1. Clinical and endocrinological classification Pituitary adenomas are classified into functional and nonfunctional categories according to the secretory activity of the tumor in the body. Functional pituitary adenomas include prolactin adenomas, growth hormone adenomas, adrenocorticotropic hormone adenomas, and thyrotropin adenomas. Non-functional adenomas include gonadotrophic adenomas, naked cell adenomas and eosinophilic adenomas.
2. Pathological classification According to conventional pathological classification, they are classified as eosinophilic, basophilic and suspicious. The gold standard for classification of pituitary adenomas is based on immunohistology and electron microscopic observation.
Describing tumors based on ultrastructure, hormonal components and cellular derivatives is an approach that combines structure, function, cellular origin and biological properties. This approach divides pituitary adenomas into 14 subtypes, each with its own ultrastructural and immunohistochemical characteristics. Pituitary adenomas are first classified according to cellular origin and hormonal components, and then classified into subtypes according to ultrastructural characteristics.
3. Imaging classification According to the size of the tumor, it is divided into microadenoma and macroadenoma. Pituitary microadenoma is 10mm, pituitary macroadenoma is R10mm and pituitary macroadenoma is R40mm. microadenoma is classified into grade 0 and grade I according to whether there is any change in the shape of the pterygoid saddle. Macroadenomas were classified into grade II, III and IV according to the degree of destruction inside and outside the pterygoid saddle. Macroadenomas are further divided into subtypes according to the degree and direction of expansion outside the pterygoid saddle.
WHO classification of pituitary adenomas is based on five criteria: (1) clinical presentation and secretory activity (e.g. acromegaly).
(2) Volume and aggressiveness (e.g. Hardy classification).
(3) Histological features (e.g., typical or atypical tissue).
(4) Immunohistochemical features.
(5) Ultrastructural subtypes.