Invasive pituitary adenoma
Invasive pituitary adenomas are benign pituitary tumors that infiltrate the dura mater, cranial bone, or sphenoid sinus. Gross invasion at the time of operation is observed in up to 35 % of pituitary adenomas 1) 2) 3).
Atypical or aggressive pituitary adenomas are tumors that rapidly increase in size and may invade into the suprasellar or parasellar regions. They are characterized by a Ki-67 nuclear labeling index greater than 10 %.
They can be presented as Non-pulsatile exophthalmos.
Infrequently they produce cerebrospinal fluid rhinorrhea.
A 57-year-old man presented with visual deterioration and bitemporal hemianopsia. MRI of the brain demonstrated a sellar mass suspected to be pituitary macroadenoma with a displacement of the stalk and optic nerve impingement. The patient underwent stereotactic endoscopic transsphenoidal resection of the mass. Postoperative MRI demonstrated gross total resection. Pathology revealed a sparsely granulated corticotroph adenoma with malignant transformation. Immunohistochemistry showed a loss of expression of MLH1 and PMS2 in the tumor cells. Proton therapy was recommended given an elevated Ki67 index and p53 positivity. Before radiotherapy, there was no radiographic evidence of residual tumor. Temozolomide therapy was initiated after surveillance MRI showed recurrence at 16 months postoperatively. However, MRI demonstrated marked progression after 3 cycles. Next-generation sequencing using the MSK-IMPACT platform identified somatic mutations in MLH1 Y548lfs*9 and TP53 R337C. Immunotherapy with ipilimumab/nivolumab was initiated, and MRI demonstrated no residual tumor burden 34 months postoperatively.
APA is a tumor with frequent recurrence and a short median expected length of survival. Shah et al. demonstrated the utility of immunotherapy in a single case report of APA, with complete resolution of recurrent APA and improved survival compared with a life expectancy 4).