A 55 year-old man complained
dysuria and visited to our hospital. Physical examination showed firm large mass occupying whole abdomen. Computed tomography (CT) demonstrated a huge retroperitoneal
tumor which compressed intestine, liver, kidney, and urinary bladder. We performed extirpation of the
tumor (8.6 kg, largest diameter 60 cm) which was composed of myxoid stromal region associated with cystic pattern. Histological examination revealed that the epithelium of the cystic region was positive for
prostate specific antigen (PSA) immunostaining. The
tumor was diagnosed
phyllodes tumor of the prostate (prostatic stromal proliferation of uncertain
malignancy, PSTUMP). Serum PSA was declined 3.9 ng/ml to 0.9 ng/ml; however, magnetic resonance imaging (MRI) demonstrated a residual (recurrent?)
tumor in the pelvis one month after the operation. We carried out total
prostatectomy and
residual tumor resection.
Phyllodes tumor of the prostate is histologically characterized with biphasic pattern of hyperplastic epithelial
cysts and variably cellular spindle stroma. The
tumor is considered to have malignant potential and several histological factors including cellularity, atypia, etc. are utilized to assess it. However diagnostic criteria and subsequent treatment modalities are not established thus far. Previous reports showed efficacy of total surgical removal rather than partial resection and that we performed radical extirpation of the entire
tumor. Close follow up is needed against this frequently recurrent disease.