Ipilimumab cystic hypophysitis mimicking metastatic melanoma

• Main Authors: John Wallace, BS, Martin Krupa, MD, James Brennan, MD, Frank Mihlon, MD
• Format: Article
• Language: English
• Published: Elsevier 2018-06-01
• Series: Radiology Case Reports
• Online Access: http://www.sciencedirect.com/science/article/pii/S1930043317304818

Ipilimumab is an immunotherapeutic agent used in the treatment of metastatic melanoma, and is known to cause hypophysitis in some patients. Magnetic resonance imaging of ipilimumab-induced hypophysitis typically shows diffuse enlargement of the pituitary gland with variable enhancement or enlargement of the infundibulum. This often produces a diagnostic dilemma as melanoma not uncommonly metastasizes to the pituitary gland due to the rich vascular plexus of the hypophyseal portal system, and has a similar imaging appearance to autoimmune hypophysitis. We present a case of a 49-year-old man with a Clark level 4 melanoma of the left calf with inguinal nodal metastases that was treated with resection and 2 cycles of ipilimumab, and subsequently developed a “cystic” pituitary mass. To our knowledge, all of the described cases of ipilimumab-induced hypophysitis to date have shown solid enhancement on imaging. Because metastatic melanoma to the pituitary gland often has internal hemorrhage that produces a “cystic” appearance, and ipilimumab-induced hypophysitis is typically a solidly enhancing abnormality, this presented a significant diagnostic and therapeutic dilemma. Our patient's symptoms, although significant, did not necessitate immediate surgical intervention, and a conservative approach of withholding the ipilimumab and administering therapeutic corticosteroids was pursued. The patient's symptoms abated and follow-up magnetic resonance imaging 1 month later showed near complete resolution of the pituitary abnormalities. As such, this is a unique case of ipilimumab-induced hypophysitis presenting as a “cystic” pituitary mass. Keywords: Hypophysitis, Ipilimumab, Pituitary mass, Pituitary inflammation