FRI345 A Rare Case Of Pituitary Histoplasmosis Presenting With Hypopituitarism

Disclosure: A. Jung: None. J. Tan: None. S. Charatz: None. S. Azim: None. A 58-year-old female presented to the endocrine clinic with a history of headache of one year duration. Prior to the visit, she had undergone a right middle lobe lung resection. Histopathology revealed necrotizing granulomas with yeast resembling histoplasmosis on fungal stains. She had no past history to suggest that she was immunocompromised. The patient had completed a three months course of itraconazole. Shortly after, she experienced daily headaches. Pituitary MRI demonstrated an enlarged 1.5cm pituitary gland without compression of the optic chiasm. Laboratory tests showed hypogonadotropic hypogonadism with LH 2.4 mIU/mL (15.9- 54.0), FSH 9.6mIU/mL (23 -116.3), and estradiol 14 pg/mL (<32.2). Free T4 was low 0.7 ng/dL (0.9-1.8) without elevated TSH 1.81 uIU/mL (0.55-4.78). Prolactin was 29.7 ng/mL (2.8-29.2). GH, ACTH, and morning cortisol were normal. Due to the constant headache with hypopituitarism, the decision was made to proceed with transsphenoidal surgery. Pituitary biopsy reported histoplasmosis on Grocott methenamine silver and Periodic acid-Schiff stains. The patient was started on amphotericin B. Repeat MRI confirmed the decrease in size of the pituitary gland after the procedure. Pituitary fungal infections are extremely rare. To our knowledge, this is the first reported case of pituitary histoplasmosis presenting with hypopituitarism. Clinicians should be mindful of the rare etiologies of hypopituitarism when evaluating patients with pituitary enlargement and hypopituitarism. Presentation: Friday, June 16, 2023