Invasive Giant Prolactinoma Presenting as a Nasal Polyp

Abstract

A previously healthy, 14-year-old obese boy (body mass index 33 kg/m2) presented with progressive weight gain, nasal stuffiness, snoring, and a polypoid mass in his left nostril. Imaging studies revealed a homogenously enhancing mass extending from the floor of sella to the nasopharynx, measuring 8.7 × 7.6 cm transversely, 9.9 × 5.4 cm sagittally, and 5.5 × 8.0 cm coronally. The mass occupied the entire nasopharynx and extended bilaterally into inferior orbital fissures and pterygopalatine fossae (Figure). It abutted the basilar artery, temporal lobe parenchyma, and the inferior margin of the sella turcica, and it elevated the anterior pituitary lobe. It also invaded the cavernous sinuses, clivus, and sphenoid bones. The initial prolactin level was markedly elevated at 29 415 ng/mL (normal range 3-18). Biopsy was consistent with pituitary adenoma, with further staining confirming it to be a prolactinoma. His prolactin level was reduced to 12 059 ng/mL while on cabergoline, 0.5 mg/wk for 2 weeks, and subsequently to a present value of 316 ng/mL, on a cabergoline dose of 12 mg/wk. There has also been a significant reduction in the tumor size in 5 years (Figure). Invasive giant prolactinomas present with extrasellar extension and massive serum prolactin elevations.1Symon L. Jakubowski J. Kendall B. Surgical treatment of giant pituitary adenomas.J Neurol Neurosurg Psychiatry. 1979; 42: 973-982Crossref PubMed Scopus (111) Google Scholar Giant prolactinomas (≥4 cm) constitute only 0.5%-4.4% of all pituitary tumors.2Corsello S.M. Ubertini G. Altomare M. Lovicu R.M. Migneco M.G. Rota C.A. et al.Giant prolactinomas in men: efficacy of cabergoline treatment.Clin Endocrinol (Oxf). 2003; 58: 662-670Crossref PubMed Scopus (101) Google Scholar, 3Shrivastava R.K. Arginteanu M.S. King W.A. Post K.D. Giant prolactinomas: clinical management and long-term follow up.J Neurosurg. 2002; 97: 299-306Crossref PubMed Scopus (128) Google Scholar, 4Yu C. Wu Z. Gong J. Combined treatment of invasive giant prolactinomas.Pituitary. 2005; 8: 61-65Crossref PubMed Scopus (35) Google Scholar Clinical and imaging in our case raised the suspicion of nasopharyngeal carcinoma, rhabdomyosarcoma, small round blue cell tumor, and esthesioneuroblastoma. This case highlights the importance of assessing serum prolactin in erosive skull base tumors, as prolactinomas respond to cabergoline obviating the need for extensive surgical resection.