Metastasis of prostate cancer predominantly takes place in bone and regional lymph nodes. However, metastases to uncommon regions are often regarded as a poor prognostic sign. 1 , 2
Takamori et al. reported a very rare case of prostate cancer recurrence that seemed to be surrounded by seminal vesicle/vas deferens‐like epithelium after radiation therapy. 3
Based on the previous report, congenital cystic anomalies of the seminal vesicle may be classified in to three groups, such as (i) isolated cyst, (ii) cysts associated with upper urinary tract anomalies, and (iii) cysts associated with autosomal dominant polycystic kidney disease. During development, cysts of the seminal vesicle emerge when one is in their 20s and become sexually active. Seminal vesicle cysts are usually below 5 cm, which is often discovered by various symptoms, such as urinary tract infections, infertility, prostatitis, hematuria, and hemospermia. 4 , 5 Cyst of the seminal vesicle is often associated with ipsilateral renal agenesis in around 60% of the patients. The reason seems that the development of the seminal vesicle cyst associated with the defect in the development of the distal mesonephric duct and misdeveloped ureteral budding, which results in the renal agenesis. 4 , 5
Regarding the ectopic prostate, although it is rare, there were several reports in the past. The most common site seems to be the bladder and urethra, followed by seminal vesicle, testis, and epididymis. Some reports also indicated the presence of ectopic prostate in the cervix and vagina in females. 6 The mechanism for the emergence of ectopic prostate has been related to the migration and misplacement of normal tissue, metaplastic change due to chronic inflammation, and retained embryonic tissue.
In the current case, neither renal agenesis nor any symptoms existed.
So, the chance of existence of a seminal vesicle cyst before the emergence of recurrence seems to be low.
Another possibility may be related to the ectopic prostate that developed to be a malignant cancer with the seminal vesicle/vas deferens‐like epithelium.
Due to limited previous evidence, we seem to have no clear answer. However, this case will bring about new insights into the metastatic feature of prostate cancer.
Since metastasis with seminal vesicle‐like epithelium is rare, the long‐term prognosis of this case may be of interest.
Conflict of interest
The author declares no conflict of interest.
References
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