Surface low-grade papillary urothelial carcinoma with an invasive phenotype represents an understudied entity with its clinical behavior, therapeutic responses, and long-term outcomes remaining poorly defined.
We evaluated 17 patients from a single institution with histologically confirmed surface low-grade papillary urothelial carcinoma with an invasive phenotype, followed by longitudinal clinicopathologic analysis to delineate disease trajectories and treatment outcomes.
Surface components of all tumors in this cohort demonstrated a low-grade papillary urothelial carcinoma phenotype. At the initial presentation, 53% of patients had invasive disease, while 47% were diagnosed with noninvasive disease. During follow-up, 37% of those with noninvasive disease appeared to progress to invasive disease within 1 year. At the point when invasive disease was diagnosed, pT1 disease was observed in 77% cases, and pT2-4 was observed in 23%. During subsequent follow-up, 77% of patients experienced recurrences, with 41% requiring therapeutic escalation to intravesical Bacillus Calmette-Guérin or systemic chemotherapy for disease progression. High-grade recurrence was identified in 23% patients. Distant metastases developed in 18% of patients, preferentially involving the lungs and bone. The median survival of the cohort was 66 months, and 1 patient died of disease.
These findings underscore the variable and unpredictable course of this disease phenotype, emphasizing its potential for aggressive evolution despite surface low-grade tumor histology. Vigilant surveillance and early consideration of definitive treatment may be a prudent strategy to mitigate progression risks in this rare subset of patients.
American journal of clinical pathology. 2026 Jun 04 [Epub]
Somnath Mahapatra, Robert M Humble, Fernanda Cordeiro-Rudnisky, Khaled S Hafez, Ulka N Vaishampayan, Arul M Chinnaiyan, Akriti Gupta, Laxmi P Kunju, Aaron M Udager, Simpa S Salami, Todd M Morgan, Samuel D Kaffenberger, Jeffrey S Montgomery, Udit Singhal, Rohit Mehra
Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, MI, United States., Department of Pathology, University of Michigan, Ann Arbor, MI, United States., Department of Pathology, University of Florida College of Medicine, Gainesville, FL, United States., Department of Urology, University of Michigan, Ann Arbor, MI, United States., Rogel Cancer Center, Michigan Medicine, Ann Arbor, MI, United States.