This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors of Nervous System, Subject name: Medicine
Most common tumour of pituitary' is - 
Select and explain. 
A. Prolactinoma, B. GH secreting adenoma, C. ACTH secreting adenoma, D. TSH secreting adenoma
A: Prolactinoma
Answer: A: Prolactinoma 
Explanation: Ans. is 'a' i.e., Prolactinoma Types of adenomasSecretionStainingPathology% of hormone production casesLacto trophicadenomas(prolactinomas)Secrete prolactinAcidophilicGalactorrhea, hypogonadism, amenorrhea, infertility, and impotence30%SomatotrophicadenomasSecrete growth hormone (GH)AcidophilicAcromegaly in adults; gigantism in children15%CorticotrophicadenomasSecrete adenocorticotropic hormone (ACTH)BasophilicCushing's disease10%GonadotrophicadenomasSecrete luteinizing hormone (LH), follicle stimulating hormone (FSH) and their subunitsBasophilicUsually doesn't cause symptoms10%Thyrotrophic adenomas (rare)Secrete thyroid-stimulating hormone (TSH)Basophilic to chromophobicOccasionally hyperthyroidism, usually doesn't cause symptomsLess than 1%Null cell adenomasDo not secrete hormonesMay stain positive for synaptophvsin 25% of pituitary' adenomas are nonsecretive