Transformation of Lactotroph Pituitary Adenoma to Metastatic Pituitary Carcinoma: A Case Report.

Aggressive lactotrophic pituitary adenomas rarely transform into metastatic pituitary carcinoma. Moreover, the biological drivers and molecular characteristics that differentiate pituitary adenomas from pituitary carcinomas, or a reliable biomarker for metastatic potential, remain largely unknown. Therefore, long-term monitoring through clinical examinations, laboratory testing, and imaging is crucial for the early detection of such transformations. This approach can lead to aggressive multimodal treatments, including systemic therapies and radiation. Here, we present a rare case involving a 35-year-old male patient who developed an aggressive lactotrophic pituitary adenoma resistant to surgery, radiation, and medical treatments. Five years after undergoing adjuvant radiation therapy to the pituitary gland, the patient's condition progressed, resulting in distant spinal and bony metastases. He completed palliative radiation therapy for these metastases and underwent four cycles of combination immunotherapy for maintenance. Unfortunately, he was later diagnosed with immune checkpoint inhibitor-related hepatitis due to elevated liver enzymes. The case highlights the likely contribution of subtotal resection and high proliferative potential to incomplete remission, as patients without complete remission may have an increased risk of metastatic transformation. Thus, the need for early genetic testing and a prompt multimodal treatment approach is crucial.