This is an unusual case of invasive lobular carcinoma of the breast presenting as an orbital metastasis. A 70 year-old female presented with a gradually worsening blurred vision, periorbital swelling and ascites. The biopsy of the eyelid demonstrated dense fibrosis with neoplastic cells and the diagnosis of carcinoma was made; however, the site of origin of carcinoma was difficult to determine. The histopathologic characteristics of the carcinoma in the orbit and ascites fluid combined with the immunophenotypic features helped determine the primary site of the malignancy. Subsequently, the primary malignancy was identified by examination of the patient's breast.
2012 by The Japanese Society of Internal Medicine