Evolution of a refractory prolactin-secreting pituitary adenoma into a pituitary carcinoma: report of a challenging case and literature review.

BACKGROUND: Pituitary carcinomas (PCs), defined as distant metastases of pituitary neoplasms, are very rare malignancies. Because the clinical presentation of PCs is variable, early diagnosis and management remain challenging. PCs are always refractory to comprehensive treatments, and patients with PCs have extremely poor prognoses. CASE PRESENTATION: We describe one case of a prolactin-secreting pituitary adenoma (PA) refractory to conventional therapy that evolved into a PC with intraspinal metastasis. A 34-year-old female was diagnosed with an invasive prolactin-secreting PA in 2009 and was unresponsive to medical treatment with bromocriptine. The tumor was gross totally removed via transsphenoidal surgery (TSS). However, the patient experienced multiple tumor recurrences or regrowth despite comprehensive treatments, including medical therapy, two gamma knife radiosurgeries (GKSs), and four frontal craniotomies. In 2016, she was found to have an intradural extramedullary mass at the level of the fourth lumbar vertebra. The intraspinal lesion was completely resected and was confirmed as a metastatic PC based on histomorphology and immunohistochemical staining. The literature on the diagnosis, molecular pathogenesis, treatment, and prognosis of patients with prolactin-secreting PCs was reviewed. CONCLUSION: PCs are very rare neoplasms with variable clinical features and poor prognosis. Most PCs usually arise from aggressive PAs refractory to conventional therapy. There is no reliable marker to identify aggressive PAs with a risk for progression to PCs; thus, it is difficult to diagnose these PCs early until the presence of metastatic lesions. It is still very challenging to manage patients with PCs due to a lack of standardized protocols for diagnosis and treatment. Establishing molecular biomarkers and the pathobiology of PCs could help in the early identification of aggressive PAs most likely to evolve into PCs.