Pituitary adenoma classification
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Pituitary adenoma may be classified according to the size of the adenoma and type of hormone secretion, subtypes include corticotrophic, somatotrophic, thyrotrophic, gonadotrophic, and lactrotrophic adenomas.
- Historically, pituitary tumors were classified as basophilic, acidophilic, or chromophobic based on the positivity of hematoxylin and eosin stain.
- Newer classification is based on either the size or the functional status of the adenoma (secretory vs. non-secretory).
Classification based on hormone secretion and immunohistochemical staining
|Type of adenoma||Secretion||Staining||Pathology|
|Corticotrophic adenomas||Adrenocorticotropic hormone (ACTH) and pro-opiomelanocortin (POMC)||Basophilic||Cushing's disease|
|Somatotrophic adenomas||Growth hormone (GH)||Acidophilic||Acromegaly (gigantism)|
|Thyrotrophic adenomas (rare)||Thyroid-stimulating hormone (TSH)||Basophilic||Occasionally hyperthyroidism/Asymptomatic|
|Gonadotrophic adenomas||Luteinizing hormone (LH), follicle-stimulating hormone (FSH) and their subunits||Basophilic||Asymptomatic|
|Lactrotrophic adenomas or prolactinomas (most common)||Prolactin||Acidophilic||Galactorrhea, hypogonadism, amenorrhea, infertility, and impotence|
|Null cell adenomas||Do not secrete hormones||May stain positive for synaptophysin|
Classification based on the size of the adenoma
Pituitary adenoma may be classified into 4 grades based on radioanatomical:
- Stage I involves microadenomas (<1 cm) without sella expansion
- Stage II involves macroadenomas (≥1 cm) and may extend above the sella
- Stage III involves macroadenomas with enlargement and invasion of the floor or suprasellar extension
- Stage IV involves macroadenomas that cause destruction of the sella
- Pituitary adenoma (2015). http://www.cancer.gov/types/pituitary/hp/pituitary-treatment-pdq#section/_96. Accessed on 9/28/2015.