Successful treatment with enfortumab-vedotin of metastatic signet ring cell cancer expressing nectin-4 and originating from the bladder

Introduction

As an aggressive adenocarcinoma phenotype, primary signet ring cell carcinoma of the urinary bladder is an extremely rare variant. The prognosis of metastatic signet ring cell carcinoma of the urinary bladder is extremely poor and the clinical course for its specific pathogenesis remains unelucidated.

Case presentation

A 64-year-old Japanese male patient was diagnosed with invasive urothelial carcinoma with glandular differentiation of a signet ring cell-type with pT4aN0M0, and he was eventually diagnosed with metastatic signet ring cell carcinoma of the urinary bladder. He was initially responsive to systemic combination induction chemotherapy of S-1 and cisplatin followed by avelumab switch maintenance therapy; however, signet ring cell carcinoma of the urinary bladder relapse occurred in the pathological findings of a biopsy from the right thigh. Immunohistochemical analysis of this specimen identified strong positive staining for nectin-4 and, following enfortumab-vedotin treatment, the patient showed a good response.

Conclusion

We thus describe a rare case of metastatic signet ring cell carcinoma of the urinary bladder with nectin-4 expression diagnosed by a biopsy of a metastatic site.

Breast metastasis from signet ring cell carcinoma of the urinary bladder: A case report

Carcinoma of the bladder metastatic to the breast is only sporadically reported in the literature. To the best of our knowledge, the present report is the first described case of signet ring cell carcinoma of the urinary bladder metastasizing to the breast. The patient was a 43-year-old woman who underwent transurethral partial cystectomy for signet ring cell carcinoma of the urinary bladder and adjuvant chemotherapy with cisplatin and gemcitabine. At 7 months postcystectomy, the patient presented with a solitary nodule in the right breast. Following transdermic core needle puncture biopsy of the lesion and histological examination, the tumor was found to be composed of signet ring cells, which were similar to the cells in the original cystectomy specimen. The patient underwent mastectomy without further chemotherapy and has remained free from metastasis to other organs during 1 year follow-up.