Cystic metastasis of prostate cancer: A case report.

Rationale: Prostate cancer often metastasizes (most commonly to the pelvic lymph nodes and axial skeleton); however, metastases to the pelvic cavity as a solitary mass are unusual. While metastatic prostate cancer is unconventional in pelvic cavity, cystic pelvic lesions are even more scarce. Accurate identification of cystic metastasis can be helpful in management of prostate cancer. Patient concerns: A 64-year-old male was admitted to our hospital due to urethral irritation symptom and dysuria. Diagnosis: In addition to prostate cancer, abdominal computed tomography (CT) scanning andmagnetic resonance imaging (MRI) of the prostate revealed that a cystic mass was located at right pelvic cavity. Histopathological examination diagnosed the pelvic cystic mass as metastasis from prostatic cancer. Immunohistochemistry results demonstrated Calretinin (+), D2-40 (-), Ki-67 (10%+), Vimentin (-), CK-pan (+), CK5/6 (-), WT-1 (-), PSA (+), SALL4 (-), Villin (-), CK20 (-), CK7 (-), PAX-8 (-), and TTF-1 (-). Interventions: The cystic mass was removed. Primary cancer of the prostate was reserved as well. After discharge, the patient underwent in a two-year androgen deprivation therapy (ADT) treatment. Outcomes: After 13 months of discharge, no disease progression was found in the patient. Lessons: Although cystic prostate cancer is rare, the occurrence possibility should be considered when cystic lesions are accompanied with prostate cancer.