Contributed by Fang-Yi Lee, MD1, 2, Mei-Chin Wen, MD1, 2, John-Wang MD, PhD1, 2
1Departments of Pathology, Taichung Veterans General Hospital
2HungKuang University, Taichung, Taiwan, R.O.C.
A 28-year-old woman presented with amenorrhea and blurred vision for 3 years and was admitted to our hospital for further evaluation. MRI of brain was performed and the coronal T2 weighted image revealed a well defined, high signal mass 26 x 22.5 x 21 mm, in the left anterior lobe of the pituitary gland. The pituitary stalk was elevated with of the hypothalamus (Figure 1). Serum prolactin level was 40.4 ng/ml (normal range: 3.0-20.0 ng/ml). The other results were within normal range. The preoperative survey revealed no evidence of other tumor in the body. The patient underwent transsphenoidal adenomectomy.
Microscopically, the tumor was composed of clusters of large bizarre and pleomorphic tumor cells, which displayed large vesicular nuclei, prominent nucleoli, smudgy chromatin and abundant pale eosinophilic cytoplasm. The tumor cells were arranged in diffuse sheet-like growth pattern. In addition, there were heavy lymphocytes infiltration and germinal centers formation in the background. Mitotic figures were hard to find (Figures 2 and 3). Immunostaining of the tumor demonstrated strong positive staining with synaptophysin (Figure 4), chromogranin (Figure 5) and only a small number of tumor cells reactive for TSH. The other stains for pituitary hormones, including PRL, GH, ACTH, and FSH; and the germ cell related immunostains were all negative. The Ki-67/MIB-1 labeling index was about 10-20%, while the p53 staining was negative. The infiltrative lymphocytes were belonged to the small lymphocyte type and were immunoreactive for CD20 (Figure 6) and CD3 (Figure 7) markers.