Adenocarcinoma of the Breast Presenting as Occult Breast Cancer With Axillary and Supraclavicular Lymph Node Metastasis: A Case Report

Breast cancer is a leading cause of cancer-related mortality in women, with over 250,000 new cases diagnosed annually in the United States. Although mortality rates have decreased, breast cancer remains the second most common cause of cancer death in women. Occult breast cancer (OBC), a rare form of breath cancer that typically presents as axillary lymphadenopathy with no evidence of primary disease, accounts for less than 1% of all breath cancer diagnoses. To date, only three cases of OBC treated with radical mastectomy have been documented in the literature. This case presents a 76-year-old female with a benign left breast mass who was subsequently diagnosed with metastatic estrogen receptor/progesterone receptor (ER/PR)-positive ductal cell breast carcinoma after a visible axillary lymph node was detected on follow-up imaging. Due to the rarity of OBC, standardized treatment guidelines have not been established. Our patient underwent a left radical mastectomy with axillary and cervical lymph node dissection. Clinicians should maintain a high index of suspicion for biopsying axillary lymph nodes in females without evidence of breast malignancy, even though OBC has a low incidence rate. This case report aims to present a documented case of OBC and comprehensibly review the existing literature, discussing the available diagnostic and treatment approaches for this condition. We describe the case of a 76-year-old woman referred to surgery consultation due to a mammographic finding of a left superior lateral mass. The mass was biopsied and found to have no malignancy. On follow-up imaging, she was found to have a left axillary lymph node visible. Her only complaints at this time were breast tenderness and swelling. She underwent fine needle aspiration of the mass, which showed atypical cells that led to an excisional biopsy of the detected axillary node. The biopsy pathology report showed ER/PR-positive ductal cell breast carcinoma. The patient underwent left modified radical mastectomy with left axillary and cervical lymph node dissection. It was during this procedure that the pathology report revealed a 2 cm lesion on the left breast that showed ER/PR-positive infiltrating ductal carcinoma with 32 out of the 37 lymph nodes positive for metastatic disease. This case illustrates the importance of having a low imaging threshold in patients with vague breast symptoms. Surgeons should have a high level of suspicion when metastatic breast cancer is found, even if there is no clinical or radiographic evidence of a primary lesion. This includes conducting lymph node biopsies in patients who present with lymphadenopathy without the initial presence of primary breast cancer. Many studies agree that a modified radical mastectomy with lymph node recession is the treatment of choice for metastatic breast cancer without evidence of primary lesion. However, the efficacy of adjuvant treatments like radiation therapy or chemotherapy should be further studied.