Adnexal masses are not uncommon in patients with breast cancer. Breast cancer and ovarian malignancies are known to be associated. In patients with breast cancer and co-existing pleural effusions, ascites and adnexal masses, the probability of disseminated disease is high. Nevertheless, benign ovarian masses can mimic this clinical picture when they are associated with Meigs' syndrome making the work-up and management of these patients challenging. To our knowledge, there are no similar reports in the literature and therefore we present this case to highlight this entity.

A 56-year old woman presented with a 4 cm, grade 2, invasive ductal carcinoma of her left breast. Pre-treatment staging investigations showed a 13.5 cm mass in her left ovary, a small amount of ascites and a large right pleural effusion. Serum tumour markers showed a raised CA125 supporting the malignant nature of the ovarian mass. The cytology from the pleural effusion was indeterminate but thoracoscopic biopsy failed to show malignancy. The patient was strongly against mastectomy and she was commenced on neo-adjuvant Letrozole 2.5 mg daily with a view to perform breast conserving surgery. After a good response to the hormone manipulation, the patient had breast conserving surgery, axillary sampling and laparoscopic excision of the ovarian mass which was eventually found to be a benign ovarian fibroma.

Despite the high probability of disseminated malignancy when an ovarian mass associated with ascites if found in a patient with a breast cancer and pleural effusion, clinicians should be aware about rare benign syndromes, like Meigs', which may mimic a similar picture and mislead the diagnosis and management plan.