Axillary Hibernoma in woman with Lobular breast cancer and MEN1 syndrome: A case report

INTRODUCTION: The present study reports the case of an axillary hibernoma in a patient with lobular homolateral breast cancer and multiple endocrine neoplasia type1 (MEN-1). Hibernoma is a rare benign adipose tissue tumor, and usually manifests as a slowly growing and painless rubbery mass. These tumors can arise in various sites, but mammary hibernomas remain extraordinarily uncommon. Although hibernomas are metabolically active and therefore “glucose-avid” on fluorodeoxyglucose CT-positron emission tomography (FDG CT-PET), imaging alone is inadequate in providing a reliable diagnosis and definitive differential diagnosis from other malignancy. Only complete surgical excision is diagnostic and, in most cases, curative. PRESENTATION OF CASE: A 42-years-old woman was followed for MEN-1 syndrome associating with hyperparathyroidism, insulinoma, non-secretory adrenal adenoma and thyroid lump. A FDG CT-PET found high glucid hypermetabolism in thickened elongated area on the front axillary line. Hibernoma was diagnosed after realization of prophylactic left mastectomy, homolateral sentinel lymph node biopsy and exeresis of the known axillary lesion. DISCUSSION: Clinical importance lies in distinguishing hibernoma from other benign and malignant breast neoplasms, as well as inflammatory conditions that come into the histologic or radiologic differential. Hibernoma is not currently classified as a non-endocrine tumor related to MEN1, but this association could be not fortuitous for the linkage between modification of Menin protein function and pathogenesis of hibernomas. CONCLUSION: Our case deserves extraordinary attention because, not only it’s a case of MEN1 syndrome associated with hibernoma, but in the context of this lesion there are multiple micro-foci of infiltrating lobular carcinoma.