Silent pituitary plurihormonal adenoma: clinical relevance of immunohistochemical analysis

Non-functional pituitary adenomas (NFPAs) present low growth rates; however, some are aggressive and invasive. In 2017 the World Health Organization recognized clinically aggressive adenomas as “high-risk pituitary adenomas”. These include the sparsely granulated somatotroph adenoma, the Crooke’s cell adenoma, the silent corticotroph adenoma and the plurihormonal Pit-1-positive adenoma (subtype 3).

25-year-old woman who presented oligomenorrhea, increased weight, decreased visual acuity and chronic headache. Biochemical and imaging evaluation showed a NFPA. Transsphenoidal surgery was performed with complete resection of lesion, and during short-term follow-up it was observed recurrence, which is why the patient needed two more interventions. The immunohistochemistry reported: ACTH ++ 90%, prolactin ++ 20%, GH ++ 5%, CKAE1-AE3 +++ 90%, Ki-67 10%. The final diagnosis was plurihormonal adenoma, since the immunohistochemical analysis was positive for more than one pituitary hormone and suggested two distinct cell lineages: Pit-1 and Tpit, both recognized as aggressive adenomas.

This case report highlights the significance of a comprehensive immunohistochemical study, which includes transcriptional factors to classify cell lineage, in order to predict aggressiveness and provide personalized treatment.