Carcinoma with signet ring cell differentiation associated with invasive breast cancer: A case report.

Carcinoma with signet ring cell differentiation is uncommon in patients with invasive breast cancer. Clinical evidence has suggested that the prognosis of this tumor is usually poor if the stage is advanced. The case of a 40-year-old female patient with primary cancer in the right breast accompanied by bilateral neck, axillary, right subclavian and mediastinal lymph node metastases, and left breast metastasis is presented in the current study. The patient developed superior vena cava syndrome and was restricted in lifting the upper right limb when presenting at the Third Affiliated Hospital of Shenzhen University, Shenzhen. The histopathological and immunohistochemical features included ~80% of the tumor cell area having a signet ring cell pattern, exhibiting the phenotype of lobular carcinoma, and ~20% of the tumor cell area exhibiting a ductal carcinoma immunophenotype with neuroendocrine expression The patient received chemotherapy with paclitaxel liposomes and doxorubicin hydrochloride liposomes according to the general guidelines for the treatment of stage IV breast carcinoma. The patient achieved a partial response after 4 cycles of treatment, and then experienced progressive disease in the form of brain metastasis after 6 cycles. Owing to the rarity of carcinoma with signet ring cell differentiation in invasive breast carcinoma, this case report discusses the patient's clinical and histopathological characteristics, and the treatment prognosis.