Synchronous pituitary neuroendocrine tumors (PitNETs)/adenomas of triple SF1/PIT1/TPIT cell lineages with multiple hormone expression.

Synchronous multiple pituitary neuroendocrine tumors (PitNETs)/adenomas are rare tumors of the anterior pituitary that are characterized by the expression of more than one pituitary transcription factor. Here, we describe and discuss an unusual case of synchronous multiple PitNETs/adenomas of triple SF1/PIT1/TPIT cell lineages. Clinical case presentation was that of a pituitary macroadenoma in a 69-year-old male patient suffering from visual impairment and high prolactin levels. Radiology featured a large, 3 × 2.5 × 3.5 cm suprasellar mass with a biphasic growth pattern. Transsphenoidal resection showed varying macroscopic appearances between anterior and posterior aspects of the tumor, which was confirmed on histology. Immunohistochemistry demonstrated varying expression of steroidogenic factor 1 (SF1) and T-box transcription factor (TPIT) in the anterior part of the tumor, while the posterior aspect of the tumor showed predominant expression of pituitary transcription factor 1 (PIT1). Immunofluorescence showed no colocalization of the different transcription factors in individual tumor cells. Hormone expression comprised FSH and α-subunit (in the SF1-positive components), prolactin (in the PIT1-positive components), and ACTH (in the TPIT-positive components). 6-months post-operative follow-up under treatment with cabergoline led further tumor mass reduction and significant decrease in prolactin levels. In sum, our case study expands existing data on synchronous PitNETs/adenomas of triple SF1/PIT1/TPIT cell lineages, and underscores the importance of comprehensive clinicopathological data assessment and synoptic interpretation. Further, we address so-far published literature on multilineage PitNETs, and suggest that existing pathophysiological knowledge would argue to interpret the findings in our case as synchronous PitNETs / adenomas of different cell lineages with multiple hormone expression.