Abstract
Background: Some cases of pituitary adenoma must be differentiated from carcinoma. We report a case of giant pituitary adenoma showing marked cellular atypia, which required a careful differential diagnosis from carcinoma.
Case: The patient was a 21-year-old female who was admitted complaining of headache and nausea. CT scan and MRI examinations revealed a large tumor mass measuring 5.7×4.3×4.0cm. The tumor was sharply demarcated, but showed suprasellar extension in the region of the sella turcica, and minimal invasion in the right cavernous sinus. Laboratory examinations revealed an elevated growth hormone level. Imprint cytology of the tumor disclosed that the tumor cells were round to polygonal with light-green or pale stained cytoplasm. Nuclear size was variable and often accompanied by marked atypism and pleomorphism with one or two prominent nucleoli. Multinucleated giant cells and nuclear inclusion bodies were also encountered, but no mitotic cells were found. Neoplastic cells were positive for chromogranin A, cytokeratin, and growth hormone on immunohistochemistry.
Conclusion: Pituitary adenoma often shows considerable cellular atypia. For the differential diagnosis from carcinoma, the presence of mitosis and growth activity of cells, in addition to clinical information, is important.
