Metastatic Breast Carcinoma Masquerading as Pituitary Macroadenoma: A Case Report

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 164-196-Pituitary
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-182
Inhye E Ahn*1, Ashiq R Zaman1, Angel A Rodriguez1, Leah C Folb2, James E Muntz2 and Richard J Robbins1
1The Methodist Hospital, Houston, TX, 2The Methodist Hospital
Introduction: Clinically evident metastases to the pituitary gland are rare. The most commonly reported sites of origin are breast and lung cancers. Here we report a case of what appeared to be a large pituitary tumor that was found, on pathological exam, to be metastatic breast carcinoma.

Clinical Case: A 46-year-old Hispanic female with history of breast cancer presented with progressive bitemporal hemianopsia. The patient was diagnosed with breast cancer six years earlier, underwent mastectomy, and received both platinum-based chemotherapy and Trastuzumab (HerceptinTM). Nine months prior to presentation, the patient presented with recurrence of breast cancer on the contralateral breast and distant metastasis to the ovary. She underwent hysterectomy and bilateral salphingooophorectomy. Despite aggressive management, the patient again presented with vision loss. Preoperative laboratory and MRI workup suggested a non-functional pituitary macroadenoma. Transsphenoidal resection of the high vascular tumor improved the patient’s vision. However, pathology confirmed adenocarcinoma of breast origin mixed with adenohypophyceal cells. After partial resection, the patient developed signs and symptoms consistent with central diabetes insipidus. Replacement with DDAVP, dexamethasone and levothroxine gradually stabilized the patient’s symptoms. Post-operative FDG-PET revealed abnormally high FDG uptakes in pituitary, thyroid and adrenal glands, suggesting metastatic breast carcinoma with tropism for endocrine organs. She is currently under consideration for chemoradiation.

Clinical Lessons:  Malignant metastasis to pituitary is extremely rare and its presentation can mimic benign pituitary adenoma. As seen in this case, a prior diagnosis of breast cancer with evidence of a non-functional pituitary adenoma in imaging should raise suspicion of metastatic disease. The optimal therapeutic strategy against metastatic pituitary lesion remains to be determined.

Nothing to Disclose: IEA, ARZ, AAR, LCF, JEM, RJR

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