Incidentally Detected Ductal Adenocarcinoma Presenting With Isolated Pulmonary Metastasis and a BRCA2 Mutation

Ductal adenocarcinoma of the prostate is a rare and aggressive cancer that often presents with low prostate-specific antigen levels and nonspecific urinary symptoms, leading to a delayed diagnosis. Mutations in DNA repair genes such as BRCA2 may render these cancers susceptible to targeted treatments.

A 78-year-old man developed acute urinary retention despite a prostate-specific antigen of 0.731 ng/mL. Histopathological examination after holmium laser enucleation of the prostate revealed a ductal adenocarcinoma. Imaging revealed multiple lung nodules, and partial lung resection confirmed metastasis. Genomic profiling of the lung metastases revealed a pathogenic BRCA2 mutation. The patient received androgen deprivation therapy, followed by a combination of talazoparib and enzalutamide. Six months later, imaging revealed fewer lung metastases.

This case illustrates the diagnostic challenges of low-prostate-specific antigen ductal adenocarcinoma and demonstrates the potential of molecular profiling to guide personalized treatment with targeted therapies for rare prostate cancer subtypes.