Submitted by Adriana May, MD, and Scott Kulich, MD, PhD
Clinical History
The patient is a male in his 40s who was newly diagnosed with type 2 diabetes mellitus, hypertension, and obstructive sleep apnea. The patient recently began to experience a variety of issues including but not limited to a noticeable increase tongue, jaw, and shoe size, which prompted a clinical workup. MRI of the central nervous system (Figure 1) revealed a hypointense, slightly bilobed, right pituitary gland mass measuring 11 x 7 x 10 mm that focally extended to the left aspect of the gland. No suprasellar extension was noted. Serum insulin-like growth factor-1 (IGF-1) levels were elevated at 571 ng/ml (normal range: 52-328 ng/ml) with an oral glucose tolerance test was positive, and his serum total testosterone was low (237 ng/dL; normal range: 250-1100 ng/dL). The results from the remainder of his laboratory work up was within normal range. The patient subsequently underwent endoscopic endonasal trans-sphenoid surgery (EETS).
Histological Findings
Histological sections demonstrated sheets of cells demonstrating uniform round nuclei with occasional prominent nucleoli. The cytoplasm of the neoplastic cells demonstrated islands of cells with abundant pale eosinophilic cytoplasm as well as regions displaying more basophilic cytoplasm. (Figure 2A). Mitotic figures were inconspicuous. A reticulin stain showed disruption of the normal acinar architecture (Figure 2B). Immunohistochemical stains demonstrated strong diffuse cytoplasmic staining for both synaptophysin and Cam 5.2 in the neoplastic cells without a substantial number of fibrous bodies appreciated on the Cam5.2 stain (Figure 3), Immunohistochemical stains for nuclear markers demonstrated 2 distinct populations of neoplastic cells, one highlighted by TPIT and the other highlighted by PIT1, a subset of which also stained for estrogen receptor (Figure 4). Immunohistochemical stains for pituitary hormones showed the TPIT-positive population to be positive for ACTH while the PIT1-positive population to be variably positive for growth hormone and prolactin.
