8403 A Rare Presentation: Mucosal Melanoma with Pituitary Gland Involvement

Abstract Disclosure: L.R. Sepulveda-Garcia: None. L. El Musa Penna: None. W. Medina-Torres: None. J. Segarra-Villafane: None. Z. Maisonet-Feliciano: None. I. Arroyo-Gomez: None. L.A. Gonzalez-Rodriguez: None. M. Alvarado-Santiago: None. M. Ramirez-Vick: None. Introduction: Sinonasal mucosal melanoma (SNMM) is a rare form of aggressive melanoma with poor prognosis, compromising less than 1% of all melanoma. The most frequently reported symptoms include nasal obstruction and epistaxis, but the manifestation of symptoms may occur late and be nonspecific, causing delays in diagnosis and resulting in a less favorable prognosis. Here we report a rare case of mucosal melanoma with pituitary gland involvement initially thought to be a pituitary adenoma. Clinical Case Description: A 22-year-old male with no previous medical history was found with a biopsy proven pigmented epithelioid melanocytoma (PEM) in the palate. Three weeks after the biopsy, the patient presented with a severe headache, prompting the performance of a CT scan that revealed a pituitary macroadenoma. Several days later he developed acute right eye ptosis requiring emergency evaluation. The patient reported mild epistaxis, headaches, and nausea of 2 weeks duration associated with lack of erections and diminished libido. Physical exam was remarkable for sinus bradycardia, right eye ptosis, and a palate bluish pigmentation. Hormonal work up revealed a prolactin of 23 ng/mL (3.46-19.40), TSH of 2.22 uIU/mL (0.27-4.20), fT4 of 0.37 ng/dL (0.93-1.70), total testosterone <0.007 ng/mL (1.88-6.84), free testosterone of 0.001 ng/mL (0.032-0.168), FSH of 0.41 mIU/mL (2.6-11.0), and LH of 0.27 mIU/mL (0.4-7). Serum cortisol and ACTH levels were found to be low at <1.00 µg/dL (3.7-19.40) and 5.98 pg/mL (0.00-46.00), respectively, but these were taken while patient was given dexamethasone by neurosurgery for headaches. Brain MRI was remarkable for 3.4 cm x 3.3 cm x 3.5 cm sellar mass extending inferior into the sphenoid sinus, posteriorly into the right ethmoid air cells, superiorly into the suprasellar cistern with upward displacement of the optic chiasm, as well as bilateral cavernous sinus invasion. Case outcomes: A diagnosis of hypopituitarism was made. Physiologic doses of hydrocortisone were started after being found with central adrenal insufficiency. This replacement unmasked an arginine vasopressin deficiency also requiring desmopressin therapy. Central hypothyroidism was treated with levothyroxine and treatment for the hypogonadotropic hypogonadism was deferred in the meantime. Biopsy of right sphenoid sinus revealed a mucosal melanoma. Revised pathology slides led to the conclusion that palate PEM was an independent entity to the mucosal melanoma Case discussion: Prognosis is poor in patients with SNMM since this tumor is usually diagnosed at advanced stages. In this case, the sellar mass was initially thought to be a pituitary adenoma that later was found to be an extension of a mucosal melanoma. This case serves as a reminder of the critical role that differential diagnosis plays in evaluating sellar masses. Presentation: 6/1/2024