High-Molecular-Weight Insulin-Like Growth Factor II Secreting Phyllodes Tumor of the Breast Presenting As a Hypoglycemic Coma: A Case Report

We report the case of a patient who presented with a hypoglycemic attack associated with a Phyllodes tumor and the presence of high-molecular-weight Insulin-like Growth Factor II (IGF-II). A 42-year-old premenopausal woman, who had had a palpable mass in her left breast for several months, was found unconscious at her home by a family member early in the morning. She was emergently transported to our hospital. Her clinical examination revealed an approximately 15-cm mass in the entire left breast. Her blood glucose level was 33 mg/dL, resulting in hypoglycemia, and a 50% glucose injection immediately improved her awareness level. Thoracoabdominal computed tomography demonstrated a large, lobulated left breast tumor showing heterogeneous internal echotexture without enlargement of the lymph nodes (axillary, supraclavicular, cervical, and mediastinum) or distant metastasis. We performed a vacuum-assisted needle biopsy of the breast lesion that showed a Phyllodes tumor. We performed mastectomy, including the tumor, and the patient recovered from the hypoglycemic episode. The histological examination revealed a borderline Phyllodes tumor. Immunohistochemical examinations revealed neoplastic cells diffusely positive for IGF-II. Moreover, Western blot analysis demonstrated large amounts of highmolecular-weight IGF-II in the resected tumor. No relapse of a hypoglycemic attack and tumor recurrence has been reported post-surgery.