An occult urothelial carcinoma with wide multiorgan metastases and its genetic alteration profiling: Case report and literature review.

Rationale: Urothelial carcinoma, also named transitional cell carcinoma, is the most frequent occurring malignancy in the urinary system. It mainly invades the surrounding tissues and metastasizes to distant organs in later stages. Patient concerns: Here, we presented an unusual case of occult urothelial carcinoma primarily manifested as a multiorgan metastatic cancer in a 59-year-old man. The patient complained of pain on the left thigh root for a month. The imaging and histopathological examination revealed multiple malignancies in lung, bone, and liver. Diagnoses: The histological evaluation and the immunohistochemistry (IHC) profile of liver, lung, and bone were consistent with the diagnosis of metastases from the original urothelial cancer, while imaging examination was not able to detect a primary lesion in the urinary system. Interventions: Based on the mutation of STK11 M51Ifs* 106 detected by next generation sequencing NGS), we started targeted therapy with everolimus. Outcomes: The patient deteriorated after 3 months of treatment and passed away. Lessons: In this initial report of occult urothelial carcinoma, we obtained information on genetic variations of tumor tissue which could provide important information for subsequent studies on this kind of disease.