Background: Pituitary adenoma represent the third most common primary intracranial tumor in neurosurgical practice constituting about 10% of intracranial neoplasm. In accordance to the new WHO classification pituitary adenoma is classified according to the cell of origin which is detected immunohistochemically. Some of the pituitary adenomas may show features associated with recurrence and resistance to conventional therapy. Serological and IHC correlation helps in separating these high risk adenomas.

AIM: 1. to determine clinical relevance of IHC in pituitary adenomas. 2.Identification of high risk pituitary adenomas based on immunohistochemically

Materials and Methods: 30 surgically resected specimens. Sections were stained for H&E and immunostained for GH, PRL, ACTH, TSH, FSH, LH.

Results: Tumor mainly affected the age group between 24 to 66years. Most cases presented as non functioning macroadenomas. Based on serological and immunohistochemical profile of pituitary adenomas we found the following results: Plurihormonal adenomas-18cases (60%), Silent corticotroph adenoma-5cases (16.67%), Lactotroph adenoma in men-3cases (10%), Null cell adenoma-2cases (6.67%), Functional thyrotroph -1cases, non-functional gonadotroph -1case.

Discussion: The tumors were common between age group of 41-45 yrs, incidence in men were higher. In our study most of the cases were nonfunctional and diagnosed as macroadenomas resulting in pressure effects. The need of the hour is to subtype PA of clinical relevance. With the new WHO classification histological typing , based on immune markers is essential and older classifications of adenomas based on tictorial stains are obsolete. Prognostication based on proliferation markers remains a major challenge in pituitary pathology. Hence high risk category has been identified with the aid of immune markers. 

Conclusion: Earlier the diagnosis of adenoma was considered sufficient for many cases.With new classification based on IHC, it is recommended to correlate the estimated hormones levels with immune markers in routine diagnosis. As this helps in identifying the high risk groups which require intensive investigations and closer follow up.

Keywords: Pituitary Adenoma; Immunohistochemistry; High Risk.