Pituitary adenoma - lactotroph cell

There is a large tumor expanding the sella and also extending to the suprasellar cistern, characterized by a mixture of solid and cyst components. Hyperattenuation of the solid parts raises the possibility of hemorrhage. Further assessment with MRI has been already organized. 

There is a bilobed sellar and suprasellar cistern mass with a focal waist at the level of the expanded diaphragm sella. The mass measures 39 mm in craniocaudal dimension with the sellar component larger in axial dimensions when compared to the suprasellar component. There is evidence of chronicity with expansion and remodeling of the sella turcica. The mass demonstrates predominantly peripheral thick enhancing solid tissue with a sizable T2 hyperintense non-enhancing cystic component. No areas of focal intrinsic high T1 signal within this mass although the fluid component is moderately high on T1 likely representing proteinaceous material. Less than 180 degrees of contact with the cavernous segment internal carotid arteries bilaterally with the flow voids of the internal carotid arteries preserved. The optic chiasm is displaced both superiorly and posteriorly and is stretched by the mass. The cisternal segments of the optic nerves bilaterally are also expectedly stretched and uplifted by the tumor. The A1 segments and anterior communicating artery are also displaced superiorly by this mass with a hypoplastic left A1 segment noted. Ovoid 14 mm pineal region lesion does not demonstrate definite enhancement. No hydrocephalus. No evidence of acute cerebral infarction. 

MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a moderately hypercellular adenoma. Tumor cells have mildly pleomorphic round and oval nuclei with vesicular chromatin and a variable amount of pale eosinophilic cytoplasm. These are arranged in solid sheets intersected by thin-walled capillaries. No mitotic figures or areas of necrosis are identified. No normal anterior pituitary tissue is included. Immunohistochemistry shows strong cytoplasmic staining for prolactin in tumor cells. No staining for GH, ACTH, LH, FSH, TSH, cytokeratin CAM5.2 or estrogen receptor (ER) is seen in tumor cells. The features are of a lactotroph cell pituitary endocrine tumor. A small Rathke cleft cyst is noted in the CAM5.2 immunostained section. This is completely surrounded by the tumor.

DIAGNOSIS: Pituitary tumor: Lactotroph cell pituitary endocrine tumor; incidental small Rathke cleft cyst.

Slides courtesy of Prof. Michael Gonzales - RMH Pathology Department