Occult breast cancer presenting as metastatic carcinoma in a right axillary lymph node of a post-menopausal female: A case report and review of literature

Abstract

Introduction: Occult breast cancer (OBC) is a clinically recognizable metastatic carcinoma from an undetectable primary breast tumor. It is rare and accounts for 0.3–1% of all breast cancers, often presenting with lymph node, bone, or skin metastases. It poses a diagnostic challenge for general surgeons, radiologists, and pathologists. Case Report: We present the case of occult breast cancer in a 62-year-old, post-menopausal, female, Nigerian, presenting with a solitary, painless, right axillary lymph node enlargement without a clinical or radiological evidence of a breast mass; and also review the literature. The diagnosis of metastatic breast carcinoma was made and confirmed on histology and immunohistochemistry analysis of the axillary lymph node. Histological examination of the subsequent right breast mastectomy specimen revealed the presence of infiltrating ductal carcinoma even though no definite mass lesion was seen on gross examination. Conclusion: Occult breast cancer can be a diagnostic challenge and should be excluded in any patient presenting with solitary axillary lymphadenopathy. Immunohistochemistry staining patterns can be a mainstay in resolving the differential diagnoses.