Synchronous occurrence of lobular breast carcinoma and granulosa cell tumor of ovary mimicking metastatic lobular breast carcinoma.

Breast cancer is one of the main sources of ovarian metastasis. Diffuse sheet of lobular carcinoma cells can strongly mimic granulosa cell tumor (GCT) which itself is a rare ovarian neoplasm constituting <5% of all the ovarian neoplasms. A 55-year-old female presented with a painful lump in the right breast associated with nipple discharge for 4 months, which on radiological and cytological findings was suspicious of an epithelial malignancy. During routine work-up, a solid-cystic lesion in the left ovarian adnexa was identified. The patient underwent right modified radical mastectomy along with left salpingo-oophorectomy. Histopathological and immunohistochemical features confirmed the diagnosis of a synchronous lobular carcinoma breast with GCT ovary. Simultaneous occurrence of Lobular carcinoma breast (LCB) and GCT ovary is extremely rare. Morphologically, these can look similar, raising a suspicion of LCB metastasis to ovary. This is important to differentiate the two for a proper patient management and prognosis.