19q13 amplification with AKT2 and ERCC2 gains in sarcomatoid carcinoma of the urinary bladder.

Sarcomatoid carcinoma of the bladder is a rare and aggressive biphasic malignant neoplasm, representing approximately 0.1-0.3% of all bladder cancers. It is characterized by the coexistence of malignant epithelial and mesenchymal components. Its poor prognosis and limited systemic treatment options underscore the need for improved molecular characterization. A 75-year-old male with chronic cystitis and squamous metaplasia of the bladder presented with acute urinary obstruction caused by a large bladder mass. Histopathological evaluation revealed a biphasic tumor with rhabdomyosarcomatous and adenocarcinomatous components. Following radical cystoprostatectomy (pT2a pN0 cM0), whole-exome sequencing (WES) using the EXaCT-1 pipeline identified amplification of the 19q13 locus, including copy-number gains in AKT2 and ERCC2. Nine months postoperatively, the patient developed metastatic recurrence. This case contributes to the molecular characterization of bladder sarcomatoid carcinoma through WES. The 19q13 amplification with AKT2 and ERCC2 copy-number gains represents a hypothesis-generating finding that warrants further investigation in larger cohorts.