (nonfunctioning) cells, some contain functioning cells and may be associated with a hyperpituitary state such as acromegaly or Cushing's syndrome. These tumors are often discovered clinically only when they have grown large and are pressing on surrounding structures. Called also chromophobic adenoma.
pituitary adenoma a benign neoplasm of the anterior pituitary gland; some contain hormone-secreting cells (endocrine-active adenomas) but some are not secretory (endocrine-inactive adenomas).
plurihormonal adenoma an endocrine-active adenoma that secretes more than one kind of hormone.
prolactin cell adenoma (prolactin-secreting adenoma) prolactinoma.
sebaceous adenoma hypertrophy or benign hyperplasia of a sebaceous (oil-secreting) gland.
adenoma seba´ceum nevoid hyperplasia of sebaceous glands, forming multiple yellow papules or nodules on the face. See also nevus.
somatotrope adenoma (somatotroph adenoma) growth hormone–secreting adenoma.
thyroid-stimulating hormone–secreting adenoma thyrotroph adenoma.
thyrotrope adenoma (thyrotroph adenoma) (TSH-secreting adenoma) a rare type of pituitary adenoma made up of thyrotroph-like cells that secrete excess thyrotropin and cause hyperthyroidism; called also thyroid stimulating hormone–secreting adenoma.
villous adenoma a large soft papillary polyp on the mucosa of the large intestine.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
an adenoma of the hypophysis composed of cells for which there is no overt evidence of hormone production, but which usually produces hypopituitarism and visual disturbances by compression of adjacent structures; approximately one third of these tumors have cells with abundant mitochondria (oncocytes) that are somewhat larger than the monocytic null cells.
Synonym(s): undifferentiated cell adenoma
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