Axillary nodal metastasis of occult breast primary cancer

Occult breast cancer presenting with axillary metastases is an unusual presentation and can be a diagnostic and therapeutic challenge. A comprehensive work-up, including mammogram, sonogram, magnetic resonance imaging, and even pathologic examination of the mastectomy specimen may not disclose the primary tumor in up to one third of patients. We report a case of a 42-year-old female with occult breast cancer presenting axillary nodal metastasis. She complained of a swelling of the right axillary lymph node, but no breast mass was palpable. Biopsy of the lymph node was performed and histological examination showed a metastatic carcinoma. Estrogen receptor of the lymph node was positive. Calcifications were obtained by mammography and ultrasonography of the right axillary node contained metastasis. All these data suggested an occult carcinoma of the breast and modified radical mastectomy was performed. Pathological findings of the removed specimen failed to find the primary breast cancer lesion. Our case is one more example of this rare occurrence. We assume that the primary carcinoma is so small as to escape detection by histology. It is doubtful if mammography can help to localize these elusive lesions. More refined high resolution methods, are needed to solve this oncologic problem.