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Abstract Disclosure: M.V. David-santos: None. M.C. Isidro: None. Background: Metastatic Cancer to the pituitary gland is a rare condition accounting for 0.5% of all pituitary tumors. It rarely manifests clinically and is often found incidentally. Endocrine dysfunction usually arise, with 38.4% of cases presenting with Diabetes Insipidus, while 37.7% as Panhypopituitarism. On the other hand, prevalence of adrenal metastases is at 0.5 to 3.8% with 43% occurring bilaterally. Primary adrenal insufficiency occurs at 12.4% among those with bilateral metastases. Case: A 32-year old Chinese woman was diagnosed with Stage 4 breast adenocarcinoma ER PR Her2 Neu positive with metastases to the axillary lymph nodes, bone and right adrenal in July 2021. She underwent chemotherapy with Paclitaxel and Trastuzumab then radical mastectomy of the left breast in April 2022.5 months post op, PET scan was done which showed a 11 x 18 x 21 mm pituitary mass. In light of the primary malignancy, lesion was considered a metastatic focus. At that time, patient did not exhibit any neurologic symptoms such as blurring of vision or headaches. No polyuria, polydipsia, nocturia, easy fatigability, nausea or vomiting. Physical examination findings were normal. A hormonal panel showed the following: elevated Prolactin at 150 ng/ml (NV 3-20), normal plasma ACTH IRMA 10 pg/ml (NV 50 pg/ml), low 8AM plasma cortisol at 1.55 ug/dL (Ref 5- 25 ug/dL), TSH was low at 0.15iIU/ml (0.27-3.75) while FT4 was normal at 0.87 ng/dl (NV 0.68 - 2.56).ACTH stimulation showed low cortisol at the 30th minute and 1st hour post ACTH infusion. Serum sodium and urine Osmolality were both normal. The hyperprolactinemia was attributed to Stalk effect, while the decreased cortisol was considered as central adrenal insufficiency. She was then started on Prednisone 5mg tab daily. Repeat TSH and FT4 5 months after showed normal TSH at 1.209, low FT4 at 5.97 pmol/L (NV 9.01-19.05). She was started on Levothyroxine 50mcg daily for the central hypothyroidism.Repeat Cranial MRI 4 months post diagnosis of the pituitary mass showed increased in its size. An endoscopic transsphenoidal resection and biopsy of the pituitary mass showed metastatic carcinoma of the pituitary gland. Staining of the sellar tumor were compatible with a metastatic carcinoma of breast origin. Intensity-modulated radiation therapy (IMRT) at 400 gray was done for 5 fractions and Trastuzumab was continued. Cranial MRI done 6 months post IMRT showed decreasing size of the pituitary mass to its latest size of 6 x 9 x 13 mm as of November 2023. Latest Whole abdominal CT scan of the adrenals showed clearing of the right adrenal Nodule. Conclusion: Breast cancer may also metastasize to endocrine organs causing hormonal dysfunction. Although curative treatment is no longer the goal for Metastatic breast cancer, prolongation of the quality of life is an important aspect to consider. Hormonal work up, surveillance and hormonal replacement can help in attaining this goal. Presentation: 6/3/2024
David-Santos et al. (Tue,) studied this question.