Signet ring cell lobular carcinoma of the breast presenting in a cervicovaginal smear. A case report

The presence of extragenital malignant cells in cervicovaginal smears is a rare and usually late event in a patient with a long history of cancer. This, to the best of our knowledge, is the first case of breast cancer initially diagnosed on a Pap smear.

A 50-year-old woman presented with abdominal distension and weight gain. A Pap smear showed numerous signet ring cells and was diagnosed as signet ring cell adenocarcinoma, most likely metastatic from the breast or stomach. Subsequent evaluation revealed bilateral adnexal masses and inguinal lymphadenopathy, leading to hysterectomy and bilateral salpingo-oophorectomy. The ovaries, corpus and cervix were involved by signet ring cell carcinoma. The metastatic tumor proved to be positive for CK7, CEA, estrogen receptor and progesterone receptors and negative for CK20. Despite the absence of a discrete palpable breast mass, a mammogram was recommended based on these results, and an ensuing breast biopsy showed the presence of an infiltrating lobular carcinoma.

Lobular carcinoma of the breast may present in a cervicovaginal smear. Correct interpretation of signet ring cells as metastatic, most likely from the breast or stomach, is helpful in guiding management.