Abstract
Disclosure: S. Ahn: None. Y. Kim: None. Y. Cho: None. D. Seo: None. S. Kim: None. J. Cho: None. S. Choi: None. K. Kim: None. E. Kim: None. S. Hong: None. Introduction: Histiocytic sarcoma is a rare and aggressive hematopoietic neoplasm derived from non-Langerhans histiocytic cells of the monocyte/macrophage system. Here, we reported the first case of primary histiocytic sarcoma involving pituitary gland. Methods: Medical records were reviewed. Results: A 53 years old Korean men presented with general weakness, polydipsia, polyuria, and abnormal thyroid function test suspicious for secondary hypothyroidism. Laboratory examinations showed growth hormone deficiency, hypogonadotropic hypogonadism, and central diabetes insipidus. The magnetic resonance imaging showed a well-enhanced mass involving entire posterior pituitary gland with stalk thickening. The biopsy of pituitary mass was identified as a malignant tumor consistent with histiocytic sarcoma. This malignant tumor inoperably increased within a short duration and hormone deficiency such as secondary hypothyroidism and adrenal insufficiency additionally developed. Therefore, the patient started radiation therapy with desmopressin, levothyroxine, and hydrocortisone replacement. Conclusion: The biopsy is not regarded as the mandatory procedure for diagnosing patients with central diabetes insipidus with posterior pituitary lesion since in many cases, this is the result of hypophysitis. However, since there is still the possibility of primary malignancy and metastasis involving pituitary gland, an appropriate decision for performing biopsy should be made according to the patient’s clinical situations. Presentation: Thursday, June 15, 2023